Updated on 2024/07/22

写真a

 
KAWANISHI, Tetsuya
 
Affiliation
Faculty of Science and Engineering, School of Fundamental Science and Engineering
Job title
Professor
Degree
Ph. D. in Engineering ( Kyoto University )

Research Experience

  • 2015.04
    -
     

    Waseda University   Department of Electrical and Fundamental Systems, School of Fundamental Scienece and Engineering, Faculty of Science and Engineering

  • 2003.12
    -
    2004.05

    University of California at San Diego   Electrical and Computer Engineering department   Visiting Scholar

  • 1998.04
    -
     

    Communications Research Laboratory (now National Institute of Information and Communications Technology)

  • 1997.07
    -
    1998.03

    Kyoto University   Venture Business Laboratory

  • 1994.01
    -
    1995.09

    Matsushita Electric Industrial   Production Engineering Laboratory

Education Background

  • 1995.10
    -
    1997.07

    Kyoto University   Graduate School of Engineering   Department of Electronics and Communication  

  • 1992.04
    -
    1994.03

    Kyoto University   Graduate School of Engineering   Department of Electronics  

  • 1988.04
    -
    1992.03

    Kyoto University   Faculty of Engineering   Department of Electronics  

Professional Memberships

  •  
     
     

    The Japan Society of Applied Physics (JSAP)

  •  
     
     

    The Institute of Electronics, Information and Communication Engineers (IEICE)

  •  
     
     

    The Institute of Electrical and Electronics Engineers (IEEE)

Research Areas

  • Electron device and electronic equipment

Research Interests

  • 確率

  • 統計

  • 電磁界

  • 光波

  • Probability

  • Statistics

  • Electromagnetic field

  • Light wave

▼display all

Awards

  • Young Scientist Award URSI-GA99

 

Papers

  • Thin-Film Lithium Niobate Modulator for a Flat Frequency-Response over 110 GHz Bandwidth with Integrated Electro-Optic Frequency-Domain Equalizer.

    Yuya Yamaguchi, Pham Tien Dat, Naokatsu Yamamoto, Kouichi Akahane, Atsushi Kanno, Tetsuya Kawanishi

    OFC     1 - 3  2024

  • 40-Gbit/s Mobile FSO with High-speed Beam Stabilizer and 2D-PDA-based Diversity Receiver for Support Robots.

    Zu-Kai Weng, Yuki Yoshida, Toshimasa Umezawa, Abdelmoula Bekkali, Michikazu Hattori, Atsushi Matsumoto, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi, Kouichi Akahane

    OFC     1 - 3  2024

  • Demonstration of Robust Mobile Free Space Optical System using High-speed Beam Tracking and 2D-PDA-based Spatial-Diversity Reception.

    Zu-Kai Weng, Yuki Yoshida, Toshimasa Umezawa, Abdelmoula Bekkali, Michikazu Hattori, Atsushi Matsumoto, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi, Kouichi Akahane

    OFC     1 - 3  2024

  • Thermal Study for High-Photocurrent Photodetector in Non-Saturation Region Using Thin Substrate, Thin Absorber, and Flip- Chip Bonding Process.

    Yaofeng Yi, Toshimasa Umezawa, Kouichi Akahane, Tetsuya Kawanishi

    IEEE Access   12   56414 - 56421  2024

    DOI

  • High-Responsivity Unitraveling Carrier-Type Photodetector Using Avalanche InAlAs as a Collector at a High-Frequency Range.

    Yaofeng Yi, Toshimasa Umezawa, Kouichi Akahane, Tetsuya Kawanishi

    IEEE Access   12   22813 - 22820  2024

    DOI

  • 5G-NR Radio- and Power-Over-Fiber System Employing Multicore Fiber for Reconfigurable Metasurface Antenna Beam Steering

    A. Bilal, A. Quddious, M. A. Antoniades, A. Kanno, P. T. Dat, K. Inagaki, T. Kawanishi, S. Iezekiel

    Journal of Lightwave Technology    2023.12

    DOI

  • Foreword.

    Tetsuya Kawanishi

    IEICE Transactions on Electronics   106 ( 11 ) 731 - 731  2023.11

    DOI

  • A 262-GHz Wireless IFoF Uplink With Remote Down-Conversion Using Optically Generated Sub-THz LO

    Sungmin Cho, Sang-Rok Moon, Minkyu Sung, Seung-Hyun Cho, Tetsuya Kawanishi, Ho-Jin Song

    IEEE Transactions on Microwave Theory and Techniques    2023.05

    DOI

  • Millimeter Wave Attenuation Due to Wind and Heavy Rain in a Tropical Region.

    Ukrit Mankong, Pakawat Chamsuk, Sitthichok Nakprasert, Sangdaun Potha, Zu-Kai Weng, Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    Sensors   23 ( 5 ) 2532 - 2532  2023.03  [International journal]

     View Summary

    Millimeter wave fixed wireless systems in future backhaul and access network applications can be affected by weather conditions. The losses caused by rain attenuation and antenna misalignment due to wind-induced vibrations have greater impacts on the link budget reduction at E-band frequencies and higher. The current International Telecommunications Union Radiocommunication Sector (ITU-R) recommendation has been widely used to estimate rain attenuation, and the recent Asia Pacific Telecommunity (APT) report provides the model to estimate the wind-induced attenuation. This article provides the first experimental study of the combined rain and wind effects in a tropical location using both models at a frequency in the E band (74.625 GHz) and a short distance of 150 m. In addition to using wind speeds for attenuation estimation, the setup also provides direct antenna inclination angle measurements using the accelerometer data. This solves the limitation of relying on the wind speed since the wind-induced loss is dependent on the inclination direction. The results show that the current ITU-R model can be used to estimate the attenuation of a short fixed wireless link under heavy rain, and the addition of wind attenuation via the APT model can estimate the worst-case link budget during high wind speeds.

    DOI PubMed

  • Delay Compensated Quad-level Delta-sigma Modulation Dual-color DRoF System for Beyond 5G Mobile Fronthaul.

    Zu-Kai Weng, Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi, Kouichi Akahane

    Optical Fiber Communications Conference and Exhibition(OFC)     1 - 3  2023

    DOI

  • Transparent Radio-Fiber-Radio-Fiber System in 100-GHz Band for Indoor Uplink Signal Transmission in Beyond 5G.

    Pham Tien Dat, Yuya Yamaguchi, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi, Kouichi Akahane

    Optical Fiber Communications Conference and Exhibition(OFC)     1 - 3  2023

    DOI

  • Transparent Relay and Switching of THz-wave Signals in 285-GHz Band Using Photonic Technology.

    Pham Tien Dat, Yuya Yamaguchi, Keizo Inagaki, Shingo Takano, Shotaro Hirata, Junichiro Ichikawa, Ryo Shimizu, Isao Morohashi, Yuki Yoshida, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi, Kouichi Akahane

    Optical Fiber Communications Conference and Exhibition(OFC)     1 - 3  2023

    DOI

  • FPGA-driven random walk noise generation for tunable laser linewidth control.

    Yu Zhou, Zu-Kai Weng, Keizo Inagaki, Tetsuya Kawanishi

    IEICE Electronic Express   20 ( 15 ) 20230245 - 20230245  2023

    DOI

  • Experimental Demonstration of Approximate Communication Based on Radio-Over- Fiber Systems.

    Toshiki Ishimaru, Takatomo Mihana, Michihiro Koibuchi, Tetsuya Kawanishi, Makoto Naruse

    IEEE Access   11   65590 - 65598  2023

    DOI

  • Robust Dual-wavelength DRoF Link by Quasi-2-bit 256-QAM OFDM with Delta-sigma Modulation

    Zu-Kai Weng, Pham Tien Dat, Atsushi Kanno, Kouichi Akahane, Tetsuya Kawanishi

    Journal of Lightwave Technology    2023

    DOI

  • Guest Editorial Special Issue on Microwave Photonics

    Paolo Ghelfi, Tetsuya Kawanishi, Chris Roeloffzen

    Journal of Lightwave Technology    2022.10

    DOI

  • 50 GHz High Photocurrent PIN-PD and Its Thermal Effect.

    Yaofeng Yi, Toshimasa Umezawa, Atsushi Kanno, Tetsuya Kawanishi

    2022 27th OptoElectronics and Communications Conference (OECC) and 2022 International Conference on Photonics in Switching and Computing (PSC)(OECC/PSC)     1 - 3  2022

    DOI

  • Coverage Extension of 28 GHz Band Uplink Signals Inside Vehicle Using Analog Radio over Multi-Mode Fiber.

    Hiroki Yasuda, Toshinori Suzuki, Satoshi Tanaka, Takamitsu Aiba, Tomohiro Wakabayashi, Tetsuya Kawanishi

    2022 27th OptoElectronics and Communications Conference (OECC) and 2022 International Conference on Photonics in Switching and Computing (PSC)(OECC/PSC)     1 - 3  2022

    DOI

  • High-Speed Beam Steering LN Optical Phased Array Module using Comb-Electrode.

    Hayato Takemura, Haruto Shinya, Yuya Yamaguchi, Toshimasa Umezawa, Atsushi Kanno, Tetsuya Kawanishi

    2022 27th OptoElectronics and Communications Conference (OECC) and 2022 International Conference on Photonics in Switching and Computing (PSC)(OECC/PSC)     1 - 3  2022

    DOI

  • High-Efficient Pixel Layout Arrangement in High-Speed 2-D Photodetector Array.

    Siyang Duan, Toshimasa Umezawa, Atsushi Kanno, Tetsuya Kawanishi

    2022 27th OptoElectronics and Communications Conference (OECC) and 2022 International Conference on Photonics in Switching and Computing (PSC)(OECC/PSC)     1 - 3  2022

    DOI

  • Modeling and evaluation of millimeter wave scattering from minimally rough surfaces on stones.

    Riku Yoshino, Tomohiko Kanaya, Shintaro Takada, Kunihisa Jitsuno, Keizo Inagaki, Tetsuya Kawanishi

    IEICE Electronic Express   19 ( 13 ) 20220257 - 20220257  2022

    DOI

  • Transparent Fiber-Millimeter-Wave-Fiber System in 100-GHz Band Using Optical Modulator and Photonic Down-Conversion

    Dat, P.T., Yamaguchi, Y., Motoya, M., Oikawa, S., Ichikawa, J., Kanno, A., Yamamoto, N., Kawanishi, T.

    Journal of Lightwave Technology   40 ( 5 ) 1483 - 1493  2022

    DOI

  • High-speed fiber-wireless-fiber system in the 100-GHz band using a photonics-enabled receiver and optical phase modulator

    Dat, P.T., Umezawa, T., Kanno, A., Yamamoto, N., Kawanishi, T.

    Optics Letters   47 ( 5 ) 1149 - 1152  2022  [International journal]

     View Summary

    This Letter describes a high-speed yet simple fiber-wireless-fiber system in the 100-GHz band using a photonics-enabled receiver and optical phase modulator. At the antenna site, a millimeter-wave signal is down-converted to the microwave band using an electronic mixer with a local oscillator signal generated remotely using photonic technology. The down-converted signal is converted to an optical signal using an optical phase modulator. At the receiver, a simple direct detection of the phase-modulated signal is performed using optical filtering technology. To demonstrate the proof-of-concept, we successfully transmitted a 64-quadrature amplitude modulation orthogonal frequency-division multiplexing signal with a record line rate of 80 Gb/s (net data rate of 55 Gb/s) over a system consisting of two radio-over-fiber links and a 5 m wireless link in the 100-GHz band. The proposed system with simple antenna sites and optical transceivers can facilitate the deployment of ultra-dense small cells in high-frequency bands in beyond-5G networks.

    DOI PubMed

  • 800-MHz Bandwidth Signal Transmission with Radio over Multi-Mode-Fiber for Cascaded IFoF-Based C-RAN Mobile Fronthaul

    Hiroki Yasuda, Takamitsu Aiba, Satoshi Tanaka, Toshinori Suzuki, Shota Ishimura, Kazuki Tanaka, Kosuke Nishimura, Hsuan-Yun Kao, Tomohiro Wakabayashi, Tetsuya Kawanishi

    Journal of Lightwave Technology   39 ( 24 ) 7716 - 7725  2021.12

    DOI

  • Radio Over FSO Communication Using High Optical Alignment Robustness 2D-PDA and its Optical Path Switching Performance

    Toshimasa Umezawa, Pham Tien Dat, Kunihisa Jitsuno, Naokatsu Yamamoto, Tetsuya Kawanishi

    Journal of Lightwave Technology   39 ( 16 ) 5270 - 5277  2021.08

    DOI

  • 2-bit Delta-sigma Modulated 32-QAM OFDM based Dual-wavelength Digital RoF Link

    Zu-Kai Weng, Atsushi Kanno, Tetsuya Kawanishi

    2021 Optical Fiber Communications Conference and Exhibition, OFC 2021 - Proceedings     1 - 3  2021.06

     View Summary

    A dual-wavelength digital RoF link was experimentally demonstrated by OSR-reduced 2-bit delta-sigma modulated 32-QAM OFDM. The optically generated data was transmitted over 25-km SMF at receiving power of -9.9 dBm.

  • 1024-QAM analog waveform transmission over a seamless fiber-wireless system in W band

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEEE INFOCOM 2021 - IEEE Conference on Computer Communications Workshops, INFOCOM WKSHPS 2021     1 - 2  2021.05

     View Summary

    We demonstrate a high-fidelity seamless fiber- wireless system in the W band for high-precision analog waveform transmission. The system is realized using a stable radio-over-fiber transmission and a direct receiver in the W band. Satisfactory performance was experimentally confirmed for 512- and 1024-quadrature amplitude modulation orthogonal frequency division multiplexing signals, showing that the seamless system can provide precise analog waveform transmission of radio-wave signals in future mobile networks.

    DOI

  • Terahertz and Photonics Seamless Short‐Distance Links for Future Mobile Networks

    T. Kawanishi, K. Inagaki, A. Kanno, N. Yamamoto, T. Aiba, H. Yasuda, T. Wakabayashi

    Radio Science    2021.02

    DOI

  • Demonstration of 28-GHz Band Radio Signal Transmission into Vehicle by Analog Radio over Multi-Mode Fiber.

    Hiroki Yasuda, Toshinori Suzuki, Hsuan-Yun Kao, Satoshi Tanaka, Shota Ishimura, Kazuki Tanaka, Naokatsu Yamamoto, Atsushi Kanno, Ryo Inohara, Kosuke Nishimura, Takamitsu Aiba, Tomohiro Wakabayashi, Tetsuya Kawanishi

    Optical Fiber Communications Conference and Exhibition(OFC)     1 - 3  2021

  • 240-Gbps SDM-FSO communication using 4-bundle fiber and 2D photodetector array.

    Toshimasa Umezawa, Kunio Jitsuno, Naokatsu Yamamoto, Tetsuya Kawanishi

    Optical Fiber Communications Conference and Exhibition(OFC)     1 - 3  2021

  • Design Considerations of Photonic THz Communications for 6G Networks.

    Minkyu Sung, Sang-Rok Moon, Eon-Sang Kim, Sungmin Cho, Joon Ki Lee, Seung-Hyun Cho, Tetsuya Kawanishi, Ho-Jin Song

    IEEE Wireless Communications   28 ( 5 ) 185 - 191  2021

    DOI

  • Guest Editorial Special Issue on "THz Communications and Networking".

    Ian F. Akyildiz, Tetsuya Kawanishi, Wolfgang H. Gerstacker, Xiaodai Dong, Aydin Babakhani

    IEEE Journal of Selected Areas in Communications   39 ( 6 ) 1499 - 1505  2021

    DOI

  • Transparent Fiber-Radio-Fiber Bridge at 101 GHz using Optical Modulator and Direct Photonic Down-Conversion

    Pham Tien Dat, Yuya Yamaguchi, Keizo Inagaki, Masayuki Motoya, Satoshi Oikawa, Junichiro Ichikawa, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2021 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXPOSITION (OFC)     1 - 3  2021

     View Summary

    We demonstrate the first fiber-radio-fiber system in beyond 90 GHz using low loss optical modulator and direct photonic down-conversion. We successfully transmitted 32-/64-QAM OFDM and single-carrier signal with a record line rate of 71.4 Gb/s and net data rate of 53.7 Gb/s.

  • 3 3 MIMO FiberWireless System in W-Band with WDM/PDM RoF Transmission Capability

    Dat, P.T., Kanno, A., Rottenberg, F., Yamamoto, N., Kawanishi, T.

    Journal of Lightwave Technology   39 ( 24 ) 7794 - 7803  2021

    DOI

  • FSO Receiver with High Optical Alignment Robustness Using High-Speed 2D-PDA and Space Diversity Technique

    Umezawa, T., Yoshida, Y., Kanno, A., Matsumoto, A., Akahane, K., Yamamoto, N., Kawanishi, T.

    Journal of Lightwave Technology   39 ( 4 ) 1040 - 1047  2021

    DOI

  • Seamless Fiber-Wireless System in W-Band Using Optical Phase Modulation and Self-Homodyne Receiver

    Dat, P.T., Umezawa, T., Kanno, A., Yamamoto, N., Kawanishi, T.

    IEEE Photonics Technology Letters   33 ( 20 ) 1159 - 1162  2021

    DOI

  • Millimeter-Wave and Terahertz Fixed Wireless Link Budget Evaluation for Extreme Weather Conditions

    Zu-Kai Weng, Atsushi Kanno, Pham Tien Dat, Keizo Inagaki, Kosuke Tanabe, Eisaku Sasaki, Thomas Kurner, Bo Kum Jung, Tetsuya Kawanishi

    IEEE Access   9   163476 - 163491  2021

    DOI

  • 132 Gb/s 3times 3 Full MIMO Fiber-Wireless Seamless System in W Band Using WDM/PDM RoF Transmission

    Pham Tien Dat, Francois Rottenberg, Atsushi Kanno, Keizo Inagaki, Jerome Louveaux, Naokatsu Yamamoto, Tetsuya Kawanishi

    2020 European Conference on Optical Communications, ECOC 2020     1 - 4  2020.12

     View Summary

    We demonstrate the first 3times 3 full multiple-input multiple-output fiber-wireless seamless system in W band. Satisfactory performance is experimentally confirmed for a total capacity of approximately 119 Gb/s and 132 Gb/s using standard and flexible FBMC/OQAM signals, respectively.

    DOI

  • Electro-optic modulator for compensation of third-order intermodulation distortion using frequency chirp modulation

    Daichi Furubayashi, Yuta Kashiwagi, Takanori Sato, Tadashi Kawai, Akira Enokihara, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEICE Transactions on Electronics   E103C ( 11 ) 653 - 660  2020.11

     View Summary

    A new structure of the electro-optic modulator to compensate the third-order intermodulation distortion (IMD3) is introduced. The modulator includes two Mach-Zehnder modulators (MZMs) operating with frequency chirp and the two modulated outputs are combined with an adequate phase difference. We revealed by theoretical analysis and numerical calculations that the IMD3 components in the receiver output could be selectively suppressed when the two MZMs operate with chirp parameters of opposite signs to each other. Spectral power of the IMD3 components in the proposed modulator was more than 15 dB lower than that in a normal Mach-Zehnder modulator at modulation index between 0.15 and 0.25 rad. The IMD3 compensation properties of the proposed modulator was experimentally confirmed by using a dual parallel Mach-Zehnder modulator (DPMZM) structure. We designed and fabricated the modulator with the single-chip structure and the single-input operation by integrating with 180. hybrid coupler on the modulator substrate. Modulation signals were applied to each modulation electrode by the 180. hybrid coupler to set the chirp parameters of two MZMs of the DPMZM. The properties of the fabricated modulator were measured by using 10 GHz two-tone signals. The performance of the IMD3 compensation agreed with that in the calculation. It was confirmed that the IMD3 compensation could be realized even by the fabricated modulator structure.

    DOI

  • Cascaded IF-Over-Fiber Links With Hybrid Signal Processing for Analog Mobile Fronthaul

    Kazuki Tanaka, Hsuan-Yun Kao, Shota Ishimura, Kosuke Nishimura, Tetsuya Kawanishi, Masatoshi Suzuki

    Journal of Lightwave Technology   38 ( 20 ) 5656 - 5667  2020.10

    DOI

  • Variable-linewidth light source based on Brownian motion random walk in optical phase

    Jun Mochizuki, Keizo Inagaki, Guo-Wei Lu, Takahide Sakamoto, Yuki Yoshida, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEICE ELECTRONICS EXPRESS   17 ( 16 ) 20200216 - 20200216  2020.08

     View Summary

    We proposed a variable linewidth light source using random walk phase noise. As a demonstration, the impact of the laser linewidth on the error-vector magnitude performance in the optical QPSK transmission was evaluated by using the proposed laser source experimentally, where the linewidth tunable range was from 40 kHz to 5 MHz.

    DOI

  • Simple pedestrian detection secondary radar using frequency doubling

    Tetsuya Kawanishi, Satomi Masuda, Erika Shigematsu, Kunihisa Jitsuno, Keizo Inagaki, Atsushi Kanno

    International Conference on Transparent Optical Networks   2020-   1 - 3  2020.07

     View Summary

    This paper describes a simple secondary radar for detection of hidden pedestrians, by using a compact transponder which responds to a radio-wave transmitted from a car. The transponder doubles the frequency of the radio-wave for frequency-domain duplexing with a simple configuration. The distance between the car and the pedestrian can be measured by using a phase detection scheme, with no local oscillators at the pedestrian side.

    DOI

  • On the Sample Complexity of Phase-Retrieval Receiver Based on 2-D Arrayed Photodetectors

    Yuki Yoshida, Toshimasa Umezawa, Atsushi Kanno, Keizo Inagaki, Naokatsu Yamamoto, Tetsuya Kawanishi

    2020 Optical Fiber Communications Conference and Exhibition, OFC 2020 - Proceedings     1 - 3  2020.03

     View Summary

    Sample complexity, or equivalently the required number of photodetectors, of a carrier-less phase-retrieving coherent receiver is investigated numerically based on the experimental data
    it can achieve comparable complexity to conventional coherent receivers.

  • High-Speed Radio-on-Free-Space Optical Mobile Fronthaul System for Ultra-Dense Radio Access Network

    Pham Tien Dat, Atsushi Kanno, Keizo Inagaki, Francois Rottenberg, Jerome Louveaux, Naokatsu Yamamoto, Tetsuya Kawanishi

    2020 Optical Fiber Communications Conference and Exhibition, OFC 2020 - Proceedings     1 - 3  2020.03

     View Summary

    We present a transmission of radio signals in high-frequency band over a seamless fiber-FSO system for ultra-dense radio access network. We successfully transmitted 80-Gb/s and 40-Gb/s 2×2 MIMO FBMC-OQAM signal in the 90-GHz band over the DL and UL direction.

  • High Speed 2D-PDA FSO Receiver for High Optical Alignment Robustness with Space Diversity

    Toshimasa Umezawa, Yuki Yoshida, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2020 Optical Fiber Communications Conference and Exhibition, OFC 2020 - Proceedings     1 - 3  2020.03

     View Summary

    We present a free space optics receiver with high robustness for optical alignment using a large active area, high-speed 2D-PDA, and its demonstration of 40-Gbps (PAM4) signal detection using a space diversity technique in DSP.

  • 30 GHz Radio over FSO System using High Speed 2D-PDA and Its Optical Path Switching Performance.

    Toshimasa Umezawa, Pham Tien Dat, Atsushi Kanno, Kunihisa Jitsuno, Naokatsu Yamamoto, Tetsuya Kawanishi

    European Conference on Optical Communications(ECOC)     1 - 4  2020

    DOI

  • End-to-End Demonstration based on hybrid IFoF and Analogue RoF/RoMMF links for 5G Access/In-Building Network System.

    Hsuan-Yun Kao, Hiroki Yasuda, Shota Ishimura, Kazuki Tanaka, Takamitsu Aiba, Tomohiro Wakabayashi, Kosuke Nishimura, Tetsuya Kawanishi, Ryo Inohara

    European Conference on Optical Communications(ECOC)     1 - 4  2020

    DOI

  • FMCW linear cell radar interference mitigation through control of signal delay in radio-over-fiber links

    Tetsuya Miura, Kazunori Okuda, Atsushi Kanno, Pham Tien Dat, Nobuhiko Shibagaki, Kenichi Kashima, Yosuke Sato, Masato Fujii, Ryoki Haramoto, Kiyomi Uchida, Tetsuya Hayashi, Sevia M. Idrus, Azura Hamzah, Sumiaty Ambran, Farabi Iqbal, Tetsuya Kawanishi

    IEICE Electronics Express   17 ( 15 ) 1 - 5  2020

     View Summary

    To alleviate the danger of foreign object debris on runways, Frequency Modulated Continuous Wave linear cell radar based detection systems have been evaluated in the literature. This radar uses a 90 GHz millimeter wave and radio-over-fiber (RoF) to achieve high detection accuracy and low cost. This paper reports the experimental results of interference mitigation experiments at Kuala Lumpur International Airport. False images formed due to interference can be suppressed by performing simple signal processing on more than one radar image in which the transmission delay in RoF links is discrepant.

    DOI

  • High-Speed Railway Communication System Using Linear-Cell-Based Radio-Over-Fiber Network and Its Field Trial in 90-GHz Bands

    Atsushi Kanno, Naruto Yonemoto, Yosuke Sato, Masato Fujii, Katsuya Yanatori, Nobuhiko Shibagaki, Kenichi Kashima, Pham Tien Dat, Naokatsu Yamamoto, Tetsuya Kawanishi, Nagateru Iwasawa, Nariya Iwaki, Kazuki Nakamura, Kunihiro Kawasaki, Naoki Kanada

    Journal of Lightwave Technology   38 ( 1 ) 112 - 122  2020.01

     View Summary

    A linear-cell-based radio-over-fiber (LC-RoF) system is proposed and demonstrated for efficient mobile communication in high-speed trains without hard handover processes. The configuration of the LC-RoF network and possible router architectures are discussed for the field trial test of the proposed system and for advanced systems in the future. Via the LC-RoF network, 90-GHz, millimeter-wave radio access between the ground and a train car is operated in a centralized manner. The resulting throughput of 1.5 Gbit/s is achieved in the field trial test, which is comprised of 250-Mbaud four-subcarrier differential quadrature phase-shift keying with a forward-error correction code implemented in field-programmable gate arrays to the Shinkansen train traveling at 240 km/h without any interruptions in the connections at the change of radio access units.

    DOI

  • Integrated fiber-wireless system in W band for ultra-dense small-cell and moving-cell network

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2019 IEEE Globecom Workshops, GC Wkshps 2019 - Proceedings     1 - 5  2019.12

     View Summary

    We present a high-speed integrated fiber-wireless system in the W band for transmission of high- frequency radio signals to ultra-dense small cells and moving cells. The system utilizes a wavelength-division-multiplexing intermediate- frequency-over-fiber system and a remote generation and transmission of local oscillator signals. We experimentally confirmed satisfactory performance for the transmission of 4 Ã- 25-Gb/s and 20-Gb/s OFDM signals over a fixed and a switchable system, respectively. The system is highly spectral efficiency and scalable for signal transmission in future mobile networks.

    DOI

  • Evaluation of Bend-Insensitive Plastic and Glass Fiber for 28-GHz RF Transmission

    Takamitsu Aiba, Hiroki Yasuda, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi, Tomohiro Wakabayashi

    OECC/PSC 2019 - 24th OptoElectronics and Communications Conference/International Conference Photonics in Switching and Computing 2019     1 - 3  2019.07

     View Summary

    We have evaluated impact of plastic and glass optical multi-mode fiber to 28 GHz RF transmission. As the results, error vector magnitudes of 16-QAM and 64-QAM modulated signals over fibers are achieved reauired one.

    DOI

  • Radio over Fiber System for Uninterrupted High-Speed Railway Communications

    Atsushi Kanno, Tetsuya Kawanishi

    OECC/PSC 2019 - 24th OptoElectronics and Communications Conference/International Conference Photonics in Switching and Computing 2019     1 - 2  2019.07

     View Summary

    We show the application of radio over fiber networks to high-speed train communication systems. Network control by optical path switching realizes handover-free uninterrupted signal transmission for the car traveling at 240 km/h.

    DOI

  • Dual-Parallel Mach-Zehnder Modulator Integrated with 180-degree Hybrid for Compensation of Third-Order Intermodulation Distortion

    Daichi Furubayashi, Yuta Kashiwagi, Tadashi Kawai, Akira Enokihara, Naokatsu Yamamoto, Tetsuya Kawanishi

    OECC/PSC 2019 - 24th OptoElectronics and Communications Conference/International Conference Photonics in Switching and Computing 2019     1 - 3  2019.07

     View Summary

    We designed and fabricated an electro-optic modulator for optically compensating the nonlinear distortion. The single-chip structure and the single-input operation were realized by integrating a microwave 180-degree hybrid on the DPMZM substrate.

    DOI

  • Full-Duplex Transmission of Nyquist-SCM Signal over a Seamless Bidirectional Fiber-Wireless System in W-Band

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Nguyen Van Dien, Nguyen Tan Hung, Tetsuya Kawanishi

    2019 Optical Fiber Communications Conference and Exhibition, OFC 2019 - Proceedings     1 - 3  2019.04

     View Summary

    We experimentally demonstrate a seamless full-duplex fiber-wireless system in the W-band for Nyquist-SCM signal transmission. Satisfactory performance is confirmed for 45-Gb/s and 20-Gb/s signal transmission over the downlink and uplink directions.

    DOI

  • 1-λ, 16-Parallel Lanes, 50-Gbaud On-Off Keying Multi-Core Fiber Communication Directly Coupled to High Speed 2D-Photodetector Array

    Toshimasa Umezawa, Atsushi Matsumoto, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2019 Optical Fiber Communications Conference and Exhibition, OFC 2019 - Proceedings     1 - 3  2019.04

     View Summary

    We present a newly developed high-speed 16-pixel photodetector array device operated at 50-Gbuad which circumvents the need for fiber splicing, including its receiving performance when coupled to 16-multi-core fibers, assuming next-generation short-range optical fiber communications.

    DOI

  • THz and Photonic Seamless Communications

    Tetsuya Kawanishi

    Journal of Lightwave Technology   37 ( 7 ) 1671 - 1679  2019.04

    DOI

  • Hybrid Optical Wireless-mmWave: Ultra High-Speed Indoor Communications for beyond 5G

    Pham Tien Dat, Atsushi Kanno, Keizo Inagaki, Toshimasa Umezawa, Naokatsu Yamamoto, Tetsuya Kawanishi

    INFOCOM 2019 - IEEE Conference on Computer Communications Workshops, INFOCOM WKSHPS 2019     1003 - 1004  2019.04

     View Summary

    We propose an ultrahigh speed indoor communication network using a novel cross spectrum and cross medium of optical fiber, millimeter-wave (mmWave), and optical wireless communications. As a proof of concept demonstration, 40-Gb/s mmWave signal in the 100-GHz band was successfully transmitted over a seamless fiber-optical wireless system. The proposed system can provide low-latency, spectral and energy-efficient, and cost-effective solution for future beyond 5G or 6G network evolution.

    DOI

  • Seamless convergence of fiber and wireless systems for 5G and beyond networks

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    Journal of Lightwave Technology   37 ( 2 ) 592 - 605  2019.01

     View Summary

    We propose different fronthaul systems for facilitating future mobile networks based on the seamless convergence of fiber-optic and wireless systems in the millimeter-wave (mmWave) bands. First, a flexible and high-performance wireless fronthaul system is proposed through an encapsulation of radio signals onto a converged fiber-mmWave system. A simultaneous transmission of three radio signals over the system is successfully demonstrated. Second, a high-performance optical self-heterodyne system is proposed and demonstrated for the generation and transmission of radio access signals in high-frequency bands. Third, a high-spectral-efficiency optical fronthaul system for the simultaneous transmission of multiple radio signals in different frequency bands is proposed using a subcarrier-multiplexing intermediate-frequency-over-fiber system. Satisfactory performance is experimentally confirmed for the transmission of three different radio signals in the microwave and low- and high-mmWave bands. The proposed systems can overcome the challenges and bottlenecks of the current mobile fronthaul systems and can be useful in different usage scenarios of 5G and beyond networks.

    DOI

  • 25-Gbaud 4-WDM Free-Space Optical Communication Using High-Speed 2-D Photodetector Array

    Umezawa Toshimasa, Sakamoto Takahide, Kanno Atsushi, Matsumoto Atsushi, Akahane Kouichi, Yamamoto Naokatsu, Kawanishi Tetsuya

    JOURNAL OF LIGHTWAVE TECHNOLOGY   37 ( 2 ) 612 - 618  2019.01  [Refereed]

    DOI

  • Design of Optical Receiver for 28 GHz RF Transmission over Multi-mode Fiber.

    Hiroki Yasuda, Takamitsu Aiba, Satoshi Tanaka, Toshinori Suzuki, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi, Tomohiro Wakabayashi

    2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC)(OECC/PSC)     1 - 3  2019

    DOI

  • Characterization of 2D high-speed photodetector array device for SDM fiber communication applications.

    Ken Kusakata, S. Takamizawa, Toshimasa Umezawa, Naokatsu Yamamoto, Tetsuya Kawanishi

    2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC)(OECC/PSC)     1 - 3  2019

    DOI

  • High-Speed Characterization of Parallel Mach-Zehnder Optical Modulators.

    Hugo S. C. Freire, Yuya Yamaguchi, Tetsuya Kawanishi

    2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC)(OECC/PSC)     1 - 3  2019

    DOI

  • Low Loss ultra-compact Mach-Zehnder Modulator on Lithium Niobate Photonic Wire.

    Jiraphat Chunlen, Tuptim Angkaew, Tetsuya Kawanishi

    2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC)(OECC/PSC)     1 - 3  2019

    DOI

  • Reconfigurable Radio-over-Fibre Networks for Interference Mitigation in Linear Cell Radars.

    Tetsuya Kawanishi, Tetsuya Miura, Keizo Inagaki

    21st International Conference on Transparent Optical Networks(ICTON)     1 - 3  2019

    DOI

  • Terahertz and Photonics Seamless Networks.

    Tetsuya Kawanishi

    2019 IEEE Globecom Workshops     1 - 5  2019

    DOI

  • High-Speed and Uninterrupted Communication for High-Speed Trains by Ultrafast WDM Fiber-Wireless Backhaul System

    Pham Tien Dat, Atsushi Kanno, Keizo Inagaki, Francois Rottenberg, Naokatsu Yamamoto, Tetsuya Kawanishi

    Journal of Lightwave Technology   37 ( 1 ) 205 - 217  2019.01

     View Summary

    We developed a high-speed and handover-free communication network for high-speed trains (HSTs) using an ultrafast and switchable wavelength-division multiplexing fiber-wireless backhaul system in the W band. We successfully transmitted approximately 20-Gb/s and 10-Gb/s signals over the switched fiber-wireless links in the downlink and uplink directions, respectively. An ultrafast radio-cell switching of less than 10 μs was experimentally demonstrated in both downlink and uplink directions. Moreover, the possibility of connecting a central station to many remote radio cells was evaluated, confirming that an uninterrupted communication network up to several tens of kilometers can be achieved for HSTs. The proposed system can overcome the current challenges in mobile networks and can provide a potential solution for the provision of advanced services to users on HSTs in future 5G and beyond networks.

    DOI

  • Experimental Evaluation of Wavelength-Dependence of Thin-Film LiNbO3 Modulator with an Extinction-Ratio-Tunable Structure

    Yuya Yamaguchi, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2019 24TH OPTOELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC) AND 2019 INTERNATIONAL CONFERENCE ON PHOTONICS IN SWITCHING AND COMPUTING (PSC)     1 - 3  2019

     View Summary

    We investigate the operation of a thin-film lithium niobite modulator with specific focus on the wavelength dependence. For a precise evaluation of the modulation distortion, we used an extinction-ratio-tunable-type modulator.

    DOI

  • Field Trial of 1.5-Gbps 97-GHz Train Communication System Based on Linear Cell Radio Over Fiber Network for 240-km/h High-Speed Train

    Atsushi Kanno, Pham Tien Dat, Toshimasa Umezawa, Naokatsu Yamamoto, Tetsuya Kawanishi, Nagateru Iwasawa, Nariya Iwaki, Kazuki Nakamura, Kunihiro Kawasaki, Naoki Kanada, Naruto Yonemoto, Yosuke Sato, Masato Fujii, Katsuya Yanatori, Nobuhiko Shibagaki, Kenichi Kashima

    2019 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2019  [Refereed]

  • Simultaneous Compensation of Fiber Nonlinearity and Dispersive Fading Effects by Conjugated-Paired Radio-on-Fiber Transmission with Phase-Shifted Dual-Sideband Downconversion

    Takahide Sakamoto, Guo-Wei Lu, Naokatsu Yamamoto, Tetsuya Kawanishi

    2019 24TH OPTOELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC) AND 2019 INTERNATIONAL CONFERENCE ON PHOTONICS IN SWITCHING AND COMPUTING (PSC)     1 - 3  2019

     View Summary

    We propose and investigate Conjugated-Paired RoF (C-RoF) transmission with phase-shifted down-conversion, which simultaneously compensates for fiber nonlinearity and dispersive fading effects harmful in Radio-on-fiber (RoF) links, without digital signal processing.

    DOI

  • 400-Gbps Space Division Multiplexing Optical Wireless Communication Using Two-Dimensional Photodetector Array

    Toshimasa Umezawa, Takahide Sakamoto, Atsushi Kanno, Shinya Nakajima, Atsushi Matsumoto, Naokatsu Yamamoto, Tetsuya Kawanishi

    European Conference on Optical Communication, ECOC   2018-   1 - 3  2018.11

     View Summary

    We demonstrate 400-Gbps multi-core fiber based optical wireless communication using a newly developed two-dimensional photodetector array (2D-PDA). The 19-parallel beam from 19-core fiber can be successfully coupled with a 19-pixel 2D-PDA in free space.

    DOI

  • Cell-Less Network for Handover-Free Communications to High-Speed Trains Using a Switched WDM Fiber-Wireless Backhaul

    Pham Tien Dat, Atsushi Kanno, Keizo Inagaki, Naokatsu Yamamoto, Tetsuya Kawanishi

    European Conference on Optical Communication, ECOC   2018-   1 - 3  2018.11

     View Summary

    A cell-less network for high-speed and non-interrupted communications to high-speed trains is proposed and demonstrated using a switched WDM fiber-wireless backhaul system. More than 10 Gb/s signal transmission with an ultra-fast cell switching is experimentally demonstrated in the uplink.

    DOI

  • Vector Modulation by Laser and Electroabsorption Modulator With Digital Pre-Coding and Pre-Compensation

    Ukrit Mankong, Praimezt Mekbungwan, Keizo Inagaki, Tetsuya Kawanishi

    Journal of Lightwave Technology     1 - 1  2018.10

    DOI

  • 90-GHz Linear-Cell Systems for Public Transportation Systems

    Tetsuya Kawanishi, Atsushi Kanno, Naokatsu Yamamoto

    International Conference on Transparent Optical Networks   2018-   1 - 4  2018.09

     View Summary

    This paper reviews 90-GHz high-speed wireless links and high-resolution radars based on linear-cell systems consisting of radio-over-fibre for waveform distribution. We focus on applications for public transportation systems including airport runways, railways, etc.

    DOI

  • High Speed 2-D Photodetector Array for Space and Mode-Division Multiplexing Fiber Communications

    Umezawa Toshimasa, Sakamoto Takahide, Kanno Atsushi, Yamamoto Naokatsu, Kawanishi Tetsuya

    JOURNAL OF LIGHTWAVE TECHNOLOGY   36 ( 17 ) 3684 - 3692  2018.09  [Refereed]

    DOI

  • Performance Evaluation of Full-Duplex MIMO Seamless Fiber-Wireless System in W -Band

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEEE Photonics Technology Letters   30 ( 13 ) 1175 - 1178  2018.07  [Refereed]

     View Summary

    We present a full-duplex fiber-wireless system in the $W$ -band for simultaneous transmission of multiple-input multiple-output (MIMO) signals in downlink and uplink directions. The proposed system uses wavelength-division multiplexing in the optical link and parallel-aligned/orthogonally aligned antenna polarizations in the wireless link for the MIMO and full-duplex signal transmission. Satisfactory performance is experimentally confirmed for 2× 2 MIMO OFDM and LTE-A signals in both directions. The system is highly spectral-efficient and scalable for large-scale MIMO signal transmission.

    DOI

  • Wired and Wireless Links to Bridge Networks: Seamlessly Connecting Radio and Optical Technologies for 5G Networks

    Tetsuya Kawanishi, Atsushi Kanno, Hugo S.C. Freire

    IEEE Microwave Magazine   19 ( 3 ) 102 - 111  2018.05  [Refereed]

     View Summary

    As fifth-generation (5G) technology is expected to offer super-broadband mobile services with new features such as low latency for critical applications and low-power operation for Internet of Things (IoT) applications, it will use wireless interfaces for small or spot cells with a new RF resource, the high band (frequencies above 6 GHz), in addition to the low band (below 6 GHz) on macro and small cells coexisting with conventional mobile technologies [1]-[4]. Another feature of 5G wireless interfaces is more precise control of radio waves in space division through the use of multi-antenna technologies, such as massive multiple-input/multiple-output (MIMO) or beamforming [5].

    DOI

  • Spatial Coherent Matched Detection Using High-Speed Two Dimensional Photo-Diode Array for Full-Channel Demultiplexing and Demodulation of Mode-Division-Multiplexed Signals

    Takahide Sakamoto, Toshimasa Umezawa, Guo-Wei Lu, Koichi Akahane, Atsushi Matsumoto, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    European Conference on Optical Communication, ECOC   2017-   1 - 3  2018.04  [Refereed]

     View Summary

    We propose and demonstrate spatial coherent matched detection using two-dimensional high-speed photodiode array. Capturing amplitude and phase distribution, all tributaries of 3×20-Gb/s MDM-QPSK are simultaneously demultiplexed and coherently demodulated without using optical modal fan-out devices.

    DOI

  • Dense SDM 32-Pixel 2-D Photodetector Array

    Toshimasa Umezawa, Tadashige Sakamoto, Atsushi Kanno, Ken Kusakata, Kouichi Akahane, Atsushi Matsumoto, Naokatsu Yamamoto, Tetsuya Kawanishi

    European Conference on Optical Communication, ECOC   2017-   1 - 3  2018.04  [Refereed]

     View Summary

    We present a newly developed 32-pixel, high-speed 2D photodetector array operated at 25 Gbps (NRZ) with SMF and MCF, targeting direct coupling to MCF and FMF in dense SDM communications.

    DOI

  • Linearized LiNbO3 Modulator with Dual Mach-Zehnder Interferometer and Branched Asymmetric CPW Electrode

    Yuya Yamaguchi, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi, Hirochika Nakajima

    European Conference on Optical Communication, ECOC   2017-   1 - 3  2018.04  [Refereed]

     View Summary

    We propose a transfer-function-transformed optical modulator by introducing a branched asymmetric coplanar waveguide electrode. The structure has the potential to achieve low half-wave voltage and large bandwidth while maintaining its flexibility. We confirmed a linearity improvement with the fabricated modulator.

    DOI

  • Millimeter-Wave Integrated Photoreceivers for High Data Rate Photonic Wireless Communication

    Toshimasa Umezawa, Kunihisa Jitsuno, Pham Tien Dat, Kenichi Kashima, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEEE Journal of Selected Topics in Quantum Electronics   24 ( 2 )  2018.03

     View Summary

    We report on the use of 30 and 100 GHz integrated millimeter-wave photoreceivers in high data rate photonic wireless communication. The role of the bandwidth of a narrow-band photoreceiver in increasing the data rate of wireless single carrier transmission is discussed. An 11-GHz bandwidth photoreceiver achieved a data rate of 44.6 Gb/s using an 8 GBd, 64-QAM (quadrature amplitude modulation) signal. A wider bandwidth (19 GHz) integrated photoreceiver was designed and fabricated for use in the 100-GHz range. High-frequency response photoreceivers have the following advantages: they operate in a wide bandwidth easily, use frequency resources efficiently, and are subject to low amounts of atmospheric attenuation. In addition to the single carrier wireless transmission study, a high data rate (12 Gb/s) multicarrier radio over fiber (16-QAM in orthogonal frequency division multiplexing) transmission experiment was demonstrated in order to confirm the ability to increase the data rate with a wide operational bandwidth.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Millimeter-Wave Radio-Over-Fiber Network for Linear Cell Systems

    Atsushi Kanno, Pham Tien Dat, Naokatsu Yamamoto, Tetsuya Kawanishi

    Journal of Lightwave Technology   36 ( 2 ) 533 - 540  2018.01

     View Summary

    We discuss and propose millimeter-wave linear cell systems for signal distribution on railway radiocommunication systems between train and trackside, and a foreign object debris detection system for airport runways using the radio-over-fiber network technology. Linear cell configurations based on wavelength-division multiplexing (WDM) and power-splitter-based distribution networks are discussed and demonstrated experimentally. A single-sideband modulation for data transmission in an intermediate frequency over a fiber system is successfully transmitted with an ultrafast wavelength-tunable laser diode for WDM routing to track the train car within 3 μs. Radar signal distribution by an optical double-sideband suppressed-carrier modulation mitigates the dispersion effect of the fiber cable to transmit a 32-GHz signal into the remote radar heads.

    DOI

    Scopus

    43
    Citation
    (Scopus)
  • THz Communications Enabled by Photonics.

    Tetsuya Kawanishi

    European Conference on Optical Communication(ECOC)     1 - 3  2018

    DOI

  • Optical Modulator with the Digitized Transfer Function for Multilevel Amplitude Shift Keying

    Yuya Yamaguchi, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2018 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)     1 - 3  2018

     View Summary

    We propose and devise a digitized optical modulator for 4-ASK. The proposed device enables optical modulation and waveform shaping for multilevel amplitude shift keying simultaneously. The measured transfer function of the fabricated modulator shows good agreement with the designed function.

    DOI

  • High-speed two-dimensional photodetector array for 4- WDM 25-Gbaud FSO communication

    Toshimasa Umezawa, Takahide Sakamoto, Atsushi Kanno, Kouich Akahane, Atsushi Matsumoto, Naokatsu Yamamoto, Tetsuya Kawanishi

    Optics InfoBase Conference Papers   2018   1 - 3  2018  [Refereed]

     View Summary

    We present a newly developed 32-pixel high-speed 2D photodetector array operated at up to 39 Gbaud, and its application for WDM FSO communicat ions. 4-WDM 25-Gbaud FSO parallel beams could be directly detected by the 2D-PDA.

    DOI

  • Full-Duplex and scalable MIMO fiber-wireless seamless system in W-Band for future mobile networks

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    Optics InfoBase Conference Papers   2018   1 - 3  2018  [Refereed]

     View Summary

    We present a scalable fiber-wireless system in W-band for the simultaneous transmission of MIMO signals in both downlink and uplink directions. Satisfactory performance is confirmed for 2 × 2 MIMO OFDM and LTE-A signals in both directions.

    DOI

  • Radio-over-fiber-based seamless fiber-wireless convergence for small cell and linear cell networks

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    Optics InfoBase Conference Papers   2018   1 - 3  2018  [Refereed]

     View Summary

    We present radio-over-fiber technologies for fiber and wireless convergence for small cell and linear cell networks, including a flexible and low-latency mobile fronthaul for ultra-dense small cells, and high-speed wireless backhaul system for high-speed trains.

    DOI

  • High-speed and handover-free communications for high-speed trains using switched WDM fiber-wireless system

    Pham Tien Dat, Atsushi Kanno, Keizo Inagaki, Toshimasa Umezawa, François Rottenberg, Je´rome Louveaux, Naokatsu Yamamoto, Tetsuya Kawanishi

    Optics InfoBase Conference Papers   2018   1 - 3  2018  [Refereed]

     View Summary

    A high-speed, handover-free communication for high-speed trains by a switched WDM fiber-wireless system in the W-band is presented. More than 20 Gb/s signal transmission with a cell switching time of less than 4 μs is experimentally demonstrated.

    DOI

  • Precise Optical Modulation Using Extinction-Ratio and Chirp Tunable Single-Drive Mach-Zehnder Modulator

    Yuya Yamaguchi, Atsushi Kanno, Tetsuya Kawanishi, Masayuki Izutsu, Hirochika Nakajima

    JOURNAL OF LIGHTWAVE TECHNOLOGY   35 ( 21 ) 4781 - 4788  2017.11  [Refereed]

     View Summary

    We analyzed the complex transfer function and modulation spectrum of the Mach-Zehnder (MZ) modulator with optical power and phase change imbalances. From the calculations, we found that the characteristic operation can be obtained in three cases: high extinction ratio, zero-chirp, and straight-line trajectory in the IQ plane. However, the results also indicate that we cannot achieve an operation equivalent to that of the ideal modulator, due to the small parasitic chirp in a single-drive modulator. To control the extinction ratio and chirp parameter individually, we propose an integrated modulator with some tunable Y-branches. By using the optical-power-imbalance tunable modulators, we experimentally demonstrate the characteristic operations and obtain the modulation spectrum equivalent to the ideal MZ modulator. However, compared to the ideal amplitude modulator, MZ modulators exhibit an intrinsic nonlinearity in the sinusoidal response. Therefore, we used a third-order nonlinearity compensation method using the superposition of electrical third-order harmonics. The measured spectrum consisted of only first-order modulation sidebands, which is equivalent to the ideal double-sideband suppressed-carrier modulation.

    DOI

    Scopus

    16
    Citation
    (Scopus)
  • 80-GHz signal detection in high speed UTC-PD using EO sampling THz probe

    Toshimasa Umezawa, Isao Morohashi, Yoh Ogawa, Kouichi Akahane, Atsushi Matsumoto, Atsushi Kanno, Norohiko Sekine, Naokatsu Yamamoto, Iwao Hosako, Tetsuya Kawanishi

    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz    2017.10

     View Summary

    The W-band signal near the antenna surface is detected using a THz probing system, by assuming near/far electric field distribution measurement on a phased array antenna coupled to an RoF radar system. By using 10 GHz + 12.5 kHz optical sampling pulse with a ZnTe EO probing head, the 80-GHz signal generated by a UTC-PD could be successfully detected as a down-converted signal of 100 kHz. It suggests a potential to measure the electric field distributions of 1-D/2-D patch antenna arrays, used in advanced RoF systems.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Mode separation control of few-mode quantum dot lasers by using a multistep etalon filter

    Kouichi Akahane, Masaki Inui, Ryuji Sakamoto, Shingo Nakane, Masaru Iwao, Toshimasa Umezawa, Atsushi Matsumoto, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi, Hideyuki Sotobayashi

    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz    2017.10

     View Summary

    Semiconductor quantum dots can be used for an optical gain-chip in an external cavity to construct a stable two- or few-mode laser. In this study, we demonstrate wide-range mode separation control of a few-mode laser by using a multistep etalon filter. Since the precise control of multistep thickness in one etalon plate was achieved, the frequency separation of the few-mode laser can be changed by choosing the etalon position. We can change the frequency separation from 83 to 104 GHz by using this method.

    DOI

    Scopus

  • 100-GHz integrated photoreceiver using optical-to-radio converter and enhancement mode PHEMT amplifier driven by photonic power supply

    Toshimasa Umezawa, Eiichi Hase, Atsushi Kanno, Atsushi Matsumoto, Kouichi Akahane, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEEE MTT-S International Microwave Symposium Digest     1865 - 1868  2017.10

     View Summary

    We present a 100-GHz integrated photoreceiver using an optical-to-radio converter and an enhancement-mode PHEMT amplifier driven by all optical resources without an external electric power supply. Technology for the simultaneous generation of radio and power was developed using a zero-bias operational uni-travelling carrier (UTC) high-speed photodetector. To improve the optical-to-electrical conversion efficiency, a 110-GHz enhancement-mode InP-PHEMT amplifier was also newly developed, which operates using an internal electric power supply in an optical-to-radio converter. Using a hybrid integration based on all optical resources, a +5.5 dBm RF output at 97 GHz was successfully achieved through the optical-to-radio conversion process. Herein, the two key devices and the integrated photoreceiver are discussed.

    DOI

    Scopus

  • Concept of sensor over fibres and its application to high resolution millimetre-wave radar

    Tetsuya Kawanishi, Atsushi Kanno, Naokatsu Yamamoto

    International Conference on Transparent Optical Networks     1 - 4  2017.09

     View Summary

    This paper describes the concept of sensor over fibres (SoF), consisting of many sensor heads connected by fibre networks. SoF transfer waveforms from the sensor heads and performs joint signal processing to achieve high-resolution and agile imaging, while wireless sensor networks are digital networks to collect measured data at small sensors. SoF can compile information from sensor heads coherently at central signal processing units. We will also show applications of SoF technologies, such as high resolution millimetre-wave radar for airport runway surveillance.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Millimeter- and terahertz-wave radio-over-fiber for 5G and beyond

    Pham Tien Dat, Atsushi Kanno, Toshimasa Umezawa, Naokatsu Yamamoto, Tetsuya Kawanishi

    Summer Topicals Meeting Series, SUM 2017     165 - 166  2017.08

     View Summary

    This paper reviews our recent research activities on seamless fiber-wireless systems for future mobile networks, including: radio-on-radio-over-fiber
    signal processing-aided multiple signal transmission
    high-capacity seamless system
    and simultaneous power- and radio-over-fiber.

    DOI

    Scopus

    41
    Citation
    (Scopus)
  • Optical fiber network-connected distributed mm-wave radar system

    Tetsuya Kawanishi, Atsushi Kanno, Naokatsu Yamamoto, Naruto Yonemoto, Nobuhiko Shibagaki, Ken-Ichi Kashima

    Summer Topicals Meeting Series, SUM 2017     197 - 198  2017.08

     View Summary

    This presentation reviews radar systems with many antenna units connected by optical networks, which distribute waveforms of wideband frequency modulated millimeter-wave signals, where the range resolution can be a few centimeters.

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • 100-GHz Fiber-Fed Optical-to-Radio Converter for Radio- and Power-Over-Fiber Transmission

    Toshimasa Umezawa, Kenichi Kashima, Atsushi Kanno, Atsushi Matsumoto, Kouichi Akahane, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS   23 ( 3 )  2017.05  [Refereed]

     View Summary

    We have developed a 100-GHz fiber-fed optical-to-radio converter for radio-and power-over-fiber transmission. A zero-bias operational high-speed photodetector (3-dB bandwidth >100 GHz) could be applied for the optical-to-radio converter, taking significant advantage of no-bias feed 100-GHz operation. We have successfully demonstrated simultaneous radio and power generation from one device through a bias-T circuit. A 100-GHz pseudomorphic high electron mobility transistor amplifier allowed a hybrid integrated photoreceiver to enhance the O/E conversion gain. Using the generated electric power, a gate bias in the 100-GHz amplifier was driven. The performance of each device and the integrated photoreceiver is described. High data rate photonic wireless transmission based on photonic power supply without external electric power supply is demonstrated.

    DOI

    Scopus

    26
    Citation
    (Scopus)
  • 100-GHz Fiber-Fed Optical-to-Radio Converter for Radio- and Power-Over-Fiber Transmission

    Toshimasa Umezawa, Kenichi Kashima, Atsushi Kanno, Atsushi Matsumoto, Kouichi Akahane, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS   23 ( 3 )  2017.05

     View Summary

    We have developed a 100-GHz fiber-fed optical-to-radio converter for radio-and power-over-fiber transmission. A zero-bias operational high-speed photodetector (3-dB bandwidth >100 GHz) could be applied for the optical-to-radio converter, taking significant advantage of no-bias feed 100-GHz operation. We have successfully demonstrated simultaneous radio and power generation from one device through a bias-T circuit. A 100-GHz pseudomorphic high electron mobility transistor amplifier allowed a hybrid integrated photoreceiver to enhance the O/E conversion gain. Using the generated electric power, a gate bias in the 100-GHz amplifier was driven. The performance of each device and the integrated photoreceiver is described. High data rate photonic wireless transmission based on photonic power supply without external electric power supply is demonstrated.

    DOI

    Scopus

    26
    Citation
    (Scopus)
  • Coexistence and transmission of multiple radios over seamless fiber-wireless systems

    Tien Dat, Pham, Kanno, Atsushi, Yamamoto, Naokatsu, Kawanishi, Tetsuya

    Proceedings of SPIE - The International Society for Optical Engineering   10128  2017.01  [Refereed]

     View Summary

    © 2017 COPYRIGHT SPIE.In this paper, we present efficient solutions for simultaneous transmission of multiple radio signals over seamless fiber wireless systems, including radio signals in legacy microwave bands and in high frequency bands. At central stations, radio signals can be mapped onto the same optical transport channel using data mapping algorithms and/or subcarrier multiplexing technique. After the fiber transmission, the received signals can be down-converted, digitized, and de-mapped to recover the originally transmitted signals. We present and compare two different methods, including a radio-over-fiber system and optical up-conversion at remote sites and an intermediate-frequency-over-fiber system and an electrical up-conversion at remote sites. We experimentally confirm the suitability of both the transmission methods, and achieve satisfactory performance for all signals, including LTE-advanced, orthogonal frequency-division multiplexing, and filtered-orthogonal frequency-division multiplexing signals. In particular, the latter method can provide a high optical spectral efficiency and low fiber dispersion effect and is suitable for ultra-dense small cell deployment in future mobile networks.

    DOI

    Scopus

  • High responsivity 100 GHz waveguide UTC photodetector

    T. Umezawa, K. Akahane, A. Matsumoto, A. Kanno, N. Yamamoto, T. Kawanishi

    BROADBAND ACCESS COMMUNICATION TECHNOLOGIES XI   10128  2017  [Refereed]

     View Summary

    We present a double cladding, high-mesa-type waveguide UTC photodetector with an improved the responsivity. In this device structure, an InGaAs thin core layer was sandwiched by p-InP/InGaAsP and n-InP/InGaAsP cladding layers, including a UTC structure, in order to obtain a good optical coupling between the waveguide and the fiber. By comparing the resulting mode field with that obtained with a single cladding layer structure, we confirmed that the vertical mode field was enlarged. Without a spot size converter, the measured responsivity was as high as 0.6 A/W at 1550 nm, which suggests a responsivity three times higher than that of back-illuminated structures, and higher responsivity than that of previous reports. A high frequency performance (f(3dB) = 100 GHz) was also measured. The device structure, including the layer, doping level conditions, and optical fiber coupling results are discussed, and its performance is characterized in detail.

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  • High-conversion-gain 100-GHz photoreceiver integrated with UTC-PD and PHEMT amplifier for 92-GHz carrier, 10.7-Gbps photonic wireless communication

    Umezawa, T, Kashima, K, Kanno, A, Dat, P. T, Akahane, K, Matsumoto, A, Yamamoto, N, Kawanishi, T, Kawanishi, T

    European Microwave Week 2016: "Microwaves Everywhere", EuMW 2016 - Conference Proceedings; 46th European Microwave Conference, EuMC 2016     1397 - 1400  2017.01  [Refereed]

     View Summary

    © 2016 EuMA.We successfully designed and fabricated a high-conversion-gain 100-GHz photoreceiver integrated with a UTC-PD and a PHEMT amplifier for 92-GHz carrier photonic wireless communication. Then, in a demonstration of 92-GHz carrier, OFDM, 16-QAM photonic wireless communication, we confirmed that high data rate of 11.03-Gbps (bit error rate of 1× 10-3) could be achieved at a low optical input power, without post amplifiers for the photoreceiver. The designs and the results are discussed.

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    Scopus

  • Multi-layered stacked patch-antennas on electro-optic material for optical modulation

    Wijayanto, Y. N, Wijayanto, Y. N, Kanno, A, Kawanishi, T, Kawanishi, T, Murata, H, Umezawa, T, Yamamoto, N, Okamura, Y

    European Microwave Week 2016: "Microwaves Everywhere", EuMW 2016 - Conference Proceedings; 46th European Microwave Conference, EuMC 2016     945 - 948  2017.01  [Refereed]

     View Summary

    © 2016 EuMA.Multi-layered stacked patch-antennas on an electro-optic (EO) material are proposed for optical modulation. By using multi-layered structures, larger antenna gain can be obtained to induce stronger millimeter-wave electric fields. The induced millimeter-wave electric field can be used for optical modulation through the Pockels effects of the EO crystal. Since the antenna gain is enhanced by using multi-layered stacked patch-antennas, the modulation index improvement can be obtained.

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  • Wide Frequency Range Optical Synthesizer With High-Frequency Resolution

    Hitoshi Kiuchi, Tetsuya Kawanishi, Atsushi Kanno

    IEEE PHOTONICS TECHNOLOGY LETTERS   29 ( 1 ) 78 - 81  2017.01  [Refereed]

     View Summary

    The generation of high-frequency signals including those in the terahertz region has become indispensable in state-of-the-art communication systems. A synthesizer as a measurement device generates signals of desired frequencies with high-frequency resolution. Electric signals (microwaves or millimeter waves) can be generated by a photomixer performing optical-electrical energy conversion based on the phase difference between two coherent optical signals. Recently, the frequency bandwidth for photomixers has reached the terahertz region and photomixers are now more readily available. The main purpose of this letter is to provide an optical synthesizer with a high-frequency resolution (better than 1 Hz) and with seamless frequency coverage from the microwave to the terahertz-wave regions using one apparatus. The system is designed in such a way that the mean of the resolution frequency includes the frequency instability of the generated signal.

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    7
    Citation
    (Scopus)
  • 100 GHz optical-to-radio converter module and its application in radio and power over fiber transmission through multi-core fiber

    T. Umezawa, P. T. Dat, E. Hase, K. Kashima, A. Kanno, K. Akahane, A. Mstsumoto, N. Yamamoto, T. Kawanishi

    2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2017  [Refereed]

     View Summary

    We developed a 100 GHz optical-to-radio converter module integrated with a 100 GHz amplifier, which was applied in radio (12-Gbps, OFDM, 16-QAM. IF = 92-GHz) and power over fiber transmission through a multi-core fiber.

  • Simultaneous Transmission of Multi-RATs and Mobile Fronthaul in the MMW Bands over an IFoF System

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2017  [Refereed]

     View Summary

    We propose and demonstrate a simultaneous transmission of LTE-A, 25-GHz OFDM/FBMC radio access, and 96-GHz filtered-OFDM mobile fronthaul signals over a simple and low cost intermediate-frequency-over-fiber system. We confirm the successful transmission of all signals.

  • 100 GHz optical-to-radio converter module and its application in radio and power over fiber transmission through multi-core fiber

    T. Umezawa, P. T. Dat, E. Hase, K. Kashima, A. Kanno, K. Akahane, A. Mstsumoto, N. Yamamoto, T. Kawanishi

    2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)   36 ( 2 ) 617 - 623  2017  [Refereed]

     View Summary

    We developed a 100 GHz optical-to-radio converter module integrated with a 100 GHz amplifier, which was applied in radio (12-Gbps, OFDM, 16-QAM. IF = 92-GHz) and power over fiber transmission through a multi-core fiber.

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    42
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  • 90 Gb/s hybrid integrated photoreceiver module with high speed 1.5 μm-band QD-SOA

    Matsumoto, A, Umezawa, T, Akahane, K, Kanno, A, Yamamoto, N, Kawanishi, T

    Conference Digest - IEEE International Semiconductor Laser Conference    2016.12

     View Summary

    © 2016 IEICE-ES.We investigated fundamental characteristics of a hybrid integrated photoreceiver module with a 1.5 μm-band quantum dot semiconductor optical amplifier (QD-SOA) and conventional pin-photodiode (pin-PD) as a first stage. The results indicated the photoreceiver integrated with a QD-SOA and QD-PD has the potential to be operated for signals over 100 Gb/s.

  • High characteristic temperature for ridge-waveguide laser with a highly stacked InAs quantum dot structure

    Akahane, Kouichi, Matsumoto, Atsushi, Umezawa, Toshimasa, Yamamoto, Naokatsu, Kawanishi, Tetsuya

    Conference Digest - IEEE International Semiconductor Laser Conference    2016.12

     View Summary

    © 2016 IEICE-ES.A ridge-waveguide laser with highly stacked InAs quantum dot structure based on strain compensation technique was fabricated. The threshold current of this laser was decreased to approximately 75 mA without coating the facet mirror. A high characteristic temperature of over 100 K was obtained using this laser.

  • Investigation on phase-sensitive fiber nonlinearity cancellation in conjugated-paired radio-on-fiber system

    Sakamoto, Takahide, Lu, Guo Wei, Lu, Guo Wei, Kawanishi, Tetsuya, Kawanishi, Tetsuya

    2016 Conference on Lasers and Electro-Optics, CLEO 2016    2016.12  [Refereed]

     View Summary

    © 2016 OSA.We clarify that fiber nonlinearity cancellation in the conjugated-paired radio-on-fiber system is a phase sensitive process. The best nonlinearity tolerance is achieved if the dual sidebands are constructively superposed during photonic down conversion.

  • Performance of 90GHz electro-optic modulator with patch-antennas in high-power wireless irradiation

    Wijayanto, Yusuf Nur, Wijayanto, Yusuf Nur, Kanno, Atsushi, Kawanishi, Tetsuya, Kawanishi, Tetsuya, Murata, Hiroshi, Yamamoto, Naokatsu, Okamura, Yasuyuki

    2016 Conference on Lasers and Electro-Optics, CLEO 2016    2016.12  [Refereed]

     View Summary

    © 2016 OSA.We report a recent progress for performance of 90GHz electro-optic modulator with patch-antennas in high-power wireless radio irradiation. Optical sidebands to carrier ratio of -40dB can be achieved by wireless radio irradiation power of 33dBm.

  • 100 GHz fiber-fed optical-to-radio converter

    Umezawa, T, Kashima, K, Akahane, K, Kanno, A, Yamamoto, N, Kawanishi, T, Kawanishi, T

    2016 Conference on Lasers and Electro-Optics, CLEO 2016    2016.12  [Refereed]

     View Summary

    © 2016 OSA.We demonstrate 100-GHz optical-to-radio converter without electric power supplies by combination of a newly developed bias-free-operational UTC-PD and an integrated bias-tee for effective regeneration of the supplied power to a 100-GHz amplifier.

  • Polarization dependence of avalanche multiplication factor in 1.5 μm quantum dot waveguide photodetector

    Umezawa, T, Akahane, K, Matsumoto, A, Kanno, A, Yamamoto, N, Kawanishi, T, Kawanishi, T

    2016 Conference on Lasers and Electro-Optics, CLEO 2016    2016.12  [Refereed]

     View Summary

    © 2016 OSA.We fabricated 1.5 μm quantum dot waveguide photodetector, and characterized the electrical and optical properties. It was found that the avalanche photocurrent strongly depends on TE/TM polarization.

  • Demonstration of ultraprecision ductile-mode cutting for lithium niobate microring waveguides

    Ryo Takigawa, Eiji Higurashi, Tetsuya Kawanishi, Tanemasa Asano

    JAPANESE JOURNAL OF APPLIED PHYSICS   55 ( 11 )  2016.11  [Refereed]

     View Summary

    In this paper, the application of the ultraprecision ductile-mode cutting method to the fabrication of microring waveguides in lithium niobate crystal was investigated. Although it was difficult to apply a mechanical cutting method to the fabrication of microring waveguides with smooth sidewalls, it was confirmed that no harmful cutting traces on the machined surface occur with the appropriate movement of the cutting tool. The root-mean-square surface roughness of the resulting sidewall was 6.1 nm, which is sufficiently small to suppress the scattering loss of the circulating light. In addition, the conditions for the ductile-mode cutting of lithium niobate crystal were investigated. (C) 2016 The Japan Society of Applied Physics

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    6
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  • Demonstration of ultraprecision ductile-mode cutting for lithium niobate microring waveguides

    Ryo Takigawa, Eiji Higurashi, Tetsuya Kawanishi, Tanemasa Asano

    JAPANESE JOURNAL OF APPLIED PHYSICS   55 ( 11 )  2016.11

     View Summary

    In this paper, the application of the ultraprecision ductile-mode cutting method to the fabrication of microring waveguides in lithium niobate crystal was investigated. Although it was difficult to apply a mechanical cutting method to the fabrication of microring waveguides with smooth sidewalls, it was confirmed that no harmful cutting traces on the machined surface occur with the appropriate movement of the cutting tool. The root-mean-square surface roughness of the resulting sidewall was 6.1 nm, which is sufficiently small to suppress the scattering loss of the circulating light. In addition, the conditions for the ductile-mode cutting of lithium niobate crystal were investigated. (C) 2016 The Japan Society of Applied Physics

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    6
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  • Change of frequency separation for two-mode quantum dot lasers by using a birefringent etalon filter

    Akahane, Kouichi, Inui, Masaki, Umezawa, Toshimasa, Kanno, Atsushi, Yamamoto, Naokatsu, Kawanishi, Tetsuya, Sotobayashi, Hideyuki

    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz   2016-November  2016.11  [Refereed]

     View Summary

    © 2016 IEEE.We have developed a stable two-mode laser by using a quantum dot optical gain chip in an external cavity. In this study, we demonstrate continuous change of frequency separation of a two-mode laser by using a birefringent etalon filter. Since the polarization of the quantum dot optical gain chip is TE-dominant, the frequency separation of the two-mode laser is controlled by rotating the birefringent etalon filter. We can change the frequency separation from 84 to 93 GHz by using this method.

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  • OFDM millimeter-wave radar experiment combined with radio over fiber technology

    Umezawa, T, Jitsuno, K, Kanno, A, Akahane, K, Yamamoto, N, Kawanishi, T

    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz   2016-November  2016.11  [Refereed]

     View Summary

    © 2016 IEEE.We have demonstrated an orthogonal frequency division multiplexing (OFDM) radar experiment combined with millimeter-wave radio over fiber (RoF). In result, high flame rate and high space resolution of 30 cm in 5 m distance (theoretical space resolution of 1.52 cm) was successfully achieved.

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    2
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  • Seamless Fiber-Wireless Bridge in the Millimeter- and Terahertz-Wave Bands

    Atsushi Kanno, Pham Tien Dat, Norihiko Sekine, Iwao Hosako, Naokatsu Yamamoto, Yuki Yoshida, Ken-Ichi Kitayama, Tetsuya Kawanishi

    JOURNAL OF LIGHTWAVE TECHNOLOGY   34 ( 20 ) 4794 - 4801  2016.10  [Refereed]

     View Summary

    Fiber-wireless transmission in the terahertz-wave band as well as in the millimeter-wave band is the key for a seamless integration of radio and optical networks in a physical layer. Advanced optical fiber communication technology enables a high precision direct waveform transfer between optical and radio domains. For realization of a seamless conversion, an optical-terahertz converter is configured with optical heterodyning for an optical-to-terahertz conversion. Analog optical modulation techniques by an input millimeter-wave signal and an intermediate frequency component after a frequency downconversion are utilized for a terahertz-to-optical conversion. A quadrature phase-shift keying signal transmission in an optical-fiber-to-radio-to-optical-fiber link (fiber-wireless bridge) is successfully demonstrated with the 90 and 300-GHz signals, simultaneously, using an optical frequency comb source. The possible transmission distance in severe weather conditions in these frequency bands is also discussed.

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    27
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  • Seamless Fiber-Wireless Bridge in the Millimeter- and Terahertz-Wave Bands

    Atsushi Kanno, Pham Tien Dat, Norihiko Sekine, Iwao Hosako, Naokatsu Yamamoto, Yuki Yoshida, Ken-Ichi Kitayama, Tetsuya Kawanishi

    JOURNAL OF LIGHTWAVE TECHNOLOGY   34 ( 20 ) 4794 - 4801  2016.10  [Refereed]

     View Summary

    Fiber-wireless transmission in the terahertz-wave band as well as in the millimeter-wave band is the key for a seamless integration of radio and optical networks in a physical layer. Advanced optical fiber communication technology enables a high precision direct waveform transfer between optical and radio domains. For realization of a seamless conversion, an optical-terahertz converter is configured with optical heterodyning for an optical-to-terahertz conversion. Analog optical modulation techniques by an input millimeter-wave signal and an intermediate frequency component after a frequency downconversion are utilized for a terahertz-to-optical conversion. A quadrature phase-shift keying signal transmission in an optical-fiber-to-radio-to-optical-fiber link (fiber-wireless bridge) is successfully demonstrated with the 90 and 300-GHz signals, simultaneously, using an optical frequency comb source. The possible transmission distance in severe weather conditions in these frequency bands is also discussed.

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    27
    Citation
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  • Efficient mobile fronthaul for simultaneous transmission of 4G and future mobile signals

    Dat, Pham Tien, Kanno, Atsushi, Yamamoto, Naokatsu, Kawanishi, Tetsuya, Kawanishi, Tetsuya

    2016 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016    2016.10  [Refereed]

     View Summary

    © 2016 IEICE.We present an efficient mobile fronthaul system for co-transmission of radio signals in the microwave and millimeter-wave bands. We successfully transmit a WLAN and an LTE-A signal at 2.6 GHz and 33.6 GHz, respectively, over the system.

  • 11-Gbps 16-QAM OFDM radio over fiber demonstration using 100 GHz high-efficiency photoreceiver based on photonic power supply

    Umezawa, T, Kashima, K, Kanno, A, Akahane, K, Matsumoto, A, Yamamoto, N, Kawanishi, T, Kawanishi, T

    2016 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016    2016.10  [Refereed]

     View Summary

    © 2016 IEICE.A 100 GHz photoreceiver was designed, fabricated, and integrated with a pHEMT amplifier, based on a photonic power supply. In this paper, a high data rate photonic wireless communication over 11 Gbps is demonstrated.

  • Measurement of vectorial response of IQ modulator using optical interference

    Yamaguchi, Yuya, Seki, Kazuki, Takahashi, Naoki, Kanno, Atsushi, Kawanishi, Tetsuya, Kawanishi, Tetsuya, Izutsu, Masayuki, Izutsu, Masayuki, Nakajima, Hirochika

    2016 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016    2016.10  [Refereed]

     View Summary

    © 2016 IEICE.We propose a new measurement method of modulator response in phasor domain for Mach-Zehnder modulators embedded in IQ modulator using simple equipments. The modulation curve with extinction ratio of 14.7 and 22 dB were measured.

  • Mode-division multiplexing LiNbO<inf>3</inf> modulator using directional coupler

    Kodama, Yutaro, Yamaguchi, Yuya, Kanno, Atsushi, Kawanishi, Tetsuya, Kawanishi, Tetsuya, Izutsu, Masayuki, Izutsu, Masayuki, Nakajima, Hirochika

    2016 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016    2016.10  [Refereed]

     View Summary

    © 2016 IEICE.We designed and fabricated a LiNbO3 integrated optical modulator for mode-division multiplexing, where optical signals in two modes can be independently controlled and combined together. Mode crosstalk was smaller than -20dB in C-band.

  • Electro-optic modulator using millimeter-wave gap-embedded patch antenna with stacked structure

    Aya, Hironori, Wijayanto, Yusuf Nur, Kanno, Atsushi, Kawanishi, Tetsuya, Kawanishi, Tetsuya, Murata, Hiroshi, Okamura, Yasuyuki

    2016 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016    2016.10  [Refereed]

     View Summary

    © 2016 IEICE.We propose new electro-optic modulators using gap-embedded patch antennas with stacked structure. Utilizing stacked structure, the antenna gain, electric field for modulation, and interaction length increase, then modulation efficiency increases 3.65 dB at 60 GHz.

  • 5G TRANSPORT NETWORKS: THE NEED FOR NEW TECHNOLOGIES AND STANDARDS

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEEE COMMUNICATIONS MAGAZINE   54 ( 9 ) 18 - +  2016.09  [Refereed]

     View Summary

    Mobile transport networks will play a vital role in future 5G and beyond networks. In particular, access transport networks connecting radio access with core networks are of critical importance. They will be required to support massive connectivity, super high data rates, and real-time services in a ubiquitous environment. To attain these targets, transport networks should be constructed on the basis of a variety of technologies and methods, depending on application scenarios, geographic areas, and deployment models. In this article, we present several technologies, including analog radio-over-fiber transmission, intermediate-frequency-over-fiber technology, radio-on-radio transmission, and the convergence of fiber and millimeter-wave systems, that can facilitate building such effective transport networks in many use cases. For each technology, we present the system concept, possible application cases, and demonstration results. We also discuss potential standardization and development directions so the proposed technologies can be widely used.

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    36
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  • Transmission of multiband wireless signals over a seamless IM/DD fiber-MMW system

    Nguyen Toan Van, Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Vo Nguyen Quoc Bao, Tetsuya Kawanishi

    IEICE ELECTRONICS EXPRESS   13 ( 15 ) 20160497 - 20160497  2016.08  [Refereed]

     View Summary

    This paper proposes a high-speed multiband filtered-orthogonal frequency division multiplexing (F-OFDM) signal transmission over a seamless fiber-millimeter-wave (MMW) system at 92.5 GHz. The system employs a frequency and phase stabilized optical MMW signal generation at the transmitter and a simple direct detection at the receiver. We confirm a successful transmission of multiband F-OFDM signal over a seamless 20-km single mode fiber (SMF) and 1-m 92.5-GHz wireless system. Compared to the single-band and multiband OFDM signal transmission, the proposed system can provide a much better performance, particularly at the edges of each band.

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    1
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  • Frequency chirp modulation by electro-optic modulator integrated with microwave rat-race circuit and measurement of chirp parameter by using optical fiber dispersion

    Nakamura, Ryota, Yamamoto, Katsuyuki, Kawai, Tadashi, Enokihara, Akira, Yamamoto, Naokatsu, Kawanishi, Tetsuya, Kawanishi, Tetsuya

    IEEE MTT-S International Microwave Symposium Digest   2016-August  2016.08  [Refereed]

     View Summary

    © 2016 IEEE.The rat-race (RR) circuit, which operates as a 180-degree hybrid, with an asymmetric power split ratio was integrated with the dual electrode type electro-optic modulator on the same substrate. Thereby, frequency chirp modulation with a compact configuration was realized. The RR circuit was designed with 4.5 1 power split ratio on a z-cut LiNbO3 substrate. The operation of the modulator was confirmed by observing the output light spectra. Moreover, the chirp parameter was directly measured by using the chromic dispersion of the optical fiber, where the power penalty of detected modulation signals transmitted through optical fiber was observed as a function of the fiber distance. The chirp parameter of the modulated light at 10 GHz was confirmed to be 0.47 by the measurement.

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    3
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    (Scopus)
  • Array of patch-antennas with meandering-gaps on optical modulator for wireless millimeter-wave beam-steering

    Yusuf Nur Wijayanto, Atsushi Kanno, Hiroshi Murata, Tetsuya Kawanishi, Naokatsu Yamamoto, Yasuyuki Okamura

    INTERNATIONAL JOURNAL OF MICROWAVE AND WIRELESS TECHNOLOGIES   8 ( 4-5 ) 759 - 765  2016.06  [Refereed]

     View Summary

    An array of patch-antennas with meandering-gaps on an optical modulator is proposed for wireless millimeter-wave beam-steering through high-speed radio-over-fiber systems. Wireless millimeter-wave can be received by the array of patch-antennas and directly modulated to lightwave by the optical modulator. The wireless millimeter-wave can be steered using the meandering-gaps at the patch-antennas by controlling interaction between millimeter-wave and lightwave electric fields in electro-optic modulation. The basic operation and analysis of the proposed device are discussed. In the experiment, 5 x 5 antenna array in 40 GHz millimeter-wave bands was designed and realized for device characterization and demonstration to wireless millimeter-wave beam-steering. There were five variations of wireless millimeter-wave beam-steering for one-dimensional in xz- or yz-planes that can be obtained with wireless millimeter-wave steerable beams of about +/- 30 degrees. Additionally, 25 variations of wireless beam-steering can be obtained for two dimension in xyz-space through orthogonal optical modulation. The proposed device is promising to be applied in millimeter-wave/tera-hertz bands for future directional wireless communication and sensing with high-speed and high-resolution operation.

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    8
    Citation
    (Scopus)
  • Flexible high-order QAM transmitters for elastic optical networks

    Guo-Wei Lu, Takahide Sakamoto, Tetsuya Kawanishi

    PHOTONIC NETWORK COMMUNICATIONS   31 ( 2 ) 345 - 352  2016.04  [Refereed]

     View Summary

    In order to adapt to the dynamics in the future optical networks, we propose and experimentally demonstrate two flexible high-order quadrature amplitude modulation (QAM) transmitter schemes: (a) a flexible transmitter using a tandem in-phase/quadrature modulators for generating 16QAM, 32QAM, 64QAM signals; and (b) a scheme based on monolithically integrated quad-Mach-Zehnder in-phase/quadrature with binary driving electronics for synthesizing minimum phase-shift keying (MSK), quadrature phase-shift-keying (QPSK), 8-ary phase-shift keying (8PSK), and 16QAM. These schemes provide different approaches to configure a flexible high-order QAM transmitter, either using cascaded off-the-shelf modulators or via highly integrated monolithic modulator. These flexible and reconfigurable transmitter schemes exhibit different characteristics in terms of system performance, which provides the network operators different flexible transmitter solutions suitable for different application scenarios in elastic optical networks.

    DOI

  • Metamaterial antenna integrated to LiNbO3 optical modulator for millimeter-wave-photonic links

    Wijayanto, Y. N, Wijayanto, Y. N, Kanno, A, Fathnan, A. A, Daud, P, Kawanishi, T, Kawanishi, T, Mahmudin, D, Yamamoto, N

    2015 International Symposium on Antennas and Propagation, ISAP 2015    2016.04  [Refereed]

     View Summary

    © 2015 The Institute of Electronics, Information and Comm.We report current research progress on a metamaterial antenna integrated to an optical modulator for millimeter-wave-photonic links. The metamaterial antenna is composed by an array of electric-LC resonators on a LiNbO3 optical crystal. Large millimeter-wave electric field is induced across the capacitive gaps of the resonators due to free-space millimeter-wave irradiation. Optical modulation through Pockels effects can be obtained when light propagates along the capacitive gaps. The integrated device is operated effectively by considering interaction between millimeter-wave and lightwave electric fields along the capacitive gaps. Basic operations of the integrated device for 90GHz millimeter-wave bands are reported and discussed. Optical sidebands with carrier-to-sideband ratio of about ™60dB by millimeter-wave irradiation power of ∼20mW can be experimentally measured using optical spectrum analyzer.

  • Monolithically integrated quantum dot optical modulator with semiconductor optical amplifier for thousand and original band optical communication

    Naokatsu Yamamoto, Kouichi Akahane, Toshimasa Umezawa, Atsushi Matsumoto, Tetsuya Kawanishi

    JAPANESE JOURNAL OF APPLIED PHYSICS   55 ( 4 )  2016.04  [Refereed]

     View Summary

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed with T-band (1.0 mu m waveband) and O-band (1.3 mu m waveband) QD optical gain materials for Gbps-order, high-speed optical data generation. The insertion loss due to coupling between the device and the optical fiber was effectively compensated for by the SOA section. It was also confirmed that the monolithic QD-OGM/SOA device enabled &gt;4.8 Gbps optical data generation with a clear eye opening in the T-band. Furthermore, we successfully demonstrated error-free 4.8 Gbps optical data transmissions in each of the six wavelength channels over a 10-km-long photonic crystal fiber using the monolithic QD-OGM/SOA device in multiple O-band wavelength channels, which were generated by the single QD gain chip. These results suggest that the monolithic QD-OGM/SOA device will be advantageous in ultra-broadband optical frequency systems that utilize the T+O-band for short-and medium-range optical communications. (C) 2016 The Japan Society of Applied Physics

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  • Heterogeneous quantum dot/silicon photonics-based wavelength-tunable laser diode with a 44 nm wavelength-tuning range

    Tomohiro Kita, Naokatsu Yamamoto, Atsushi Matsumoto, Tetsuya Kawanishi, Hirohito Yamada

    JAPANESE JOURNAL OF APPLIED PHYSICS   55 ( 4 )  2016.04  [Refereed]

     View Summary

    A heterogeneous wavelength-tunable laser diode combining quantum dot and silicon photonics technologies is proposed. A compact wavelength-tunable filter with two ring resonators was carefully designed and fabricated using silicon photonics technology. The tunable laser combining the wavelength-tunable filter and an optical amplifier, which includes InAs quantum dots, achieved a 44.0 nm wavelength-tuning range at around 1250 nm. The broadband optical gain of the quantum dot optical amplifier was effectively used by the optimized wavelength-tunable filter. This heterogeneous wavelength-tunable laser diode could become a breakthrough technology for high-capacity data transmission systems. (C) 2016 The Japan Society of Applied Physics

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    19
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  • Characteristics of highly stacked InAs quantum-dot laser grown on vicinal (001)InP substrate

    Kouichi Akahane, Toshimasa Umezawa, Atsushi Matsumoto, Naokatsu Yamamoto, Tetsuya Kawanishi

    JAPANESE JOURNAL OF APPLIED PHYSICS   55 ( 4 )  2016.04  [Refereed]

     View Summary

    We fabricate broad-area laser diodes consisting of 30-layer stacks of InAs quantum dots by using a strain-compensation technique on a vicinal (001)InP substrate. These laser diodes exhibit ground-state lasing at 1576 nm in the pulsed mode with a high characteristic temperature of 111K at around room temperature (20-80 degrees C). (C) 2016 The Japan Society of Applied Physics

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  • B-10-82 Phase-conjugated twin-signals generation by integrated dual-polarization IQ modulators

    Sakamoto Takahide, Lu Guo-Wei, Yamamoto Naokatsu, Kawanishi Tetsuya

    Proceedings of the IEICE General Conference   2016 ( 2 ) 375 - 375  2016.03

    CiNii

  • B-10-45 Common Mode Rejection Ratio (CMRR) Measurement of a Coherent Receiver Using 2 Pairs of 2-Tone Lightwaves

    Inagaki Keizo, Kawanishi Tetsuya, Kanno Atsushi, Yamamoto Nokatsu

    Proceedings of the IEICE General Conference   2016 ( 2 ) 338 - 338  2016.03

    CiNii

  • C-14-14 Optical Frequency Comb Signal Generation Using Electro-Optic Modulator for Low Modulation Index Operation

    Maeda Naoki, Nakamura Ryota, Kawai Tadashi, Enokihara Akira, Yamamoto Naokatsu, Kawanishi Tetsuya

    Proceedings of the IEICE General Conference   2016 ( 1 ) 239 - 239  2016.03

    CiNii

  • C-14-13 Compensation of Third-Order Intermodulation Distortion of Electro-Optic Modulator by Using Frequency Chirp Modulation

    Maeda Sachiko, Kawai Tadashi, Enokihara Akira, Yamamoto Naokatsu, Kawanishi Tetsuya

    Proceedings of the IEICE General Conference   2016 ( 1 ) 238 - 238  2016.03

    CiNii

  • C-14-12 Frequency Chirp Modulation by Electro-optic Modulator and Measurement of Chirp Parameter by Using Chromatic Dispersion of Optical Fiber

    Nakamura Ryota, Yamamoto Katsuyuki, Kawai Tadashi, Enokihara Akira, Yamamoto Naokatsu, Kawanishi Tetsuya

    Proceedings of the IEICE General Conference   2016 ( 1 ) 237 - 237  2016.03

    CiNii

  • C-14-5 EVM Evaluation for doubled 256 QAM signal

    Kaneda Naoki, Yonemoto Naruto, Kawanishi Tetsuya

    Proceedings of the IEICE General Conference   2016 ( 1 ) 230 - 230  2016.03

    CiNii

  • C-14-4 Study of IF over fiber transmission for W-band millimeter-wave signal in a radio over fiber network

    Kanno Atsushi, Dat Pham Tien, Yamamoto Naokatsu, Kawanishi Tetsuya

    Proceedings of the IEICE General Conference   2016 ( 1 ) 229 - 229  2016.03

    CiNii

  • C-4-1 Development of zero-bias operational UTC-PD for photonic wireless communications

    Umezawa T, Kashima K, Kanno A, Akahane K, Matsumoto A, Yamamoto N, Kawanishi T

    Proceedings of the IEICE General Conference   2016 ( 1 ) 205 - 205  2016.03

    CiNii

  • C-3-33 Low Driving-Voltage and Low-Chirp Mach-Zehnder Modulator with Active Y-branch Using Thin LN Substrate

    YAMAGUCHI Yuya, KANNO Atsushi, KAWANISHI Tetsuya, IZUTSU Masayuki, NAKAJIMA Hirochika

    Proceedings of the IEICE General Conference   2016 ( 1 ) 171 - 171  2016.03

    CiNii

  • Pump-phase-noise-free optical wavelength data exchange between QAM signals with 50-GHz channel-spacing using coherent DFB pump

    Lu Guo-Wei, Albuquerque Andre, Puttnam Benjamin J, Sakamoto Takahide, Drummond Miguel, Nogueira Rogerio, Kanno Atsushi, Shinada Satoshi, Wada Naoya, Kawanishi Tetsuya

    OPTICS EXPRESS   24 ( 4 ) 3702 - 3713  2016.02  [Refereed]  [International journal]

     View Summary

    An important challenge for implementing optical signal processing functions such as wavelength conversion or wavelength data exchange (WDE) is to avoid the introduction of linear and nonlinear phase noise in the subsystem. This is particularly important for phase noise sensitive, high-order quadrature-amplitude modulation (QAM) signals. In this paper, we propose and experimentally demonstrate an optical data exchange scheme through cascaded 2nd-order nonlinearities in periodically-poled lithium niobate (PPLN) waveguides using coherent pumping. The proposed coherent pumping scheme enables noise from the coherent pumps to be cancelled out in the swapped data after WDE, even with broad linewidth distributed feedback (DFB) pump lasers. Hence, this scheme allows phase noise tolerant processing functions, enabling the low-cost implementation of WDE for high-order QAM signals. We experimentally demonstrate WDEs between 10-Gbaud 4QAM (4QAM) signal and 12.5-Gbaud 4QAM (16QAM) signal with 3.5-MHz linewidth DFB pump lasers and 50-GHz channel spacing. Error-free operation is observed for the swapped QAM signals with coherent DFB pumping whilst use of free-running DFB pumps leads to visible error floors and unrecoverable phase errors. The phase noise cancellation in the coherent pump scheme is further confirmed by study of the recovered carrier phase of the converted signals. In addition to pump phase noise, the influence of crosstalk caused by the finite extinction ratio in WDE is also experimentally investigated for the swapped QAM signals.

    DOI PubMed

  • Transmission of multiband wireless signals over a seamless IM/DD fiber-MMW system

    Van Nguyen Toan, Dat Pham Tien, Kanno Atsushi, Yamamoto Naokatsu, Bao Vo Nguyen Quoc, Kawanishi Tetsuya

    IEICE Electronics Express   13 ( 15 ) 20160497 - 20160497  2016  [Refereed]

     View Summary

    <p>This paper proposes a high-speed multiband filtered-orthogonal frequency division multiplexing (F-OFDM) signal transmission over a seamless fiber-millimeter-wave (MMW) system at 92.5 GHz. The system employs a frequency and phase stabilized optical MMW signal generation at the transmitter and a simple direct detection at the receiver. We confirm a successful transmission of multiband F-OFDM signal over a seamless 20-km single mode fiber (SMF) and 1-m 92.5-GHz wireless system. Compared to the single-band and multiband OFDM signal transmission, the proposed system can provide a much better performance, particularly at the edges of each band.</p>

    CiNii

  • 5G TRANSPORT NETWORKS: THE NEED FOR NEW TECHNOLOGIES AND STANDARDS

    Dat, Pham Tien, Kanno, Atsushi, Yamamoto, Naokatsu, Kawanishi, Tetsuya

    IEEE COMMUNICATIONS MAGAZINE   54 ( 9 ) 18 - +  2016

  • Low-latency fiber-millimeter-wave system for future mobile fronthauling

    Tien Dat, Pham, Kanno, Atsushi, Yamamoto, Naokatsu, Kawanishi, Tetsuya

    Proceedings of SPIE - The International Society for Optical Engineering   9772  2016.01  [Refereed]

     View Summary

    © 2016 SPIE.A seamless combination of fiber and millimeter-wave (MMW) systems can be very attractive for future heterogeneous mobile networks such as 5G because of its flexibility and high bandwidth. Analog mobile signal transmission over seamless fiber-MMW systems is very promising to reduce the latency and the required band-width, and to simplify the systems. However, stable and high-performance seamless systems are indispensable to conserve the quality of the analog signal transmission. In this paper, we present several technologies to develop such seamless fiber-MMW systems. In the downlink direction, a high-performance system can be realized using a high-quality optical MMW signal generator and a self-homodyne MMW signal detector. In the uplink direction, a cascade of radio-on-radio and radio-over-fiber systems using a burst-mode optical amplifier can support bursty radio signal transmission. A full-duplex transmission with negligible interference effects can be realized using frequency multiplexing in the radio link and wavelength-division multiplexing in the optical link. A high-spectral efficiency MMW-over-fiber system using an intermediate frequency-over-fiber system and a high-quality remote delivery of a local oscillator signal is highly desirable to reduce the costs.

    DOI

    Scopus

    3
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    (Scopus)
  • High-efficiency W-band hybrid integrated photoreceiver module using UTC-PD and pHEMT amplifier

    Umezawa, T, Katshima, K, Kanno, A, Akahane, K, Matsumoto, A, Yamamoto, N, Kawanishi, T, Kawanishi, T

    Proceedings of SPIE - The International Society for Optical Engineering   9747  2016.01  [Refereed]

     View Summary

    © 2016 SPIE.A 100-GHz narrowband photoreceiver module integrated with a zero-bias operational uni-traveling-carrier photodiode (UTC-PD) and a GaAs-based pseudomorphic high-electron-mobility transistor (pHEMT) amplifier was fabricated and characterized. Both devices exhibited flat frequency response and outstanding overall performance. The UTC-PD showed a 3-dB bandwidth beyond 110 GHz while the pHEMT amplifier featured low power consumption and a gain of 24 dB over the 85-100 GHz range. A butterfly metal package equipped with a 1.0 mm (W) coaxial connector and a microstrip-coplanar waveguide conversion substrate was designed for low insertion loss and low return loss. The fabricated photoreceiver module demonstrated high conversion gain, a maximum output power of +9.5 dBm at 96 GHz, and DC-power consumption of 0.21 W.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Free-Space Millimeter-Wave Electro-optic Modulators Using Quasi-Phase-Matching Gap-Embedded-Patch-Antennas on Low Dielectric Constant Substrate

    Yusuf Nur Wijayanto, Atsushi Kanno, Hiroshi Murata, Tetsuya Kawanishi, Naokatsu Yamamoto, Yasuyuki Okamura

    PHOTOPTICS 2015   181   83 - 103  2016  [Refereed]

     View Summary

    Conversion devices between free-space microwave/millimeter-wave and lightwave signals are required in Fiber-Wireless (Fi-Wi) links. In this paper, we propose a free-space millimeter-wave Electro-Optic (EO) modulator using Quasi-Phase-Matching (QPM) gap-embedded-patch-antennas on a low dielectric constant substrate. Free-space millimeter-wave signals can be received and converted directly to lightwave signals using the proposed device. It can be operated passively with no external power supply and operated with extremely low millimeter-wave losses. The QPM array structure can be adopted for improving modulation efficiency by considering the transit-time effects. The proposed device is easy connected to optical fiber, therefore Fi-Wi can be realized using the proposed device. Basic structure, analysis, and experimental results of the proposed device are discussed and reported for 40 GHz operational millimeter-wave bands.

    DOI

    Scopus

  • Full-Duplex Transmission of LTE-A Carrier Aggregation Signal Over a Bidirectional Seamless Fiber-Millimeter-Wave System

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    JOURNAL OF LIGHTWAVE TECHNOLOGY   34 ( 2 ) 691 - 700  2016.01  [Refereed]

     View Summary

    We propose a flexible and high-performance fronthaul system for future mobile networks using a seamless combination of fiber-optic and millimeter-wave (MMW) systems. The proposed system employs a high-quality optical MMW signal generation at the transmitter and a stable and high-performance MMW self-homodyne detection at the receiver. In the downlink direction, successful transmission of intraband and interband carrier aggregation (CA) long-term evolution-advanced (LTE-A) signals over the system is experimentally confirmed. We also confirm satisfactory performance for the transmission over a fiber-wireless bridge using a cascade of the seamless system and a conventional radio-over-fiber (RoF) link. In the uplink direction, we successfully demonstrate the transmission of an intraband CA LTE-A signal over a cascade of a radio-on-radio and a RoF system. In addition, we confirm that the full-duplex transmission of LTE-A signals over the proposed bidirectional system does not experience performance degradation compared to the case with half-duplex transmission. The proposed system is a potential solution for mobile-signal transmission in future networks.

    DOI

    Scopus

    39
    Citation
    (Scopus)
  • Laser-Phase-Fluctuation-Insensitive Optical Coherent Transmission of 16-Quadrature-Amplitude-Modulation Radio-Over-Fiber Signal

    Toshiaki Kuri, Takahide Sakamoto, Tetsuya Kawanishi

    JOURNAL OF LIGHTWAVE TECHNOLOGY   34 ( 2 ) 683 - 690  2016.01  [Refereed]

     View Summary

    A laser-phase-fluctuation-insensitive optical coherent transmission of a 10-Gbaud 16-quadrture-amplitude-modulation radio-over-fiber signal with an offset-frequency-spaced two-tone local light and an digital-signal-processing technique is experimentally demonstrated. Error-free symbol recovery after the 20-km-long fiber-optic transmission is shown and the transmission quality is evaluated.

    DOI

    Scopus

    11
    Citation
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  • On the Channel Capacity of Polarization-Multiplexed Coherent Radio-over-Fiber Transmissions at Millimeter-wave Bands

    Y. Yoshida, Y. Takami, S. Inudo, K. Kitayama, A. Kanno, N. Yamamoto, T. Kawanishi

    2016 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC)     1 - 6  2016  [Refereed]

     View Summary

    A closed-form capacity expression for polarization-multiplexed coherent MIMO radio-over-fiber (RoF) links at millimeter-wave bands is derived and the impact of the fiber's polarization rotation and the wireless antenna misalignment on the MIMO channel capacity is revealed. The analytical results are validated via an indoor W-band (75-110 GHz) 10-Gbaud MIMO-RoF transmission experiment.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • 31-GHz single-carrier, 44.6-Gbps photonic wireless transmission using a wide-bandwidth high power photodetector and a pre-distortion technique

    T. Umezawa, K. Jitsuno, N. Shibagaki, A. Kanno, K. Akahane, A. Mstsumoto, N. Yamamoto, T. Kawanishi

    2016 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2016  [Refereed]

     View Summary

    Single-carrier photonic wireless transmission at 31 GHz and 8.0 Gbaud with 64QAM is successfully achieved with error-free operation. A newly developed wide bandwidth high power photodetector and a pre-equalizing subsystem are presented.

  • All-spectrum fiber-wireless transmission for 5G backhaul and fronthaul links

    Atsushi Kanno, Pham Tien Dat, Naokatsu Yamamoto, Iwao Hosako, Yuki Yoshida, Ken-ichi Kitayama, Tetsuya Kawanishi

    2016 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2016  [Refereed]

     View Summary

    This paper presents the simultaneous transmission of millimeter-wave and terahertz-wave radio signals over an optical fiber and air by a single optical frequency comb source with several types of receiver configurations. (C) 2015 Optical Society of America

  • Mitigation of Modal Crosstalk-induced Power Fading in Mode Division Multiplexed W-Band RoF links

    N. P. Diamantopoulos, Y. Takami, Y. Yoshida, A. Maruta, A. Kanno, N. Yamamoto, T. Kawanishi, R. Maruyama, N. Kuwaki, S. Matsuo, K. Kitayama

    2016 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2016  [Refereed]

     View Summary

    To avoid the modal crosstalk-induced power fading, a mode assignment technique has been proposed and experimentally demonstrated for mode division multiplexed W-band radio-over-fiber links.

  • High-Capacity and High-Spectral-Efficiency Seamless Fiber-Wireless System for High-Speed Trains

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2016 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2016  [Refereed]

     View Summary

    We propose a dual-hop network to high-speed trains by using a seamless fiber-millimeter-wave system for backhaul transmission and a high-speed in-train network. Transmission of a 64-QAM OFDM signal over the cascaded system is successfully confirmed.

  • Radio-over-Fibre Based High-Speed Millimetre-Wave Backhaul System for High-Speed Trains

    Tetsuya Kawanishi, Atsushi Kanno, Pham Tien Dat, Naokatsu Yamamoto

    2016 18TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON)   2016-August   1 - 4  2016  [Refereed]

     View Summary

    This paper reviews train communication networks (TCNs) based on radio-over-fibre (RoF) technology. TCNs connect base stations (BSs) in trains to world wide networks through trackside links consisting of optical fibres and many radio access units (RAUs). Waveform for radio communications can be effectively delivered to each RAU by RoF. The TCN can be controlled by train location information to reduce overhead due to hand-over in mobile communication systems.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • High Conversion Gain 30-110 GHz Photoreceivers for High Data-Rate Advanced Photonic Wireless Communications

    T. Umezawa, K. Jitsuno, A. Kanno, N. Yamamoto, T. Kawanishi

    2016 IEEE Sixth International Conference on Communications and Electronics (ICCE)     389 - 392  2016  [Refereed]

     View Summary

    We report a 30-110 GHz, high conversion gain, and high output photodetector consisting of a hybrid integration of a high-speed photodetector and an RF amplifier with an additional gain emphasis circuit. High data-rate photonic wireless communication over 44 Gbps was demonstrated with a predistortion technique. The minimum optical input power level for an error free operation was also discussed.

    DOI

    Scopus

  • Seamless Access Networks Using Radio-over-Fiber Technology for High-Speed Trains

    Tetsuya Kawanishi, Atsushi Kanno, Pham Tien Dat, Naokatsu Yamamoto

    2016 IEEE Sixth International Conference on Communications and Electronics (ICCE)     381 - 384  2016  [Refereed]

     View Summary

    This paper reviews seamless networks based on radio-over-fiber (RoF) technology. We focus on train communication networks (TCNs) consisting of optical networks and many radio access units (RAUs). Waveform for radio communications can be effectively delivered to each RAU by RoF. The TCN can be controlled by train location information to reduce overhead due to hand-over in mobile communication systems.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Terahertz-Wave Signal Synthesizer for Fiber-Wireless Seamless Access Network

    Atsushi Kanno, Pham Tien Dat, Norihiko Sekine, Akifumi Kasamatsu, Naokatsu Yamamoto, Tetsuya Kawanishi

    2016 IEEE Sixth International Conference on Communications and Electronics (ICCE)     403 - 407  2016  [Refereed]

     View Summary

    A photonic terahertz synthesizer is configured and demonstrated by100-GH, 300-GHz and 600-GHz signal generation. An optical frequency shifter in an amplified optical fiber loop technique configures an optical frequency comb generator with a resultant optical bandwidth up to 2 THz. An observed phase noise characteristic by the photonic synthesizer is considerable for application to the complex modulation formats even in the terahertz bands.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Millimeter-wave Radio-over-fiber System for High-speed Railway Communication

    A. Kanno, P. T. Dat, N. Yamamoto, T. Kawanishi

    2016 PROGRESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM (PIERS)     3911 - 3915  2016  [Refereed]

     View Summary

    We propose an architecture of the radio-over-fiber systems for train communication networks. Prediction-based dynamic optical routing can track the train cars by train location information. High spectral-efficient millimeter-wave signal modulation and demodulation are also discussed with the modulation format and its configuration of the frequency conversions in the paper.

    DOI

    Scopus

    15
    Citation
    (Scopus)
  • Simultaneous Transmission of 4G LTE-A and Wideband MMW OFDM Signals over Fiber Links

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2016 IEEE INTERNATIONAL TOPICAL MEETING ON MICROWAVE PHOTONICS (MWP)     87 - 90  2016  [Refereed]

     View Summary

    We present efficient mobile fronthaul systems for simultaneous transmission of radio signals in the microwave and millimeter-wave hands over fiber links. We compare the performance for signal transmission over intermediate frequency over fiber systems using an electrical and optical up-conversion to the MEW hand at remote sites. We experimentally confirm the successful transmission of an LTE-A signal at 2.6 GHz and a wideband OFDM signal at 35.4 GHz over the systems.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Experimental Demonstration of Fiber-Nonlinearity-Torelant Conjugated-Paired Radio-on-Fiber System Employing Asymmetric Photonic Heterodyne Down-Converter

    Takahide Sakamoto, Guo-Wei Lu, Tetsuya Kawanishi

    2016 IEEE INTERNATIONAL TOPICAL MEETING ON MICROWAVE PHOTONICS (MWP)     51 - 54  2016  [Refereed]

     View Summary

    We experimentally demonstrate fiber-nonlinearity-tolerant conjugated-paired radio-on-fiber (C-RoF) system for the first time. A C-RoF signal is simply generated by dual-sideband modulation and fiber nonlinearity is cancelled through asymmetric photonic heterodyne down-conversion. A QPSK-CRoF signal is transferred over 20-km SMF fiber.

    DOI

    Scopus

  • 92GHz 64QAM Signal Generation by Optical Frequency Doubler

    Naoki Kanada, Naruto Yonemoto, Tetsuya Kawanishi

    2016 IEEE INTERNATIONAL TOPICAL MEETING ON MICROWAVE PHOTONICS (MWP)     145 - 148  2016  [Refereed]

     View Summary

    New communication system for high-speed train passengers is required to provide broadband services in the train. Radio over fiber in millimeter wave band is considered to provide a high throughput of the system. As a proof of concept, we generate 92 GHz 200 M symbol/sec 64QAM signals by optical frequency doubler. EVM of the signal is 7.14%. The result shows 1.2Gbps transmission is available in MMW band by radio over fiber.

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • High-conversion-gain 100-GHz photoreceiver integrated with UTC-PD and PHEMT amplifier for 92-GHz carrier, 10.7-Gbps photonic wireless communication

    T. Umezawa, K. Kashima, A. Kanno, P. T. Dat, K. Akahane, A. Matsumoto, N. Yamamoto, T. Kawanishi

    2016 11TH EUROPEAN MICROWAVE INTEGRATED CIRCUITS CONFERENCE (EUMIC)     468 - 471  2016  [Refereed]

     View Summary

    We successfully designed and fabricated a highconversion-gain 100-GHz photoreceiver integrated with a UTC-PD and a PHEMT amplifier for 92-GHz carrier photonic wireless communication. Then, in a demonstration of 92-GHz carrier, OFDM, 16-QAM photonic wireless communication, we confirmed that high data rate of 11.03-Gbps (bit error rate of 1 x 10(-3)) could be achieved at a low optical input power, without post amplifiers for the photoreceiver. The designs and the results are discussed.

    DOI

    Scopus

  • High speed photoreceiver over 100 GHz and its application

    T. Umezawa, K. Kashima, K. Akahane, A. Matsumoto, A. Kanno, N. Yamamoto, T. Kawanishi

    2016 IEEE PHOTONICS CONFERENCE (IPC)     562 - 563  2016  [Refereed]

     View Summary

    © 2016 IEEE. In wireless communications, the data traffic increases rapidly every year, as well as in fixed optical fiber communications, where the trend for data traffic is not saturated yet. In the next generation of advanced wireless communication services, a high data rate, high capacity, low latency, and low cost are desired. The large radio cover area for present macro-cell should be divided into plenty of small-cells in order to mitigate heavy data traffic in the one macro-cell [1]. Here, radio over fiber (RoF) is a promising technology for access networks such as mobile back-haul and front-haul in wireless communication. High data rate transmission through optical fibers should be introduced near end-user points and be converted to radio signals from simple antennas in small-cells. Here, a high speed photoreceiver is one of key components in RoF communications. On the other hand, power over fiber (PoF) technology, which provides electric power supply through optical fibers, is a compatible technology with a good affinity to RoF technology. The 90 to 110 GHz band is a very attractive frequency band, which involves not only low atmospheric attenuation [2] but also a wider bandwidth compared to that in the microwave region.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Key Technologies for Millimeter-Wave Distributed RADAR System over A Radio Over Fiber Network

    Atsushi Kanno, Toshimasa Umezawa, Toshiaki Kuri, Naokatsu Yamamoto, Yusuf Nur Wijayanto, Tetsuya Kawanishi

    PROCEEDINGS OF 2016 INTERNATIONAL CONFERENCE ON RADAR, ANTENNA, MICROWAVE, ELECTRONICS, AND TELECOMMUNICATIONS (ICRAMET)     1 - 6  2016  [Refereed]

     View Summary

    We discuss key device technologies for realization of an optical-fiber-network-connected distributed radar system in the millimeter-wave band using radio over fiber techniques. The radio over fiber technique is useful for precise signal generation and distribution over the fiber network. In the scenario, each millimeter-wave radar head is not necessary to be equipped with aprecision radar signal source; low cost and low energy consumption radar head will be realized. For connection to the optical network, advanced high-speed optical/electrical converters are developed for signal conversion from/to optical signals in 90-GHz band directly in a central office and each radar head. A signal-to-noise power ratio of generated 90-GHz optical signal was achieved larger than 30 dB: enough quality to use in the radar system. An optical switching technique is useful not only for routing the optical signal to the radar heads but also for filtering unnecessary optical components. These device technologies are applicable for distributed millimeter-wave radar systems.

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • Wireless Millimeter-Wave-Lightwave Signal Converter using Stacked Patch-Antennas Embedded with A Micrometer-Gap and Electro-Optic Crystal

    Hironori Aya, Toshiyuki Inoue, Hiroshi Murata, Yasuyuki Okamura, Yusuf Nur Wijayanto, Atsushi Kanno, Tetsuya Kawanishi

    PROCEEDINGS OF 2016 INTERNATIONAL CONFERENCE ON RADAR, ANTENNA, MICROWAVE, ELECTRONICS, AND TELECOMMUNICATIONS (ICRAMET)     77 - 80  2016  [Refereed]

     View Summary

    We have proposed a new electro-optic signal converter which enables us to convert wireless millimeter-wave signals to Iightwave signals. This is based on a LiNbO3 guided-wave optical modulator combined with vertically-stacked planar patch antennas embedded with a narrow (similar to 5 mu m) gap. Utilizing the stacked structure, the antenna gain, antenna area, and electric field for optical modulation are increased, so that the signal conversion efficiency is increased by 3.65 dB at 60 GHz.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • High-Speed Coherent Transmission Using Advanced Photonics in Terahertz Bands

    Atsushi Kanno, Pham Tien Dat, Norihiko Sekine, Iwao Hosako, Tetsuya Kawanishi, Yuki Yoshida, Ken'ichi Kitayama

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 12 ) 1071 - 1080  2015.12  [Refereed]

     View Summary

    A terahertz-wave communication system directly connected to an optical fiber network is promising for application to future mobile backhaul and fronthaul links. The possible broad bandwidth in the terahertz band is useful for high-speed signal transmission as well as radio-space encapsulation to the high-frequency carrier. In both cases, the low-latency feature becomes important to enhance the throughput in mobile communication and is realized by waveform transport technology without any digital-signal-processing-basedmedia conversion. A highly precise optical frequency comb signal generated by optical modulation and the vector signal demodulation technology adopted from advanced optical fiber communication technologies help perform modulation and demodulation with impairment compensation at just the edges of the link. Terahertz wave, radio over fiber, waveform transport, coherent detection, multilevel modulation, radio on radio.

    DOI

  • Optical frequency-interleaving full-duplex multichannel transmission of W-band frequency-modulated continuous-wave downlink signal and 10-Gb/s on-off-keying uplink signal

    Kiri, Toshiaki, Kanno, Atushi, Kawanishi, Tetsuya, Kawanishi, Tetsuya

    2015 International Topical Meeting on Microwave Photonics, MWP 2015 - Conference Proceedings    2015.12  [Refereed]

     View Summary

    © 2015 IEEE.An optical frequency-interleaving full-duplex multi-channel transmission of W-band frequency-modulated continuous-wave downlink and 10-Gb/s on-off-keying uplink signals is investigated. Two-channel transmission with a flexible wavelength channel selector over 10-km-class fiber-optic network is experimentally demonstrated.

    DOI

    Scopus

  • Advanced photonic ICT devices and their system applications using quantum-dot technology

    Yamamoto, Naokatsu, Akahane, Kouichi, Umezawa, Toshimasa, Matsumoto, Atsushi, Kanno, Atsushi, Kawanishi, Tetsuya, Kawanishi, Tetsuya, Kita, Tomohiro, Yamada, Hirohito

    Asia Communications and Photonics Conference, ACPC 2015    2015.12

     View Summary

    Quantum-dot nanotechnology is attractive for use in advanced photonic devices that will augment the available optical-frequency resources and will increase the number of wavelength channels usable by wired and wireless networks in short/middle-range communication systems. © 2015 OSA.

  • Bias-free high-baud-rate UTC-PD for high-density implementations in parallel photonics

    Umezawa, T, Matsumoto, A, Akahane, K, Kanno, A, Yamamoto, N, Kawanishi, T, Kawanishi, T

    Asia Communications and Photonics Conference, ACPC 2015    2015.12

     View Summary

    We discussed crosstalk issues on parallel photonics assuming high-density integration. RF crosstalk has become a more serious problem than optical crosstalk, and it is affected by the operating frequency (baud rate). A bias free UTC-PD was designed and fabricated. © 2015 OSA.

  • Suppression of optical spectrum fluctuations by stabilizing fiber loop length in optical comb generator using an optical SSB modulator

    Onishi, Yoshiki, Nagatani, Norimasa, Toda, Hiroyuki, Kawanishi, Tetsuya

    2015 International Topical Meeting on Microwave Photonics, MWP 2015 - Conference Proceedings    2015.12  [Refereed]

     View Summary

    © 2015 IEEE.In this paper, we investigate the optical power fluctuation of the output in optical comb generator using an optical single sideband (SSB) modulator with a fiber loop. This fluctuation is caused by undesired sidebands of the SSB modulator. We show that the fluctuation can be suppressed by stabilizing the fiber loop length. In experiment, the averaged peak-to-peak power fluctuation of 23 comb outputs was suppressed from 0.86 dB to 0.13 dB.

    DOI

    Scopus

  • Fiber-remoted 20-Gbaud QPSK transmission at 300 GHz

    Kanno, Atsushi, Sekine, Norihiko, Hosako, Iwao, Kawanishi, Tetsuya, Kawanishi, Tetsuya, Yoshida, Yuki, Kitayama, Ken Ichi

    2015 International Topical Meeting on Microwave Photonics, MWP 2015 - Conference Proceedings    2015.12  [Refereed]

     View Summary

    © 2015 IEEE.300-GHz multilevel signal transmission over optical fibers and air is demonstrated using advanced optical communication technology including optical frequency comb generation. Local oscillator signal transport over optical fibers to optical-terahertz converters removes the need for setting any terahertz-capable oscillators in the converters. This fiber-remoted configuration with seamless conversion between the optical and terahertz signals is compatible with high-speed terahertz backhaul and fronthaul links.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • High conversion gain, low power consumption W-band photoreceiver integrated with UTC-PD and InP-PHEMT amplifier

    Umezawa, T, Akahane, K, Kanno, A, Yamamoto, N, Kashima, K, Kawanishi, T, Kawanishi, T

    2015 International Topical Meeting on Microwave Photonics, MWP 2015 - Conference Proceedings    2015.12  [Refereed]

     View Summary

    © 2015 IEEE.In this study, we successfully fabricated a W-band high-power photoreceiver with high output power and low power consumption. This W-band photoreceiver was integrated with a bias-free uni-travelling carrier photodetector (UTC-PD) and an InP high electron mobility transistor (PHEMT) amplifier for the first time. An ultrabroad 3 dB bandwidth beyond 110 GHz in an UTC-PD and maximum oscillation frequency of 320 GHz in a PHEMT low-noise amplifier were used for this hybrid integration. At 109 GHz, a high radio frequency output power of +10 dBm, high transimpedance gain of 828 □, and low power consumption of 67 mW was achieved in an optical-electrical converting process.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Low-latency fiber-wireless bridge for flexible fronthauling in future mobile networks

    Dat, Pham Tien, Kanno, Atsushi, Kawanishi, Tetsuya

    European Microwave Week 2015:     305 - 308  2015.12  [Refereed]

     View Summary

    © 2015 EuMA.We propose a flexible and low-latency cascaded fiber-wireless system for future mobile fronthauling using seamless combination of fiber-optic and millimeter-wave links. Successful transmission of intraband and interband carrier aggregation LTE-A signals over the system is experimentally confirmed. Satisfactory performance is achieved owing to the use of a high-quality optical millimeter-wave signal generation technique at the transmitter and a proposed high-performance self-homodyne detection at the receiver.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • 300-GHz versatile transceiver front-end for both communication and imaging

    Kanno, A, Sekine, N, Uzawa, Y, Hosako, I, Kawanishi, T, Kawanishi, T

    IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves    2015.11  [Refereed]

     View Summary

    © 2015 IEEE.Envelope-detector-based transceiver configurations are useful for both digital signal transmission and radar systems in the terahertz band. A dual-purpose transceiver is demonstrated using a 1-Gb/s on-off keying signal and 12.5-GHz-bandwidth frequency-modulated continuous-wave radar.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Analog signal transmission by FPGA-based pseudo-delta-sigma modulator

    Kanno, Atsushi, Kawanishi, Tetsuya, Kawanishi, Tetsuya

    2015 IEEE Photonics Conference, IPC 2015     136 - 137  2015.11  [Refereed]

     View Summary

    © 2015 IEEE.We present a pseudo-delta-sigma modulator and demonstrate transmission using an advanced modulation. This digitally implemented transmitter helps in reducing the complexity at the receiver and realizing waveform transport over a digital optical network.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Optical frequency-interleaving full-duplex transmission of 96-GHz-band frequency-modulated continuous-wave downlink signal and 10-Gb/s on-off-keying uplink signal

    Kuri, Toshiaki, Kanno, Atsushi, Kawanishi, Tetsuya, Kawanishi, Tetsuya

    2015 IEEE Photonics Conference, IPC 2015     148 - 149  2015.11  [Refereed]

     View Summary

    © 2015 IEEE.An optical frequency-interleaving full-duplex transmission of 96-GHz-band frequency-modulated continuous-wave downlink signal and 10-Gb/s on-off-keying uplink signals is investigated. The proposed full-duplexing transmission with a flexible wavelength channel selector over 10-km fiber-optic link is experimentally demonstrated.

    DOI

    Scopus

  • RADIO-ON-RADIO-OVER-FIBER: EFFICIENT FRONTHAULING FOR SMALL CELLS AND MOVING CELLS

    Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    IEEE WIRELESS COMMUNICATIONS   22 ( 5 ) 67 - 75  2015.10  [Refereed]

     View Summary

    A combination of fiber and radio links would be attractive for efficient fronthauling to small cells and moving cells. However, achieving connectivity by using wired-wireless media converters significantly increases system complexity, power consumption, and latency. A seamless combination of fiber and radio links in which photonics-based technologies are used to generate and transmit radiowave signals is more suitable. In this article, we present an overview of fiber-radio link combination for mobile signal transmission. We propose an efficient solution for future mobile fronthauling based on the analog transmission of mobile signals over a bidirectional seamless system. We discuss the potential as well as the challenges and perspectives of the systems applied for mobile fronthauling in small-cell-and moving-cell-based networks. We also present a proof-of-concept demonstration of the transmission of mobile signals over the system. Satisfactory performance is obtained for different high-speed advanced signals. The transmission range over fiber links and the estimated range of the radio links are sufficiently long to facilitate the practical implementation of the system. The system is scalable to include new deployments of small cells and wireless services using wavelength-division and subcarrier multiplexing techniques. It can provide a high-speed, low-latency, and flexible solution for fronthauling in new emerging wireless systems such as 5G networks.

    DOI

    Scopus

    65
    Citation
    (Scopus)
  • Laser-phase-fluctuation-insensitive offset-frequency-spaced two-tone optical coherent detection scheme and its transmission for radio-over-fiber systems

    Toshiaki Kuri, Takahide Sakamoto, Tetsuya Kawanishi

    OPTICS EXPRESS   23 ( 19 ) 24140 - 24151  2015.09  [Refereed]  [International journal]

     View Summary

    We propose a new optical coherent detection scheme with a "two-tone" local light, which is also in principle insensitive to the laser phase fluctuation and is assisted by the digital signal processing technique for radio-over-fiber (RoF) systems. The main feature of our proposal is that the frequency separation of the two-tone local light is different from that of the RoF signal, which is called "offset-frequency-spaced" in this paper. First, we explain the principle of our new proposal and experimentally demonstrate the data recovery. Then, the influence of the frequency detuning between photo-detected modulated and unmodulated signals is discussed. Moreover, the transmission performance with an error vector magnitude (EVM) is evaluated for the optical coherent detection of a 10-Gbaud quadrature-phase-shift-keying RoF signal after a 20-km-long standard single-mode fiber transmission. (C) 2015 Optical Society of America

    DOI PubMed

  • Low Chirp Modulation by Electro-Optic Intensity Modulator Using Microwave 180-Degree Hybrid Directly Formed on LiNbO3 Substrate

    Akira Enokihara, Masashi Yamamoto, Tadashi Kawai, Tetsuya Kawanishi

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 8 ) 777 - 782  2015.08  [Refereed]

     View Summary

    An electro-optic (EO) modulator integrated with the microwave planar circuit directly formed on a LiNbO3 (LN) substrate for low frequency-chirp performance and compact configuration is introduced. Frequency chirp of EO intensity modulators was investigated and a dual-electrode Mach-Zehnder (MZ) modulator combined with a microwave rat-race (RR) circuit was considered for the low-chirp modulation. The RR circuit, which operates as a 180-degree hybrid, was designed on a z-cut LN substrate to create two modulation signals of the same amplitude in anti-phase with each other from a single input signal. Output ports of the RR were connected to the modulation electrodes on the substrate. The two signals of the equal amplitude drive two phase modulation parts of the modulator so that the symmetric interference are realized to obtain intensity modulation of low frequency-chirp. The modulator was designed and fabricated on a single LN substrate for around 10 GHz modulation frequencies and 1550 nm light wavelength. The chirp parameters were measured to be less than 0.2 in the frequency range between 8 and 12 GHz. By compensating imbalance of the light power splitting in the waveguide MZ interferometer the chirp could be reduced even more.

    DOI

  • Compact Electro-Optic Single Sideband Modulators Utilizing Miniaturized Branch-Line Couplers on LiNbO3 Substrate

    Katsuyuki Yamamoto, Tadashi Kawai, Akira Enokihara, Tetsuya Kawanishi

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 8 ) 769 - 776  2015.08  [Refereed]

     View Summary

    Optical single sideband (SSB) modulation with the Mach-Zehnder (MZ) interferometer was realized by integrating the modulation electrode with the branch-line coupler (BLC) as a 90-degree hybrid onto the modulator substrate. In this paper, BLCs of the microsrtip-line structure were miniaturized on modulator substrates, LiNbO3 (LN), to realize more compact optical SSB modulators. We introduced two techniques of miniaturizing the BLC, one is using periodically installed open-circuited stabs and the other is installing series capacitors. Compared with a conventional pattern of the BLC, an area of the miniaturized BLC by using periodically installed open-circuited stubs was reduced to about 50%, and that by installing series capacitors was done to about 60%. The operation of these miniaturized BLCs was experimentally confirmed as the 90-degree hybrid at around 10GHz. Output ports of each miniaturized BLC were directly connected with the modulation electrode on the modulator substrate. Thereby, we fabricated two types of compact SSB modulators for 1550nm light wavelength. In the experiments, the optical SSB modulation was successfully confirmed by the output light spectra and the sideband suppression ratio of more than 30dB were observed.

    DOI

  • Generation of Arbitrarily Patterned Pulse Trains in the THz Range by Spectral Synthesis of Optical Combs

    Morohashi Isao, Sakamoto Takahide, Sekine Norihiko, Kawanishi Tetsuya, Kasamatsu Akifumi, Hosako Iwao

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 8 ) 793 - 798  2015.08  [Refereed]

    DOI

  • Optical 8QAM and 8PSK synthesis by cascading arbitrary 2QAM with squared QPSK

    Guo-Wei Lu, Jose Manuel Delgado Mendinueta, Takahide Sakamoto, Naoya Wada, Tetsuya Kawanishi

    OPTICS EXPRESS   23 ( 16 ) 21366 - 21374  2015.08  [International journal]

     View Summary

    In dynamic optical networking scenarios, it is desirable that the optical transmitter chooses the most suitable modulation format in order to achieve optimal transmission performance. Owing to the ability of switching among different modulation formats, flexible optical transmitters based on reconfigurable optical devices are becoming a key component for the implementation of future flexible optical networks. In this paper, we experimentally demonstrate a flexible 8-ary transmitter to achieve adaptive switching between 8-ary phase-shift keying (8PSK) and circular 8-ary quadrature-amplitude modulation (8QAM) through reconfiguration of two cascaded in-phase/quadrature (IQ) modulators with different driving signals and biasing conditions. An arbitrary binary quadrature-amplitude modulation (2QAM) with constant or non-constant amplitude is proposed and experimentally demonstrated using an IQ modulator. Then, optical 8PSK or 8QAM modulation formats are successfully synthesized when a standard squared QPSK modulator is cascaded with a constant-amplitude or non-constant-amplitude 2QAM, respectively. (C) 2015 Optical Society of America

    DOI PubMed

  • Re-Configurable Wavelength De-Multiplexer in Wavelength Division Multiplexed Radio-over-Fiber Systems for Frequency-Modulated Continuous-Wave Signal Delivery

    Toshiaki Kuri, Atsushi Kanno, Tetsuya Kawanishi

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 8 ) 849 - 856  2015.08  [Refereed]

     View Summary

    A re-configurable wavelength de-multiplexer for wave-length-division-multiplexed (WDM) radio-over-fiber (RoF) systems, which is specially designed for delivering frequency-modulated continuous-wave (FM-CW) signals, is newly developed. The principle and characteristics of the developed de-multiplexer are described in detail. Then the de-multiplexing performances of 4-channel WDM 32-GHz-band, 8-channel WDM 48-GHz-band, and 5-channel WDM 96-GHz-band FM-CW RoF signals are evaluated with the de-multiplexer.

    DOI

  • Performance of Uplink Packetized LTE-A Signal Transmission on a Cascaded Radio-on-Radio and Radio-over-Fiber System

    Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 8 ) 840 - 848  2015.08  [Refereed]

     View Summary

    In this paper, we propose a flexible and high-capacity front-haul link for the uplink transmission of high-speed mobile signals using a cascade of radio-on-radio (RoR) and radio-over-fiber (RoF) systems. To emulate the cases that may occur in the uplink direction, we experimentally investigate the performance of superposing an uplink bursty LTE-A signal on the cascaded system using optical packet signal transmission. The performance of systems using different types of erbium-doped fiber amplifiers (EDFAs), including a high-transient EDFA, an automatic-gain-control EDFA, and a burst-mode (BM) EDFA is evaluated and compared. We confirm that the dynamic transience of the EDFAs has a significant influence on the signal performance. By using a BM-EDFA, we confirm successful transmission of the uplink packetized LTE-A signal on the cascaded system. Both the measured error vector magnitude and the received optical power range metrics exceed the requirements. We also estimate the maximum transmission range of the RoR link, and it is confirmed that a sufficiently long range could be achieved for the applications in mobile front-haul networks.

    DOI

  • New Burst-Mode Erbium-Doped Fiber Amplifier with Wide Linearity and High Output Power for Uplink Analog Radio-over-Fiber Signal Transmission

    Masaki Shiraiwa, Yoshinari Awaji, Naoya Wada, Atsushi Kanno, Toshiaki Kuri, Pham Tien Dat, Tetsuya Kawanishi

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 8 ) 832 - 839  2015.08  [Refereed]

     View Summary

    We report the adaptability of the burst-mode erbium-doped fiber amplifier (BM-EDFA) for uplink transmission of sharply rising analog radio-over-fiber (RoF) signals by using long-term evolution (LTE) -Advanced format on a mobile front-haul. Recent drastically increased mobile data traffic is boosting the demand for high-speed radio communication technologies for next-generation mobile services to enhance user experience. However, the latency become increasingly visible as serious issues. Analog RoF technology is a promising candidate for a next generation mobile front-haul to realize low latency. For the uplink, an RoF signal may rise sharply in response to a burst of in-coming radio signals. We propose that a newly developed BM-EDFA is applied for such a sharply rising RoF signal transmission. The BM-EDFA that we designed using enhanced intrinsic saturation power EDF to suppress the gain transient caused by received optical power fluctuations with optical feedback. The new BM-EDFA was designed for a wider linear output power range and lower NF than the previous BM-EDFA. The observed range of received optical power satisfying an error vector magnitude of less than 8%rms achieved over 16 dB. We consider that our BM-EDFAs with wide linear ranges of output power will be a key device for the LTE-Advanced RoF uplink signal transmission via optical access networks for the next-generation mobile front-haul.

    DOI

  • A 1.55-mu m Waveband Optical Absorption Characterization of an Electro-Absorption Device with a Highly Stacked InAs/InGaAlAs Quantum Dot Structure

    Yamamoto Naokatsu, Akahane Kouichi, Umezawa Toshimasa, Kawanishi Tetsuya

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 8 ) 878 - 881  2015.08  [Refereed]

    DOI

  • Millimeter-Wave Radar Receiver Using Z-Cut LiNbO3 Optical Modulator with Orthogonal-Gap-Embedded Patch-Antennas on Low-k Dielectric Material

    Yusuf Nur Wijayanto, Atsushi Kanno, Hiroshi Murata, Tetsuya Kawanishi, Yasuyuki Okamura

    IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 8 ) 783 - 792  2015.08  [Refereed]

     View Summary

    A millimeter-wave radar receiver using a z-cut LiNbO3 optical modulator with orthogonal-gap-embedded patch-antennas on a low-k dielectric material is proposed. A millimeter-wave from a reflected radar signal can be received by the patch-antennas and converted directly to a lightwave through electro-optic modulation. A low-k dielectric material is used as a substrate for improving antenna gain. Additionally, an interaction length between millimeter-wave and lightwave electric fields becomes long. As a result, large modulation efficiency can be obtained, which is proportional to sensitivity of the millimeter-wave radar receiver. Optical millimeter-wave radar beam-forming can be obtained using the proposed device with meandering-gaps for controlling interaction between millimeter-wave and lightwave electric fields in electro-optic modulation. Analysis and experimentally demonstration of the proposed device are discussed and reported for 40GHz millimeter-wave bands. Optical millimeter-wave radar beam-forming in 2-D is also discussed.

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • Pure single-sideband modulation using high extinction-ratio parallel Mach-Zehnder modulator with third-order harmonics superposition technique

    Yamaguchi, Yuya, Kanno, Atsushi, Kawanishi, Tetsuya, Izutsu, Masayuki, Izutsu, Masayuki, Nakajima, Hirochika

    Conference on Lasers and Electro-Optics Europe - Technical Digest   2015-August  2015.08  [Refereed]

     View Summary

    © 2015 OSA. We demonstrate high spurious suppression ratio single-sideband modulation by a high extinction-ratio parallel Mach-Zehnder modulator. An electrical third-order nonlinearity suppression technique can enhance the suppression ratio as high as 47 dB.

  • B-10-24 Measurement of Time-Frequency Domain Multiplexed Signal by Loop-Assisted Coherent Matched Detector

    Sakamoto Takahide, Lu Guo-Wei, Kawanishi Tetsuya

    Proceedings of the Society Conference of IEICE   2015 ( 2 ) 188 - 188  2015.08

    CiNii

  • B-2-17 Trial of Bird Detection by FOD Detection Radar on Airport Surface

    Yonemoto Naruto, Shibagaki Nobuhiko, Kashima Kenichi, Haramoto Ryoki, Sato Yosuke, Inagaki Keizo, Kawanishi Tetsuya

    Proceedings of the Society Conference of IEICE   2015 ( 1 )  2015.08

    CiNii

  • C-14-17 Improvement of Modulation Efficiency of Electro-Optic Modulators with Gap-Embedded Patch Antenna Utilizing Stacked Structure

    Aya Hironori, Wijayanto Yusuf Nur, Kanno Atsushi, Kawanishi Tetsuya, Murata Hiroshi, Okamura Yasuyuki

    Proceedings of the Society Conference of IEICE   2015 ( 1 ) 183 - 183  2015.08

    CiNii

  • Sub-THz radio-over-fiber signal generation using external modulation

    Tetsuya Kawanishi, Takahide Sakamoto, Atsushi Kanno

    IEICE ELECTRONICS EXPRESS   12 ( 13 ) 20152004 - 20152004  2015.07  [Refereed]

     View Summary

    This paper describes photonic technologies for millimeter-wave generation and distribution. External modulation would be useful for stable and high-quality radio-over-fiber signal generation, where frequency stability and spurious suppression are very important for radio services such as mobile communications, radio locations etc. This paper provides outline of radio-over-fiber signal generation techniques. Precise and high-speed light-wave optical modulation would play important roles for suppression of undesired spectrum components. Photonic harmonic generation would be useful for very high-frequency signals. Reciprocating optical modulators consisting of optical modulators and fiber Bragg gratings can provide optical modulation by sub-THz signals.

    DOI CiNii

    Scopus

    3
    Citation
    (Scopus)
  • Optical Comb-based Versatile Wavelength Division Multicasting Add-drop Node for Efficient WDM Networks

    Jun Sakaguchi, Takahide Sakamoto, Atsushi Kanno, Yoshinari Awaji, Naoya Wada, Tetsuya Kawanishi

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     Th2A.6 - 3  2015.03  [Refereed]

    DOI

  • Long Distance Transmission in a Multi-Core Fiber with Self-Homodyne Detection

    Benjamin J, Puttnam, Ruben S. Luís, José-Manuel Delgado Mendinueta, Jun Sakaguchi, Werner Klaus, Yoshinari Awaji, Naoya Wada, Atsushi Kanno, Tetsuya Kawanishi

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     Th1D.5 - 3  2015.03  [Refereed]

    DOI

  • C-3-70 Extinction-Ratio and Chirp Tunable Mach-Zehnder Modulator

    YAMAGUCHI Yuya, NAKAJIMA Shinya, KANNO Atsushi, KAWANISHI Tetsuya, IZUTSU Masayuki, NAKAJIMA Hirochika

    Proceedings of the IEICE General Conference   2015 ( 1 ) 194 - 194  2015.02

    CiNii

  • On the MIMO channel rank deficiency in W-band MIMO RoF transmissions.

    S. Inudo, Yuki Yoshida, Atsushi Kanno, Pham Tien Dat, Tetsuya Kawanishi, Ken-ichi Kitayama

    Optical Fiber Communications Conference and Exhibition(OFC)     1 - 3  2015

    DOI

  • Mode-division multiplexed W-Band RoF transmission for higher-order spatial multiplexing.

    Nikolaos-Panteleimon Diamantopoulos, S. Inudo, Yuki Yoshida, Akihiro Maruta, Atsushi Kanno, Pham Tien Dat, Tetsuya Kawanishi, Ryo Maruyama, N. Kuwaki, Shinji Matsuo, Ken-ichi Kitayama

    Optical Fiber Communications Conference and Exhibition(OFC)     1 - 3  2015

    DOI

  • WDM RoF-MMW and linearly located distributed antenna system for future high-speed railway communications.

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    IEEE Communications Magazine   53 ( 10 ) 86 - 94  2015

    DOI

  • Pump-Phase-Noise-Tolerant Wavelength Multicasting for QAM Signals using Flexible Coherent Multi-Carrier Pump

    Guo-Wei Lu, Takahide Sakamoto, Tetsuya Kawanishi

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2015  [Refereed]

     View Summary

    We propose and demonstrate pump-phase-noise-tolerant 1-to-7 wavelength multicasting for QAM signals using flexible coherent multi-carrier pump. Less than 0.8dB penalty is obtained after multicasting with the elimination of phase noise from pump using coherent pumping.

  • Multifunctional All-optical Signal Processing Scheme for Simultaneous Multichannel WDM Multicast and XOR Logic Gates Based on FWM in QD-SOA

    Danshi Wang, Min Zhang, Guo-Wei Lu, Jun Qin, Takahide Sakamoto, Kouichi Akahane, Naokatsu Yamamoto, Tetsuya Kawanishi, Ze Li, Yue Cui

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2015  [Refereed]

     View Summary

    Through FWM in our fabricated QD-SOA and without additional pumps, three 1-to-3 WDM multicasts and three XOR logic gates are simultaneously realized for three 10 Gbps NRZ-DPSK signals. The error-free performance is achieved for all of the signals and the power penalties are &lt; 1.3 dB at BER of 10(-9).

    DOI

  • Laser-Phase-Fluctuation-Insensitive Optical Coherent Transmission of 16-QAM Radio-over-Fiber Signal with Offset-Frequency-Spaced Two-Tone Local Light

    Toshiaki Kuri, Takahide Sakamoto, Tetsuya Kawanishi

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2015  [Refereed]

     View Summary

    A digital-signal-processing-assisted and laser-phase-fluctuation-insensitive optical coherent transmission of a 10-Gbaud 16-quadrture-amplitude-modulation radio-over-fiber signal with an offset-frequency-spaced two-tone local light is experimentally demonstrated. Error-free symbol recovery after the 20-km-long fiber-optic transmission is shown.

    DOI

  • Bias free operational 107-Gbaud ultra-fast photodetector

    T. Umezawa, K. Akahane, N. Yamamoto, A. Kanno, T. Kawanishi

    ECOC 2015 41ST EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION     1 - 3  2015  [Refereed]

     View Summary

    We designed a high-baud-rate UTC photodetector without a bias circuit for the first time. The photodetector's wideband frequency response over 100 GHz and clear eye diagrams up to 107 Gbaud were confirmed at 0 V. Bit error rate is discussed for 56 Gbaud and 107 Gbaud.

    DOI

  • Zero-Bias Operational Ultra-Broadband UTC-PD above 110 GHz for High Symbol Rate PD-Array in High-Density Photonic Integration

    T. Umezawa, K. Akahane, N. Yamamoto, A. Kanno, K. Inagaki, T. Kawanishi

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2015  [Refereed]

     View Summary

    We have successfully developed a zero-bias operational ultra-broadband uni-travelingcarrier photodiode (UTC-PD) with a frequency bandwidth above 110 GHz using a low carrier concentration of 3 x 10(14) cm(-3) in the carrier collection layer.

  • High-Speed and Low-Latency Front-haul System for Heterogeneous Wireless Networks Using Seamless Fiber-Millimeter-Wave

    Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC)     994 - 999  2015  [Refereed]

     View Summary

    We propose a novel high-capacity and low-latency front-haul system for small cells-based heterogeneous wireless networks. We experimentally demonstrate a proof-of-concept seamless convergence of radio-over-fiber (RoF) and millimeter-wave (MMW) system at 90 GHz for high-speed wireless signal transmission. Simultaneous transmission and demodulation of standard-compliant very-high-throughput WLAN IEEE 802.11ac and high-speed LTE-A signals over the system are successfully confirmed for the downlink direction. Satisfactory transmission performance over the converged 10-km RoF and a 5-m 90-GHz wireless link is achieved. The measured root-mean-square error vector magnitude is much better than the requirement defined by the standards.

    DOI

  • Monolithically Integrated Quantum-Dot Optical Modulator with Semiconductor Optical Amplifier for 1.3-mu m Waveband Error-free 10-km-long Transmission

    Naokatsu Yamamoto, Kouichi Akahane, Toshimasa Umezawa, Tetsuya Kawanishi

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2015  [Refereed]

     View Summary

    A monolithically integrated quantum-dot (QD) optical gain modulator with semiconductor optical amplifier was developed for successful demonstration of error-free Gb/s-order high-speed, 10-km-long transmissions using 1.3-mu m multiple wavelength channels from a QD comb laser.

  • Experimental Evaluation of the Time and Frequency Crosstalk Dependency in a 7-Core Multi-Core Fiber

    Ruben S. Luis, Benjamin J. Puttnam, Werner Klaus, Jose Manuel Delgado Mendinueta, Yoshinari Awaji, Naoya Wada, Atsushi Kanno, Tetsuya Kawanishi, Tetsuya Nakanishi, Tetsuya Hayashi, Takashi Sasaki

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2015  [Refereed]

     View Summary

    We experimentally evaluate the time-varying crosstalk frequency response of a multicore fiber. Our findings suggest that dynamically adaptive transmission would be able to exploit this behavior, to improve the performance of crosstalk-limited links.

    DOI

  • Bidirectional Transmission of LTE-A Carrier Aggregation Signal over a Seamless Fiber-Wireless System in W-Band

    Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2015  [Refereed]

     View Summary

    We present a high-speed and low-latency seamless fiber-millimeter-wave system for future mobile front-haul networks. The bidirectional transmission of a downlink interband and an uplink intraband carrier aggregation LTE-A signal over the system is successfully demonstrated.

  • 10-Gb/s Wireless Signal Transmission over a Seamless IM/DD Fiber-MMW System at 92.5 GHz

    Tu Lam Thanh, Vo Nguyen Quoc Bao, Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC)     1364 - 1369  2015  [Refereed]

     View Summary

    In this paper, we propose a high-speed wireless signal transmission over a simple analog intensity modulation/ direct detection (IM/DD) fiber-millimeter-wave (MMW) system at 92.5 GHz. The system employs a frequency and phase stabilized optical MMW signal generation at transmitter and a simple direct detection at receiver. We confirm a successful transmission of 10Gb/s 16-QAM OFDM-based wireless signal over a seamless 8-km SMF and 27-cm 92.5-GHz wireless system. To further increase the fiber transmission range, we use a simple adaptive modulation approach. Successful transmission over 10-km single mode fiber (SMF) system is confirmed for a 8.1 Gb/s wireless signal using both 16-QAM and QPSK modulation. We also estimate the maximum transmission range for the MMW link, and it is proved that a transmission over a 1-km MMW link can be achieved. Both the confirmed fiber length and estimated MMW range are sufficiently long for future mobile front-haul systems in next generation wireless networks. The system therefore can provide a high-speed, low-latency, and flexible solution for front-hauling in new emerging wireless systems such as 5G mobile networks.

    DOI

  • Loop-Assisted Multi-Input-Multi-Output Coherent Matched Detector for Ultra High-Bandwidth Parallel Optical Time-Frequency Domain Sampling

    Takahide Sakamoto, Guo-Wei Lu, Tetsuya Kawanishi

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2015  [Refereed]

     View Summary

    We demonstrate loop-assisted multi-input-multi-output coherent matched detector, enabling ultra-wideband parallel optical sampling in time-frequency domain. 8-subchannels packed in 80 GHz in single polarization was simultaneously captured in parallel only using a single 10-Gbaud coherent receiver.

    DOI

  • Advanced Photonics for Wired and Wireless Seamless Networks

    Tetsuya Kawanishi, Atsushi Kanno, Pham Tien Dat, Atsushi Matsumoto, Naokatsu Yamamoto

    2015 17th International Conference on Transparent Optical Networks (ICTON)     1 - 4  2015  [Refereed]

     View Summary

    Wired and wireless seamless networks comprised of optical-fiber and radio-wave links can provide high-speed, resilient, and flexible broadband services, one of the important requirements for which is the precise and highspeed control of light waves based on advanced photonic technologies such as digital coherent detection, highspeed electro-optic conversion, and radio-over-fiber. In this paper, we focus on advanced photonic devices for optical and radio-wave links and on the expected performance and function of seamless networks.

    DOI

  • Oppositely-Biased Dual-polarization IQ Modulators for Nonlinearity-Tolerant Polarization-Multiplexed Phase-Conjugated Twin-Signals Generation

    Takahide Sakamoto, Guo-Wei Lu, Tetsuya Kawanishi

    ECOC 2015 41ST EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION   2015-November   1 - 3  2015  [Refereed]

     View Summary

    We experimentally demonstrate generation of polarization-multiplexed phase-conjugated twin signals by using oppositely-biased dual-polarization IQ modulators, compensating for nonlinear signal distortion in fiber transmission. Bias condition is optimized investigating nonlinearity tolerance of the generated signals transmitted over SMF.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • High-Spectral Efficiency Millimeter Wave-over-Fiber System for Future Mobile Fronthaul

    Pham Tien Dat, Atsushi Kanno, Keizo Inagaki, Naokatsu Yamamoto, Tetsuya Kawanishi

    ECOC 2015 41ST EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION   2015-November   1 - 3  2015  [Refereed]

     View Summary

    We present a high-spectral efficiency fronthaul system for the transmission of millimeter-wave and multiple-input multiple-output (MIMO) signals in future mobile networks. The transmission of an interband carrier aggregation and a 2 x 2 MIMO LTE-A signal over the system is successfully demonstrated.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Low-Latency Fiber-Wireless Bridge for Flexible Fronthauling in Future Mobile Networks

    Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    2015 45TH EUROPEAN MICROWAVE CONFERENCE (EUMC)     1156 - 1159  2015  [Refereed]

     View Summary

    We propose a flexible and low-latency cascaded fiber-wireless system for future mobile fronthauling using seamless combination of fiber-optic and millimeter-wave links. Successful transmission of intraband and interband carrier aggregation LTE-A signals over the system is experimentally confirmed. Satisfactory performance is achieved owing to the use of a high-quality optical millimeter-wave signal generation technique at the transmitter and a proposed high-performance self-homodyne detection at the receiver.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • 300-GHz FM-CW radar system by optical frequency comb generation

    Atsushi Kanno, Norihiko Sekine, Yoshinori Uzawa, Iwao Hosako, Tetsuya Kawanishi

    2015 45TH EUROPEAN MICROWAVE CONFERENCE (EUMC)     558 - 561  2015  [Refereed]

     View Summary

    In this paper, we demonstrate a 300-GHz FM-CW radar using optical modulation technology. An optical frequency comb based on the optical modulation is utilized as a broadband frequency multiplier with a factor of 12. At a central frequency of 300 GHz, we generate a 12-GHz-bandwidth FM-CW signal with a pulse duration of 10 mu s, realizing a precise ranging with a resolution of several centimeters. We show that the optical frequency comb generator is capable of generating larger bandwidth FM-CW signals.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • FIBER-REMOTED 96-GHz RADAR SYSTEM

    Atsushi Kanno, Tetsuya Kawanishi

    2015 IEEE AVIONICS AND VEHICLE FIBER-OPTICS AND PHOTONICS CONFERENCE (AVFOP)     59 - 60  2015  [Refereed]

     View Summary

    © 2015 IEEE.High-precision imaging technology and its application are highly demanded for the enhancement of civil security. They are used to help prevent major incidents in railways or airports. In these applications, both small object detection and high-range resolution are key features. As far as the detectable target size is concerned, a high-frequency carrier is indispensable in radar systems. However, a radio signal with millimeter-wave (high frequency) suffers from large atmospheric attenuation. For example, the attenuation coefficient at 90 GHz is estimated to be 1 dB/km, while it is less than 0.1 dB/km in microwave bands [1]. Thus, the radar signal will have to originate from an area close to the target. Setting up a radar system with a synthesizer close to the target might not be desirable because a high-precision electrical synthesizer is generally large and consumes high energy. Radio-over-fiber (RoF) technology, used to transport the signal over optical fibers, is a promising candidate to deliver the millimeter-wave signal to the suitable point over a low-loss optical fiber cable. Radars utilizing the RoF technology have already been reported; however, digital signal processing in remote radar heads was required to reduce large transmission data [2, 3].

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • 5G TRANSPORT AND BROADBAND ACCESS NETWORKS: THE NEED FOR NEW TECHNOLOGIES AND STANDARDS

    Pham Tien Dat, Atsushi Kanno, Naokatsu Yamamoto, Tetsuya Kawanishi

    2015 ITU Kaleidoscope: Trust in the Information Society (K-2015)     159 - 166  2015  [Refereed]

     View Summary

    In addition to new radio technologies, end-to-end transport networks will play a vital role in future 5G (and beyond) networks. In particular, access transport networks connecting radio access with core networks are of critical importance. They should be able to support massive connectivity, super high data rates, and real time services in a ubiquitous environment. To attain these targets, transport networks should be constructed on the basis of a variety of technologies and methods, depending on application scenarios, geographical areas, and deployment models. In this paper, we present several technologies, including analog radio-over-fiber transmission, intermediate-frequency-over-fiber technology, radio-on-radio transmission, and the convergence of fiber and millimeter-wave systems, that can facilitate building such effective transport networks in many use cases. For each technology, we present the system concept, possible application cases, and some demonstration results. We also discuss potential standardization and development directions so that the proposed technologies can be widely used.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • High-speed Optical and Millimeter-wave Wireless Link for Disaster Recovery

    Ken-ichi Kitayama, Yuki Yoshida, Yuya Yamaguchi, Hirochika Nakajima, Kosuke Nishimura, Abdelmoula Bekkali, Masayuki Oishi, Naoyasu Kamiya, Keiji Tanaka, Hidenori Iwai, Kazuya Ota, Norihiko Sato, Yoichi Oikawa, Kazukiyo Joshin, Nobuhiko Shibagaki, Kaoru Higuma, Satoshi Oikawa, Junichiro Ichikawa, Atsushi Kanno, Tetsuya Kawanishi

    2015 IEEE GLOBECOM WORKSHOPS (GC WKSHPS)     1 - 6  2015  [Refereed]

     View Summary

    A government-funded R&D program aiming at a resilient optical and millimeter-wave wireless link for a novel span protection scheme in a disaster recovery is presented. We also describe the key enabling technologies of both optical and wireless sub-systems and devices, including MIMO radio-over-fiber system, optical two-tone generation, and the transceiver and power amplifier in W-band.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Simultaneous multichannel wavelength multicasting and XOR logic gate multicasting for three DPSK signals based on four-wave mixing in quantum-dot semiconductor optical amplifier

    Jun Qin, Guo-Wei Lu, Takahide Sakamoto, Kouichi Akahane, Naokatsu Yamamoto, Danshi Wang, Cheng Wang, Hongxiang Wang, Min Zhang, Tetsuya Kawanishi, Yuefeng Ji

    OPTICS EXPRESS   22 ( 24 ) 29413 - 29423  2014.12  [International journal]

     View Summary

    In this paper, we experimentally demonstrate simultaneous multichannel wavelength multicasting (MWM) and exclusive-OR logic gate multicasting (XOR-LGM) for three 10Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signals in quantum-dot semiconductor optical amplifier (QD-SOA) by exploiting the four-wave mixing (FWM) process. No additional pump is needed in the scheme. Through the interaction of the input three 10Gbps DPSK signal lights in QD-SOA, each channel is successfully multicasted to three wavelengths (1-to-3 for each), totally 3-to-9 MWM, and at the same time, three-output XOR-LGM is obtained at three different wavelengths. All the new generated channels are with a power penalty less than 1.2dB at a BER of 10(-9). Degenerate and non-degenerate FWM components are fully used in the experiment for data and logic multicasting. (C) 2014 Optical Society of America

    DOI PubMed

  • High-capacity self-homodyne PDM-WDM-SDM transmission in a 19-core fiber

    Benjamin J. Puttnam, Ruben Luis, Jose-Manuel Delgado-Mendinueta, Jun Sakaguchi, Werner Klaus, Yoshinari Awaji, Naoya Wada, Atsushi Kanno, Tetsuya Kawanishi

    OPTICS EXPRESS   22 ( 18 ) 21185 - 21191  2014.09  [Refereed]  [International journal]

     View Summary

    We investigate a high-capacity, space-division-multiplexed (SDM) transmission system using self-homodyne detection (SHD) in multicore fiber (MCF). We first investigate SHD phase noise cancellation with both kHz and MHz range linewidths for both quadrature-phase shift-keyed (QPSK) and 16 quadrature-amplitude modulation (16QAM) signals, finding that phase noise cancellation in SHD enabled transmission with MHz linewidth lasers that resulted in error floors when using intradyne detection. We then demonstrate a high throughput SHD transmission system using low-cost, MHz linewidth distributed feedback lasers. We transmit a CW pilot-tone on a single core of a 10.1 km MCF span with the remaining 18 cores used to transmit 125 wavelength-division multiplexed (WDM) QPSK and polarization-division-multiplexed (PDM)-QPSK signals with 50 GHz channel spacing at 25 GBd. For PDM transmission and assuming a 7% forward-error correction overhead this is equivalent 210 Tb/s transmission with a SE of 33.4 b/s/Hz. High-capacity transmission is achieved despite high inter-core crosstalk, broad transmitter linewidth and narrow channel spacing, showing that combining SHD with MCF enables high throughput, low-cost transmission in next-generation optical networks. (C) 2014 Optical Society of America

    DOI PubMed

  • High extinction ratio characteristics of over 60 dB Mach-Zehnder modulator with asymmetric power-splitting Y-branches on X-cut Ti:LiNbO3

    Yuya Yamaguchi, Shinya Nakajima, Atsushi Kanno, Tetsuya Kawanishi, Masayuki Izutsu, Hirochika Nakajima

    JAPANESE JOURNAL OF APPLIED PHYSICS   53 ( 8 )  2014.07  [Refereed]

     View Summary

    We discuss the performance of Mach-Zehnder modulators with asymmetric power-splitting Y-branches theoretically and confirmed it experimentally. The output characteristics of the modulator depend on the relationship between the power splitting ratios of the front and the back Y-branches. Even if the modulator consists of two asymmetric Y-branches, we can achieve high-extinction-ratio operation, with an additional loss as compared with the ideal case, by tuning the splitting ratio of only one of the two Y-branches. The additional loss, however, is small in many cases because the asymmetry considered here is caused by fabrication errors. (C) 2014 The Japan Society of Applied Physics

    DOI

    Scopus

    20
    Citation
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  • Pump-linewidth-tolerant optical wavelength conversion for high-order QAM signals using coherent pumps

    Guo-Wei Lu, Andre Albuquerque, Benjamin J. Puttnam, Takahide Sakamoto, Miguel Drummond, Rogerio Nogueira, Atsushi Kanno, Satoshi Shinada, Naoya Wada, Tetsuya Kawanishi

    OPTICS EXPRESS   22 ( 5 ) 5067 - 5075  2014.03  [Refereed]  [International journal]

     View Summary

    Optical wavelength conversion (OWC) is expected to be a desirable function in future optical transparent networks. Since high-order quadrature amplitude modulation (QAM) is more sensitive to the phase noise, in the OWC of high-order QAM signals, it is crucial to suppress the extra noise introduced in the OWC subsystem, especially for the scenario with multiple cascaded OWCs. Here, we propose and experimentally demonstrate a pump-linewidth-tolerant OWC scheme suitable for high-order QAM signals using coherent two-tone pumps. Using 3.5-MHz-linewidth distributed feedback (DFB) lasers as pump sources, our scheme enables wavelength conversion of both 16QAM and 64QAM signals with negligible power penalty, in a periodically-poled Lithium Niobate (PPLN) waveguide based OWC. We also demonstrate the performance of pump phase noise cancellation, showing that such coherent two-tone pump schemes can eliminate the need for ultra-narrow linewidth pump lasers and enable practical implementation of low-cost OWC in future dynamic optical networks. (C)2014 Optical Society of America

    DOI PubMed

  • C-3-21 Improvement of the Suppression of the Optical Harmonic by Optical SSB-SC Modulation with Third-order Harmonic

    NAKAO Ryota, YAMAGUCHI Yuya, KANNO Atsushi, KAWANISHI Tetsuya, IZUTSU Masayuki, NAKAJIMA Hirochika

    Proceedings of the IEICE General Conference   2014 ( 1 ) 176 - 176  2014.03

    CiNii

  • C-3-20 Low Driving Voltage LiNbO_3 Optical Modulator using Phase Matching by Folded Structure

    IIMURA Tetsuhito, NAKAJIMA Shinya, KANNO Atsushi, KAWANISHI Tetsuya, NAKAJIMA Hirochika, IZUTSU Masayuki

    Proceedings of the IEICE General Conference   2014 ( 1 ) 175 - 175  2014.03

    CiNii

  • Error-Free and Laser-Phase-Noise-Insensitive Optical Coherent Transmission of Uplink Radio-over-Fiber signal

    Toshiaki Kuri, Takahide Sakamoto, Guo-Wei Lu, Tetsuya Kawanishi

    2014 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2014

     View Summary

    Laser-phase-noise-insensitive optical coherent transmission of a radio-over-fiber signal with two-tone local light and digital signal processing technique is experimentally demonstrated. The estimated BER of less than 10(-9) is successfully achieved after 20-km-long fiber-optic transmission.

    DOI

  • Coherently-Pumped FWM in HNLF for 16QAM Wavelength Conversion Free of Phase Noise from Pumps

    Guo-Wei Lu, Takahide Sakamoto, Tetsuya Kawanishi

    2014 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)     1 - 3  2014  [Refereed]

     View Summary

    We experimentally demonstrate a 50-Gbps 16QAM wavelength conversion with &lt;0.2dB penalty, based on FWM in HNLF using coherent pumps. The coherent pumping makes it independent of the phase noise from pumps and enables the use of cost-effective pump laser.

    DOI

  • Direct Chirp Measurement of Electro Absorption Modulator Using Optical Homodyne Quadrature Demodulation Technique

    Ukrit Mankong, Tanawat Tangmala, Keizo Inagaki, Atsushi Kanno, Tetsuya Kawanishi

    2014 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)     1 - 3  2014  [Refereed]

     View Summary

    We propose a novel method to measure chirp of an electro-absorption modulator at any frequency using optical homodyne quadrature demodulation technique. Chirp parameters are directly obtained in the small-signal vector space, enabling practical chirp assessment for advanced modulation optical transmission.

    DOI

  • Optical DFG-based 60 GHz signal generation by using a LiTaO3 rectangular waveguide

    Yusuke Takashima, Yuto Maejima, Hiroshi Murata, Yasuyuki Okamura, Atsushi Kanno, Tetsuya Kawanishi

    IEICE ELECTRONICS EXPRESS   11 ( 12 ) 20140381 - 20140381  2014  [Refereed]

     View Summary

    Millimeter-wave (MMW) signal generation devices using difference frequency generation (DFG) based on the second order nonlinear optical effect in a rectangular waveguide were studied in detail theoretically and experimentally. The temporal and spatial coupling process of a generated MMW signal to a TE10 mode in a rectangular waveguide embedded with a nonlinear crystal was analyzed using the finite-difference time-domain (FDTD) method. In the experiment, 60 GHz-band signals were successfully obtained from fabricated prototype devices using a rectangular waveguide embedded with z-cut LiTaO3 crystal.

    DOI

  • Radio-on-Terahertz Over Fiber System for Future Mobile Fronthauling

    Atsushi Kanno, Pham Tien Dat, Iwao Hosako, Tetsuya Kawanishi, Hiroyo Ogawa

    2014 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM 2014)     2218 - 2222  2014  [Refereed]

     View Summary

    The technology of encapsulating a microwave signal into a terahertz carrier and an optical signal is proposed and demonstrated experimentally. Broad bandwidth terahertz radio can encapsulate existing microwave services, including advanced mobile communication signals, by using photonics technology. The concept of radio-on-terahertz-over-fiber helps to realize the future design of mobile fronthaul links. These links will have seamless connectivity between radio and optical networks because of the low latency of the links, which results from the use of analog signal transmission technology.

    DOI

  • Ultra high-speed fiber wireless transport

    Tetsuya Kawanishi

    2014 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2014  [Refereed]

     View Summary

    This paper describes high-speed data transmission based on combination of optical fiber and radio-wave links, which would enable low-latency transfer and agile deployment capability, where broadband radio signal waveforms can be transferred by radio-on-fiber technology.

    DOI

  • Seamless W-Band Radio-to-Optical Signal Conversion with Direct IQ Down-Converter

    Atsushi Kanno, Pham Tien Dat, Toshiaki Kuri, Iwao Hosako, Tetsuya Kawanishi, Yuki Yoshida, Ken-ichi Kitayama

    2014 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2014  [Refereed]

     View Summary

    Seamless conversion from millimeter-wave radio signals to optical baseband signals was demonstrated using a direct IQ down-converter. Hybrid optical and millimeter-wave signal transmission was performed using a conventional digital-coherent receiver, without any special algorithms. (C) 2013 Optical Society of America

    DOI

  • Wavelength conversion of optical 64QAM through FWM in HNLF and its performance optimization by constellation monitoring

    Guo-Wei Lu, Takahide Sakamoto, Tetsuya Kawanishi

    OPTICS EXPRESS   22 ( 1 ) 15 - 22  2014.01  [Refereed]  [International journal]

     View Summary

    All-optical wavelength conversion (AOWC) plays an important role in the future transparent optical networks, in order to enhance the reconfigurability and non-blocking capacity. On the other hand, high-order quadrature amplitude modulations (QAMs) have been extensively studied for achieving the high-speed and high-spectral-efficiency optical transmission. Since high-order QAMs are more sensitive to phase and amplitude noise, to implement an AOWC sub-system suitable for highorder QAM signals with minimized power penalty, it is important to optimize the operation conditions in order to avoid extra nonlinear distortions co-existed in the AOWC process. Our experimental results show that, constellation monitoring provides a more intuitive and accurate approach to monitor the converted high-order QAM signals, especially in presence of nonlinear phase noise such as self-phase modulation (SPM). We experimentally demonstrate an AOWC of 64QAM signal through fourwave mixing (FWM) in highly-nonlinear (HNLF). The performance of the AOWC is optimized through the constellation monitoring of the converted signal, achieving a negligible power penalty (&lt; 0.3dB at BER of 10-3) for 60-Gbps 64QAM after conversion. (C) 2013 Optical Society of America

    DOI PubMed

  • Evaluation of Frequency Fluctuation in Fiber-Wireless Link with Direct IQ Down-Converter

    Atsushi Kanno, Pham Tien Dat, Toshiaki Kuri, Iwao Hosako, Tetsuya Kawanishi, Yuki Yoshida, Ken'ichi Kitayama

    2014 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)     1 - 3  2014  [Refereed]

     View Summary

    We demonstrate 12-Gbaud QPSK signal transmission in a fiber-wireless link and compare a modulator-based optical two-tone generator and an optical heterodyning with free-running lasers. The obtained frequency fluctuation of the two-tone system meets the requirements of the radio regulations.

    DOI

  • Time-Interleaved Carrier-Suppressed Return-to-Zero QPSK for Filter-less Dual-Carrier Transmission

    Takahide Sakamoto, Guo-Wei Lu, Tetsuya Kawanishi

    2014 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)     1 - 3  2014  [Refereed]

     View Summary

    We demonstrate time-interleaved carrier-suppressed return-to-zero (TI-CSRZ) signaling, aiming for high-spectral-efficiency dual-carrier transmission. Optical filter-less modulation and demodulation schemes are proposed, achieving 40-Gb/s TI-CSRZ-QPSK.

    DOI

  • Extinction-Ratio and Chirp Tunable LiNbO3 Single-Drive Modulator for Precise Amplitude Modulation

    Yuya Yamaguchi, Shinya Nakajima, Atsushi Kanno, Tetsuya Kawanishi, Masayuki Izutsu, Hirochika Nakajima

    2014 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)     1 - 3  2014  [Refereed]

     View Summary

    We propose an extinction-ratio and chirp tunable modulator in single-drive operation. Using the modulator, we demonstrated precise amplitude modulation without parasitic phase modulation. Extinction-ratio was larger than 52.2 dB, with low chirp (&lt;vertical bar 0.007 vertical bar) operation.

    DOI

  • Pump-Linewidth-Tolerant Optical Data Exchange between 16QAM and QPSK with 50-GHz Channel-Spacing using Coherent DFB Pump

    Guo-Wei Lu, Andre Albuquerque, Benjamin J. Puttnam, Takahide Sakamoto, Miguel Drummond, Rogerio Nogueira, Atsushi Kanno, Satoshi Shinada, Naoya Wada, Tetsuya Kawanishi

    2014 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)     1 - 3  2014  [Refereed]

     View Summary

    We propose and experimentally demonstrate optical data exchange scheme between 16QAM and QPSK with narrow spacing of 50GHz. The use of coherent pump makes it free of phase noise from pumps, and enables the use of low-cost DFB as pump source.

    DOI

  • DIGITAL SIGNAL PROCESSING TECHNIQUES FOR MULTI-CORE FIBER TRANSMISSION USING SELF-HOMODYNE DETECTION SCHEMES

    Jose Manuel Delgado Mendinueta, Ruben S. Luis, Benjamin J. Puttnam, Jun Sakaguchi, Werner Klaus, Yoshinari Awaji, Naoya Wada, Atsushi Kanno, Tetsuya Kawanishi

    2014 PROCEEDINGS OF THE 22ND EUROPEAN SIGNAL PROCESSING CONFERENCE (EUSIPCO)     1880 - 1884  2014  [Refereed]  [Invited]

     View Summary

    We discuss digital signal processing (DSP) techniques for self-homodyne detection (SHD), multi-core fiber (MCF) transmission links, and related technologies. We focus on exploiting the reduced phase noise of self-homodyne multi-core fiber (SH-MCF) systems to enable DSP resource savings and describe digital receiver architectures that mixes signal and local oscillator in the digital domain.

  • Quantum dot two-mode laser at 1.55 mu m-band for 90GHz radio over fiber applications

    Kouichi Akahane, Naokatsu Yamamoto, Atsushi Kanno, Toshimasa Umezawa, Tetsuya Kawanishi

    2014 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)     1 - 3  2014  [Refereed]

     View Summary

    The two-mode lasing is obtained at the telecom-band using an InAs quantum dot gain chip. The wavelengths of the two modes were 1539.73 and 1540.44 nm corresponded to the frequency separation of 89.8 GHz which generated millimeter wave signal.

    DOI

  • Electro-Optic Devices for Imaging Systems Using Radio-over-Fibre

    Tetsuya Kawanishi, Naokatsu Yamamoto, Toshimasa Umezawa, Kouichi Akahane, Atsushi Kanno, Pham Tien Dat

    2014 16TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON)     1 - 4  2014  [Refereed]

     View Summary

    This paper describes high-speed optical modulation and detection devices for radio-over-fibre ( RoF) systems which can distribute millimetre-wave signals over optical fibres with low-loss, and RoF-based high-performance imaging systems which can be used for foreign object debris in runways or railways. High-speed and high-sensitivity photo-detection would be very important to achieve high-resolution imaging. We will share our recent research results on precise lightwave modulation techniques and on high-speed photodetectors using quantum dots.

    DOI

  • Evaluation of high-frequency region crosstalk in interferometric-type optical switch and its suppression using optical-intensity trimmer structures

    CHIBA Akito, KAWANISHI Tetsuya, SAKAMOTO Takahide, HIGUMA Kaoru, TAKADA Kazumasa, IZUTSU Masayuki

    Technical report of IEICE. LQE   113 ( 395 ) 321 - 324  2014.01

     View Summary

    We propose evaluation procedure of crosstalk in Balanced-Bridge Interferometric (BBI) type optical switch driven by rf signal. This proposal utilizes degree of carrier-component optical power at drop port. One of the features is that this evaluation would not be restricted within finite gain-bandwidth product of an optical detector adopted at time-domain measurement. Using this proposal, crosstalk of a BBI-type 2x2 switch possessing two Mach-Zehnder structures is also evaluated.

    CiNii

  • Evaluation of high-frequency region crosstalk in interferometric-type optical switch and its suppression using optical-intensity trimmer structures

    CHIBA Akito, KAWANISHI Tetsuya, SAKAMOTO Takahide, HIGUMA Kaoru, TAKADA Kazumasa, IZUTSU Masayuki

    Technical report of IEICE. OPE   113 ( 394 ) 321 - 324  2014.01

     View Summary

    We propose evaluation procedure of crosstalk in Balanced-Bridge Interferometric (BBI) type optical switch driven by rf signal. This proposal utilizes degree of carrier-component optical power at drop port. One of the features is that this evaluation would not be restricted within finite gain-bandwidth product of an optical detector adopted at time-domain measurement. Using this proposal, crosstalk of a BBI-type 2x2 switch possessing two Mach-Zehnder structures is also evaluated.

    CiNii

  • Evaluation of high-frequency region crosstalk in interferometric-type optical switch and its suppression using optical-intensity trimmer structures

    CHIBA Akito, KAWANISHI Tetsuya, SAKAMOTO Takahide, HIGUMA Kaoru, TAKADA Kazumasa, IZUTSU Masayuki

      113 ( 396 ) 321 - 324  2014.01

     View Summary

    We propose evaluation procedure of crosstalk in Balanced-Bridge Interferometric (BBI) type optical switch driven by rf signal. This proposal utilizes degree of carrier-component optical power at drop port. One of the features is that this evaluation would not be restricted within finite gain-bandwidth product of an optical detector adopted at time-domain measurement. Using this proposal, crosstalk of a BBI-type 2x2 switch possessing two Mach-Zehnder structures is also evaluated.

    CiNii

  • Evaluation of high-frequency region crosstalk in interferometric-type optical switch and its suppression using optical-intensity trimmer structures

    CHIBA Akito, KAWANISHI Tetsuya, SAKAMOTO Takahide, HIGUMA Kaoru, TAKADA Kazumasa, IZUTSU Masayuki

      113 ( 397 ) 321 - 324  2014.01

     View Summary

    We propose evaluation procedure of crosstalk in Balanced-Bridge Interferometric (BBI) type optical switch driven by rf signal. This proposal utilizes degree of carrier-component optical power at drop port. One of the features is that this evaluation would not be restricted within finite gain-bandwidth product of an optical detector adopted at time-domain measurement. Using this proposal, crosstalk of a BBI-type 2x2 switch possessing two Mach-Zehnder structures is also evaluated.

    CiNii

  • Evaluation of high-frequency region crosstalk in interferometric-type optical switch and its suppression using optical-intensity trimmer structures

    CHIBA Akito, KAWANISHI Tetsuya, SAKAMOTO Takahide, HIGUMA Kaoru, TAKADA Kazumasa, IZUTSU Masayuki

      113 ( 393 ) 321 - 324  2014.01

     View Summary

    We propose evaluation procedure of crosstalk in Balanced-Bridge Interferometric (BBI) type optical switch driven by rf signal. This proposal utilizes degree of carrier-component optical power at drop port. One of the features is that this evaluation would not be restricted within finite gain-bandwidth product of an optical detector adopted at time-domain measurement. Using this proposal, crosstalk of a BBI-type 2x2 switch possessing two Mach-Zehnder structures is also evaluated.

    CiNii

  • Multi-tone parallel coherent matched detection for demultiplexing of superchannels

    Takahide Sakamoto, Guo-Wei Lu, Tetsuya Kawanishi

    OPTICS EXPRESS   21 ( 16 ) 18602 - 18610  2013.08  [Refereed]  [International journal]

     View Summary

    This paper presents multi-tone parallel coherent matched detection that orthogonally detects superchannels without crosstalk between neighboring channels. The receiver consists of multiple sets of multi-tone coherent matched detector employed in parallel. In each detector, the received superchannels signal is homodyne mixed in multi frequency with locally generated multi-tone optical frequency comb; detected is a signal set that has the amplitude and phase exactly matched with the local comb. By launching orthogonal sets of local comb to the multiple parallel coherent matched detectors, the received superchannels are orthogonally downconverted to the baseband frequencies keeping the amplitude and phase information of all channels included. With an aid of n x n transform matrix, all channels are separately recovered from the downconverted signal sets. The system does not rely on any optical filters for channel demultiplexing and separation, with increased flexibility in wavelength arrangement. In addition, the parallel configuration equivalently enhance the bandwidth of the coherent matched detector keeping the speed in each tributary channel as high as possible. In this paper, it is experimentally demonstrated that even-odd interleaved 23 x 20-Gb/s QPSK superchannels are orthogonally demultiplexed and detected by two-tone coherent matched detection. (c) 2013 Optical Society of America

    DOI PubMed

  • Flexible high-order QAM transmitter using tandem IQ modulators for generating 16/32/36/64-QAM with balanced complexity in electronics and optics

    Guo-Wei Lu, Takahide Sakamoto, Tetsuya Kawanishi

    OPTICS EXPRESS   21 ( 5 ) 6213 - 6223  2013.03  [Refereed]  [International journal]

     View Summary

    In order to adapt to the dynamics in the future optical networks, we propose a flexible high-order QAM transmitter using a tandem in-phase/quadrature (IQ) modulators to synthesize different high-order quadrature amplitude modulation (QAM) formats, such as 16QAM, 32 or 36QAM and 64QAM. To generate high-order QAMs, an offset-QAM is firstly generated using an IQ modulator driven by electronics with reduced modulation-level, and then mapped to other quadrants through another following IQ modulator configured as a standard quadrature phase-shift keying (QPSK) modulator. All of the embedded sub-Mach-Zehnder modulators are operated in push-pull configurations to avoid introducing excess phase chirp. In contrast with the schemes based on a single IQ modulator driven by multilevel electronics or a highly-integrated parallel modulator, by deploying commercially-available optical modulators and driving electronics with reduced modulation-level, the transmitter complexity in optics and electronics is well-balanced. In the case of generating optical 64QAM, different from another tandem scheme deploying dual-drive IQ modulator driven by independent four binary streams, less phase chirp is observed in our proposed scheme, and comparable implementation penalty is obtained even without applying additional specific compensation algorithm in the coherent receiver. Moreover, thanks to the tandem structure and the deployment of QPSK modulator, the obtained high-order QAM is naturally differentially coded, which is helpful to solve the phase ambiguity at coherent receiver. We experimentally demonstrate the generations of these high-order QAMs including 16QAM, 32/36QAM and 64QAM, and confirm the error-free operations with comparable BER performance to the "electrical" approach based on a single IQ modulator. (c) 2013 Optical Society of America

    DOI PubMed

  • 105Tb/s Transmission System Using Low-cost, MHz Linewidth DFB Lasers Enabled by Self-Homodyne Coherent Detection and a 19-Core Fiber

    Benjamin J. Puttnam, José-Manuel Delgado Mendinueta, Jun Sakaguchi, Ruben S. Luís, Werner Klaus, Yoshinari Awaji, Naoya Wada, Atsushi Kanno, Tetsuya Kawanishi

    2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC)     OW1I.1 - 3  2013.03  [Refereed]

    DOI

  • C-3-37 Bias control for high eXtinction ratio LN modulator with backward light

    Tanaka Masaki, Kanno Atsushi, Kawanishi etsuya, Izutsui Masayuki, Nakajima Hirochika

    Proceedings of the IEICE General Conference   2013 ( 1 ) 197 - 197  2013.03

    CiNii

  • C-3-36 Precision measurement ofchirp parameter of modulators for optical frequency comb generation

    yamada Yuki, Yamaguchi Yuya, Izutsu Masayuki, Kanno Atsushi, Kawanishi Tetsuya, Nakajima Hirochika

    Proceedings of the IEICE General Conference   2013 ( 1 ) 196 - 196  2013.03

    CiNii

  • Generation of Millimeter Waves with Fine Frequency Tunability Using Mach-Zehnder-Modulator-Based Flat Comb Generator

    Morohashi Isao, Irimajiri Yoshihisa, Sakamoto Takahide, Kawanishi Tetsuya, Yasui Motoaki, Hosako Iwao

    IEICE TRANSACTIONS ON ELECTRONICS   E96C ( 2 ) 192 - 196  2013.02  [Refereed]

    DOI

  • 10-GHz High-Repetition Optical Short Pulse Generation from Wavelength-Tunable Quantum Dot Optical Frequency Comb Laser

    Yamamoto Naokatsu, Akahane Kouichi, Kawanishi Tetsuya, Sotobayashi Hideyuki, Yoshioka Yuki, Takai Hiroshi

    IEICE TRANSACTIONS ON ELECTRONICS   E96C ( 2 ) 187 - 191  2013.02  [Refereed]

    DOI

  • Investigating self-homodyne coherent detection in a 19 channel space-division- multiplexed transmission link

    Benjamin J, Puttnam, Jun Sakaguchi, José-Manuel Delgado Mendinueta, Werner Klaus, Yoshinari Awaji, Naoya Wada, Atsushi Kanno, Tetsuya Kawanishi

    Optics Express   21 ( 2 ) 1561 - 1566  2013.01  [Refereed]  [International journal]

     View Summary

    We investigate the performance of a self-homodyne coherent detection (SHCD) system using a 19 core multi-core fiber (MCF) and 16 wavelength-division-multiplexed channels. We show that SHCD, with the pilot-tone transmitted on a single MCF core and information carrying signals on the remaining cores, is compatible with space-division-multiplexed transmission, potentially relaxing laser linewidth and digital signal processing requirements due to phase noise cancellation. However, inter-core crosstalk can have an impact on performance and core selection.

    DOI PubMed

  • PS-QPSK with duobinary-shaping and MLSD reception for constructing power- and spectrum-efficient superchannel.

    Guo-Wei Lu, Yukiyoshi Kamio, Tetsuya Kawanishi

    2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC)(OFC/NFOEC)     1 - 3  2013

  • Coherent optical and radio seamless transmission based on DSP-aided radio-over-fiber technology.

    Atsushi Kanno, Toshiaki Kuri, Iwao Hosako, Tetsuya Kawanishi, Yuki Yoshida, Yoshihiro Yasumura, Ken-ichi Kitayama

    2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC)(OFC/NFOEC)     1 - 3  2013

  • Standardization Activities for Radio on Fiber Transmitter within IEC TC103/WG5.

    Satoru Kurokawa, Junichiro Ichikawa, Tetsuya Kawanishi, Hiroyo Ogawa

    IEICE Transactions on Electronics   96-C ( 2 ) 138 - 146  2013

    DOI

  • Quadrature-phase-shift-keying radio-over-fiber transmission for coherent optical and radio seamless networks

    Atsushi Kanno, Pham Tien Dat, Toshiaki Kuri, Iwao Hosako, Tetsuya Kawanishi, Yoshihiro Yasumura, Yuki Yoshida, Ken-Ichi Kitayama

    IEICE Transactions on Electronics   E96-C ( 2 ) 156 - 162  2013  [Refereed]

     View Summary

    We propose a coherent optical and radio seamless network concept that allows broadband access without deployment of additional optical fibers within an optical fiber dead zone while enhancing network resilience to disasters. Recently developed radio-over-fiber (RoF) and digital coherent detection technologies can seamlessly convert between optical and radio signals. A millimeter-wave radio with a capacity greater than 10 Gb/s and high-speed digital signal processing is feasible for this purpose. We provide a preliminary demonstration of a high-speed, W-band (75-110 GHz) radio that is seamlessly connected to an optical RoF transmitter using a highly accurate optical modulation technique to stabilize the center frequencies of radio signals. Using a W-band digital receiver with a sensitivity of -37 dBm, we successfully transmitted an 18.6Gb/s quadrature-phase-shift-keying signal through both air and an optical fiber. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.

    DOI

  • Optical 64QAM Transmitter using Tandem IQ Modulators with Balanced Complexity in Electronics and Optics

    Guo-Wei Lu, Takahide Sakamoto, Tetsuya Kawanishi

    2013 OPTICAL FIBER COMMUNICATION CONFERENCE AND EXPOSITION AND THE NATIONAL FIBER OPTIC ENGINEERS CONFERENCE (OFC/NFOEC)     1 - 3  2013

     View Summary

    Instead of using eight-level electronics or highly-integrated optics, 64QAM generation is experimentally demonstrated using two tandem IQ modulators with four-level electronics. The complexity in electronics and optics is well-balanced. 16QAM and 36QAM are also synthesized.

  • Radio-over-fiber photonic wireless bridge in the W-Band

    Sebastian Babiel, Andreas Stohr, Atsushi Kanno, Tetsuya Kawanishi

    2013 IEEE International Conference on Communications Workshops, ICC 2013     838 - 842  2013  [Refereed]

     View Summary

    In this paper, we present a photonic wireless system operating in the W-Band (75-110 GHz) featuring ultra-high bandwidth as well as simple NRZ-OOK modulation format. By using a cascaded optical RF and data modulation approach on the transmitter side, flexible adjustment of the wireless RF carrier in the W-Band is achieved, while direct electrical to optical conversion with advanced photonic components on the receiver side enables true photonic wireless bridging. In first experiments, data rates up to 10 Gb/s have been experimentally demonstrated. © 2013 IEEE.

    DOI

  • Phase noise measurement of optical heterodyning two-tone signal generated by two free-running lasers

    Ryuta Yamanaka, Taka Fujita, Hideyuki Sotobayashi, Atsushi Kanno, Tetsuya Kawanishi

    IEICE Transactions on Electronics   E96-C ( 2 ) 241 - 244  2013  [Refereed]

     View Summary

    We evaluated the single side-band phase noise of a 40 GHz beat signal generated by two free-running lasers. This allowed us to verify the utility of the two free-running lasers is verified as a light source for a next-generation radio-over-fiber system using frequency such as those in the millimeter-wave and terahertz bands. We also measured the phase noise of a frequency quadrupler using a Mach-Zehnder modulator for comparison. The phase noise of the two free-running lasers and the frequency quadrupler are - 63.85 and -95.22 dBc/Hz at a 10 kHz offset frequency, respectively. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.

    DOI

  • Performance Evaluation of LTE Signal Transmission Over a Seamlessly Integrated Radio-Over-Fiber and Millimeter-Wave Wireless Link

    Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    2013 IEEE GLOBECOM WORKSHOPS (GC WKSHPS)     748 - 753  2013  [Refereed]

     View Summary

    Transmission of 3GPP LTE signal over a seamlessly integrated radio-over-fiber and millimeter-wave wireless link is theoretically analyzed and experimentally demonstrated. We successfully transmitted and demodulated standard LTE eNB conformance test signals using QPSK, 16-QAM and 64-QAM modulation format for user data over the proposed system. The measured EVM is well under the required limit defined for the test signals, showing the potential to use the link as a high capacity backhauling system for high speed mobile networks using small cells and/or high carrier frequency at millimeter-wave.

    DOI

  • Large-capacity transmission over a 19-core fiber

    Jun Sakaguchi, Benjamin J. Puttnam, Werner Klaus, Jose Manuel Delgado Mendinueta, Yoshinari Awaji, Naoya Wada, Atsushi Kanno, Tetsuya Kawanishi

    2013 OPTICAL FIBER COMMUNICATION CONFERENCE AND EXPOSITION AND THE NATIONAL FIBER OPTIC ENGINEERS CONFERENCE (OFC/NFOEC)     1 - 3  2013  [Refereed]

     View Summary

    We discuss the recent progress of space division multiplexed transmission using a 19-core fiber. We find that high core-number multi-core fibers can both enable large transmission capacity and potentially reduce system costs and power consumption.

  • Filter-less Multi-Tone Coherent Orthogonal Detection for Multi-Channel Reception of Super-Channel/OFDM signals

    Takahide Sakamoto, Guo-Wei Lu, Tetsuya Kawanishi

    2013 OPTICAL FIBER COMMUNICATION CONFERENCE AND EXPOSITION AND THE NATIONAL FIBER OPTIC ENGINEERS CONFERENCE (OFC/NFOEC)     1 - 3  2013  [Refereed]

     View Summary

    Multi-tone coherent-matched detection is demonstrated for multi-channel reception of superchannel/OFDM signals without optical filters for channel selection. Assisted with MIMO equalization, interleaved 23x20Gb/s QPSK are orthogonally demultiplexed.

  • Precise lightwave modulation for digital and analogue optical communications

    Tetsuya Kawanishi

    2013 IEEE 6TH INTERNATIONAL CONFERENCE ON ADVANCED INFOCOMM TECHNOLOGY (ICAIT)     207 - 208  2013  [Refereed]

     View Summary

    This paper describes high-speed electro-optic device technologies for radio-on-fiber (RoF) systems. Digital and analog signals can be transmitted over a fiber, in RoF systems. Multi-level modulation plays important roles both in wired and wireless systems. Quadrature amplitude modulation signals can be synthesized by using parallel Mach-Zehnder modulators.

    DOI

  • Energy and Deployment Efficiency of a Millimeter-Wave Radio-on-Radio-over-Fiber System for Railways

    Pham Tien Dat, Atsushi Kanno, Tetsuya Kawanishi

    2013 OPTICAL FIBER COMMUNICATION CONFERENCE AND EXPOSITION AND THE NATIONAL FIBER OPTIC ENGINEERS CONFERENCE (OFC/NFOEC)     1 - 3  2013  [Refereed]

     View Summary

    We propose a radio access network for railways employing millimeter-wave Radio-onRadio- over-fiber and distributed antenna system, and evaluate its energy and deployment efficiency. We show a trade-off relation between the metrics and drive optimum system design.

  • Coherent MMW/Terahertz Signal Transmission with Frequency-Reconfigurable RoF Transmitter Based on an Optical Frequency Comb

    Atsushi Kanno, Toshiaki Kuri, Isao Morohashi, Iwao Hosako, Tetsuya Kawanishi, Yuki Yoshida, Ken-ichi Kitayama

    2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM)     2686 - 2691  2013  [Refereed]

     View Summary

    A frequency-reconfigurable radio-over-fiber transmitter is designed and demonstrated with an optical frequency comb source for millimeter-wave and terahertz signal transmission over a fiber-wireless hybrid link. Optical-to-radio and radio-to-optical converters with a high-speed photo mixer and frequency-heterodyne technique successfully perform coherent quadrature-phase-shift-keying signal generation and reception in the optical domain at 90 GHz and 300 GHz. A digital radio receiver also receives and demodulates the transmitted QPSK signal at 300 GHz with the same bit error rate behavior as in an optical link.

    DOI

  • Low-crosstalk balanced bridge interferometric-type optical switch for optical signal routing

    Akito Chiba, Tetsuya Kawanishi, Takahide Sakamoto, Kaoru Higuma, Kazumasa Takada, Masayuki Izutsu

    IEEE Journal on Selected Topics in Quantum Electronics   19 ( 6 )  2013

     View Summary

    Crosstalk is one of the significant measures of an optical cross-bar switch. In this paper, we describe a configuration for crosstalk suppression of a balanced-bridge interferometric type optical switch and its application to an optical-signal routing device. Since crosstalk of the optical switch originates from imbalance in the amplitude of a lightwave propagating within the arm of the interferometer, additional Mach-Zehnder structures were embedded for trimming the amplitude of the light. By adjusting the transmittance of the trimmers, crosstalk of less than -56 dB is achieved for dc voltage. Also, for high-frequency voltages, a crosstalk estimation procedure was developed, and crosstalk at 10-GHz sinusoidal voltage was evaluated to be -48 dB. Furthermore, based on the transient response measurement, its switching time was evaluated to be 26 ps. For a demonstration utilizing extremely low crosstalk and quick response, a guard-time-free optical signal routing experiment is also described. © 2013 IEEE.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Precise chirp parameter measurement of asymmetric Mach-Zehnder modulators with active Y-branch

    Yuya Yamaguchi, Yuki Yamada, Atsushi Kanno, Tetsuya Kawanishi, Masayuki Izutsu, Hirochika Nakajima

    IEICE ELECTRONICS EXPRESS   10 ( 12 ) 20130311 - 20130311  2013  [Refereed]

     View Summary

    For precise chirp parameter control, we investigated x-cut LiNbO3 single-drive asymmetric Mach-Zehnder modulators with extinction-ratio adjustable active Y-branch structures, which can enhance on-off extinction ratio. The chirp parameter of the modulated output was precisely measured by using high extinction ratio operation. Experimental results show that it is possible to fabricate modulators with desired chirp parameters.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Optical and millimeter-wave radio seamless MIMO transmission based on a radio over fiber technology

    Atsushi Kanno, Toshiaki Kuri, Iwao Hosako, Tetsuya Kawanishi, Yuki Yoshida, Yoshihiro Yasumura, Ken-ichi Kitayama

    OPTICS EXPRESS   20 ( 28 ) 29395 - 29403  2012.12  [Refereed]  [International journal]

     View Summary

    Multi-input multi-output (MIMO) transmission of two millimeter-wave radio signals seamlessly converted from polarization-division-multiplexed quadrature-phase-shift-keying optical signals is successfully demonstrated, where a radio access unit basically consisting of only optical-to-electrical converters and a radio receiver performs total signal equalization of both the optical and the radio paths and demodulation with digital signal processing (DSP). Orthogonally polarized optical components that are directly converted to two-channel radio components can be demultiplexed and demodulated with high-speed DSP as in optical digital coherent detection. 20-Gbaud optical and radio seamless MIMO transmission provides a total capacity of 74.4 Gb/s with a forward error correction overhead of 7%. (C) 2012 Optical Society of America

    DOI PubMed

  • C-3-52 Waveguide structure for high extinction ratio LiNbO_3 MZ modulator with Active Y-branch

    YAMAGUCHI Yuya, NAKAJIMA Shinya, KANNO Atsushi, KAWANISHI Tetsuya, NAKAJIMA Hirochika

    Proceedings of the Society Conference of IEICE   2012 ( 1 ) 169 - 169  2012.08

    CiNii

  • Polarization division multiplexed 4 x 10 Gbps simultaneous transmissions in 1.0-mu m waveband and C-waveband over a 14.4-km-long holey fiber using an ultra-broadband photonic transport system

    Yu Omigawa, Naokatsu Yamamoto, Atsushi Kanno, Tetsuya Kawanishi, Yasuaki Kurata, Hideyuki Sotobayashi

    OPTICS EXPRESS   20 ( 14 ) 14864 - 14870  2012.07  [Refereed]  [International journal]

     View Summary

    Polarization division multiplexing (PDM) and wavelength division multiplexing (WDM) are essential techniques for enhancing the capacity of photonic networks and facilitating the efficient use of optical frequency resources. 2 PDM x 2 WDM x 10 Gbps error-free simultaneous transmissions in the 1.0-mu m waveband and C-waveband are successfully demonstrated for the first time using an ultra-broadband photonic transport system over a 14.4-km-long holey fiber transmission line. (c) 2012 Optical Society of America

    DOI PubMed

  • Adaptable access system: Pursuit of ideal future access system architecture

    Toshiaki Kuri, Hiroaki Harai, Naoya Wada, Tetsuya Kawanishi, Mizuhiko Hosokawa

    IEEE Network   26 ( 2 ) 42 - 48  2012.03  [Refereed]

     View Summary

    In this article, we propose a concept of an "adaptable access system" as future access system architecture. First, current issues and trends in communications networks are shown from various points of view, to discuss essential items for a future access system. Next, to set the basic direction of research and development for physical network infrastructure, three visions in the design of future access system architectures are shown. Based on the three visions, three technological targets (key concepts) for realizing the adaptable access system, active single star, servicearea-variable minimum cellular, and access system virtualization, are derived. © 2012 IEEE.

    DOI

  • Optoelectronic frequency response measurement of photodiodes by using high-extinction ratio optical modulator

    Keizo Inagakia, Tetsuya Kawanishi, Masayuki Izutsu

    IEICE ELECTRONICS EXPRESS   9 ( 4 ) 220 - 226  2012.02  [Refereed]

     View Summary

    We propose a measurement method of photodetector frequency response. This technique is based on a heterodyne principle, where a high-extinction ratio Mach-Zehnder modulator is used to generate a two-tone lightwave as a stimulus signal up to millimeter-wave frequency bands. Our proposing method can provide a relatively short traceability chain to optical and electric power standards.

    DOI

  • Monolithic mode-locked erbium-doped LiNbO3 waveguide laser with dielectric multilayer mirror

    Yutaro Katano, Satoshi Shinada, Shinya Nakajima, Tetsuya Kawanishi, Hirochika Nakajima

    IEICE ELECTRONICS EXPRESS   9 ( 4 ) 245 - 249  2012.02  [Refereed]

     View Summary

    We fabricated a diode-pumped mode-locked Ti-diffused Er-doped LiNbO3 (Ti:Er:LN) laser with a SiO2/TiO2 dielectric multilayered mirror. The lasing threshold power was 70mW at 1484 nm, and the slope efficiency was 1.48%. Stable optical pulses with a width of 10.86 ps were measured by driving the phase modulator at 13.575 GHz.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Phase noise analysis of an optical frequency comb using single side-band suppressed carrier modulation in an amplified optical fiber loop

    Atsushi Kanno, Tetsuya Kawanishi

    IEICE ELECTRONICS EXPRESS   9 ( 18 ) 1473 - 1478  2012  [Refereed]

     View Summary

    Coherent optical two-tone generation using an optical frequency comb generator based on an amplified optical fiber loop is successfully demonstrated. The observed phase noises in the 100-GHz band are less than -80 dBc/Hz at 1 MHz. This method is suitable for high-speed radio communication based on advanced modulation techniques.

    DOI

  • Narrow-line-width 1.31-mu m wavelength tunable quantum dot laser using sandwiched sub-nano separator growth technique

    Yamamoto Naokatsu, Akahane Kouichi, Kawanishi Tetsuya, Omigawa Yu, Sotobayashi Hideyuki, Yoshioka Yuki, Takai Hiroshi

    OPTICS EXPRESS   19 ( 26 ) 636 - 644  2011.12  [Refereed]  [International journal]

     View Summary

    A wide wavelength tunable quantum dot (QD) external cavity laser operating in the 1.31-μm waveband with a narrow line-width is successfully demonstrated. A high-density, high-quality InAs/InGaAs QD optical gain medium for the 1.31-μm waveband was obtained using a sandwiched sub-nano separator growth technique. A wide wavelength tunability of 1.265-1.321 μm and a narrow line-width of 210 kHz were successfully achieved using a compact and robust external cavity system constructed with multiple optical band-pass and etalon filters for active optical mode selection. The laser also achieved an error-free 10-Gb/s photonic data transmission over an 11.4-km-long holey fiber.

    DOI PubMed

  • 40 Gb/s W-band (75-110 GHz) 16-QAM radio-over-fiber signal generation and its wireless transmission.

    Kanno A, Inagaki K, Morohashi I, Sakamoto T, Kuri T, Hosako I, Kawanishi T, Yoshida Y, Kitayama K

    Optics express   19 ( 26 ) B56 - 63  2011.12  [Refereed]  [International journal]

     View Summary

    The generation of a 40-Gb/s 16-QAM radio-over-fiber (RoF) signal and its demodulation of the wireless signal transmitted over free space of 30 mm in W-band (75-110 GHz) is demonstrated. The 16-QAM signal is generated by a coherent polarization synthesis method using a dual-polarization QPSK modulator. A combination of the simple RoF generation and the versatile digital receiver technique is suitable for the proposed coherent optical/wireless seamless network.

    DOI PubMed

  • Rectangular QPSK for generation of optical eight-ary phase-shift keying

    Guo-Wei Lu, Takahide Sakamoto, Tetsuya Kawanishi

    Optics Express   19 ( 19 ) 18479 - 18485  2011.09  [Refereed]  [International journal]

     View Summary

    Quadrature phase-shift keying (QPSK) is usually generated using an in-phase/quadrature (IQ) modulator in a balanced driving-condition, showing a square-shape constellation in complex plane. This conventional QPSK is referred to as square QPSK (S-QPSK) in this paper. On the other hand, when an IQ modulator is driven in an un-balanced manner with different amplitudes in in-phase (I) and quadrature (Q) branches, a rectangular QPSK (R-QPSK) could be synthesized. The concept of RQPSK is proposed for the first time and applied to optical eight-ary phaseshift keying (8PSK) transmitter. By cascading an S-QPSK and an R-QPSK, an optical 8PSK could be synthesized. The transmitter configuration is based on two cascaded IQ modulators, which also could be used to generate other advanced multi-level formats like quadrature amplitude modulation (QAM) when different driving and bias conditions are applied. Therefore, the proposed transmitter structure has potential to be deployed as a versatile transmitter for synthesis of several different multi-level modulation formats for the future dynamic optical networks. A 30-Gb/s optical 8PSK is experimentally demonstrated using the proposed solution. © 2011 Optical Society of America.

    DOI PubMed

  • Air-gap structure between integrated LiNbO3 optical modulators and micromachined Si substrates

    Takigawa Ryo, Higurashi Eiji, Suga Tadatomo, Kawanishi Tetsuya

    OPTICS EXPRESS   19 ( 17 ) 15739 - 15749  2011.08  [Refereed]  [International journal]

     View Summary

    The air-gap structure between integrated LiNbO(3) optical modulators and micromachined Si substrates is reported for high-speed optoelectronic systems. The calculated and experimental results show that the high permittivity of the Si substrate decreases the resonant modulation frequency to 10 GHz LiNbO(3) resonant-type optical modulator chips on the Si substrate. To prevent this substrate effect, an air-gap was formed between the LiNbO(3) modulator and the Si substrate. The ability to fabricate the air-gap structure was demonstrated using low-temperature flip-chip bonding (100 °C) and a Si micromachining process, and its performance was experimentally verified.

    DOI PubMed

  • 90 Gbaud NRZ-DP-DQPSK Modulation with Full-ETDM Technique Using High-Speed Optical IQ Modulator

    Atsushi Kanno, Takahide Sakamo, Akito Chiba, Masaaki Sudo, Kaoru Higuma, Junichiro Ichikawa, Tetsuya Kawanishi

    IEICE TRANSACTIONS ON ELECTRONICS   E94C ( 7 ) 1179 - 1186  2011.07  [Refereed]

     View Summary

    We demonstrate high baud-rate DQPSK modulation with full-ETDM technique using a novel high-speed optical IQ modulator consisting of a ridge-type optical waveguide structure on a thin LiNbO3 substrate. Our fabrication technique achieves a drastic extension of the modulator's bandwidth and a reduction of half-wave voltage. Demonstration of 90-Gbaud NRZ-DP-DQPSK signal generation with the modulator successfully achieved a bit rate of 360-Gb/s under full-ETDM configuration.

    DOI

  • Reconfigurable multilevel transmitter using monolithically integrated quad Mach-Zehnder IQ modulator for optical 16-QAM and 8-PSK generation

    Guo-Wei Lu, Takahide Sakamoto, Akito Chiba, Tetsuya Kawanishi, Tetsuya Miyazaki, Kaoru Higuma, Masaaki Sudo, Junichiro Ichikawa

    OPTICS EXPRESS   19 ( 6 ) 5596 - 5601  2011.03  [Refereed]  [International journal]

     View Summary

    We propose and demonstrate a reconfigurable multilevel transmitter using a monolithically-integrated quad Mach-Zehnder inphase/quadrature (QMZ-IQ) modulator with binary driving electronics. Different from previous parallel-integrated quadrature amplitude modulation (QAM) transmitter solutions, only one electrode is required to adjust the relative phase offset among embedded sub-Mach-Zehnder modulators in the proposed IQ superstructure. By feeding different RF driving electronics and operating the integrated modulator as different bias conditions, different advanced multilevel modulation formats, such as QAM and 8-ary phase-shift keying (8-PSK), could be synthesized. In this paper, a 40-Gb/s 16-QAM and a 30-Gb/s 8-PSK are generated using the proposed multilevel transmitter, respectively. Offline digital processing is employed for bit-error rates estimation and constellation reconstruction. (C)2011 Optical Society of America

    DOI PubMed

  • C-14-13 Continuous generation of Two-tone lightwave with active Y-branch LiNbO_3 modulator

    Tsuchiya Yuta, Ogiso Yoshihiro, Shinada Satoshi, Nakajima Shinya, Kawanishi Tetsuya, Nakajima Hirochika

    Proceedings of the IEICE General Conference   2011 ( 1 ) 294 - 294  2011.02

    CiNii

  • Beam steering array antenna controlled by optical wavelength.

    Keizo Inagaki, Takashi Ohira, Tetsuya Kawanishi, Masayuki Izutsu

    IEICE Electron. Express   8 ( 15 ) 1221 - 1227  2011

    DOI

  • Synthesis of 16 Quadrature Amplitude Modulation Using Polarization-Multiplexing QPSK Modulator

    MOROHASHI Isao, SAKAMOTO Takahide, SUDO Masaaki, KANNO Atsushi, CHIBA Akito, ICHIKAWA Junichiro, KAWANISHI Tetsuya

    IEICE Trans Commun (Inst Electron Inf Commun Eng)   E94-B ( 7 ) 1809 - 1814  2011

    DOI CiNii

  • 20-Gb/s QPSK W-band (75-110GHz) wireless link in free space using radio-over-fiber technique

    KANNO Atsushi, INAGAKI Keizo, MOROHASHI Isao, SAKAMOTO Takahide, KURI Toshiaki, HOSAKO Iwao, KAWANISHI Tetsuya, YOSHIDA Yuki, KITAYAMA Ken-ichi

    IEICE Electron Express (Web)   8 ( 8 ) 612 - 617  2011

    DOI CiNii

  • 100 Gb/s DQPSK field trial: Live video transmission over an operating LambdaXtreme® network

    Gregory Raybon, Peter J. Winzer, Haoyu Song, Andrew Adamiecki, Stephen Corteselli, Alan H. Gnauck, Thomas Kissell, Daniel A. Fishman, Nat M. Denkin, Yuan-Hua Kao, Terry L. Downs, Anthony Carenza, Stephan Scrudato, Edward H. Goode, William A. Thompson, Christopher R. Doerr, Lawrence L. Buhl, Tiejun Xia, Glenn Wellbrock, Wang Lee, Greg Lyons, Peter Hofmann, Tina T. Fisk, E. Bert Basch, William J. Kluge, Johnny R. Gatewood, Tetsuya Kawanishi, Kaoru Higuma, Yves Painchaud

    Bell Labs Technical Journal   14 ( 4 ) 85 - 114  2010.12  [Refereed]

     View Summary

    Successful transmission of live (real time) video traffic is demonstrated using a prototype 100 Gb/s single-polarization differential quadrature phase shift keying (DQPSK) transmitter and receiver over an in-service 504 km link of the LambdaXtreme® optical transport platform. Teaming with Verizon Business, we demonstrate the feasibility of upgrading an existing, live traffic bearing network to 100 Gb/s per wavelength without any changes to the current hardware or software. The 107 Gb/s signal is added at a reconfigurable optical add/drop multiplexer (ROADM) at a network node in Tampa, Florida, and dropped at a ROADM in Miami, Florida, where both live video and pseudorandom test sequences are received. In addition, we discuss the steps leading up to this field trial that included several important precursor laboratory experiments. We detail the generation, detection, coding, and longhaul transmission of single-polarization DQPSK at a line rate of 53.5 Gbaud to support a net information bit rate of 100 Gb/s. © 2010 Alcatel-Lucent.

    DOI

  • Ultrafast and broadband frequency chirp signal generation using a high-extinction-ratio optical modulator.

    Kanno A, Honda S, Yamanaka R, Sotobayashi H, Kawanishi T

    Optics letters   35 ( 24 ) 4160 - 2  2010.12  [Refereed]  [International journal]

     View Summary

    We successfully demonstrate ultrafast frequency sweep signal generation using the double-sideband suppressed carrier modulation technique with a high-extinction-ratio optical modulator that helps realize clear signals with no filters. The resultant sweep rate was achieved at 3.67 × 10(16) Hz/s with an extinction ratio above 25 dB, which corresponds to a bandwidth of 11 GHz with a pulse duration of 300 ns.

    DOI PubMed CiNii

  • 120-Gb/s NRZ-DQPSK signal generation by a thin-lithium-niobate-substrate modulator.

    Atsushi Kanno, Takahide Sakamoto, Akito Chiba, Tetsuya Kawanishi, Kaoru Higuma, Masaaki Sudou, Junichiro Ichikawa

    IEICE Electronic Express   7 ( 11 ) 817 - 822  2010.07  [Refereed]

    DOI

  • High efficiency and downsizing of a resonant type LiNbO_3 optical modulator with Au mirror

    TAKAHASHI Yuta, TSUCHIYA Yuta, SHINADA Satoshi, NAKAJIMA Shinya, KAWANISHI Tetsuya, NAKAJIMA Hirochika

    Technical report of IEICE. OPE   110 ( 156 ) 33 - 36  2010.07

     View Summary

    We aim to attempt high efficiency and downsizing of an LiNbO_3 optical modulator widely used in the optical communication system. We have proposed a resonant type optical modulator with an Au mirror. The resonant type optical modulator has a higher efficiency of optical modulation because the electric field on a modulating electrode can be enhanced by an electric resonance. The modulation efficiency and the modulator size have been improved further by reflecting a light wave with the Au mirror.

    CiNii

  • High efficiency and downsizing of a resonant type LiNbO_3 optical modulator with Au mirror

    TAKAHASHI Yuta, TSUCHIYA Yuta, SHINADA Satoshi, NAKAJIMA Shinya, KAWANISHI Tetsuya, NAKAJIMA Hirochika

    IEICE technical report. Microwaves   110 ( 155 ) 33 - 36  2010.07

     View Summary

    We aim to attempt high efficiency and downsizing of an LiNbO_3 optical modulator widely used in the optical communication system. We have proposed a resonant type optical modulator with an Au mirror. The resonant type optical modulator has a higher efficiency of optical modulation because the electric field on a modulating electrode can be enhanced by an electric resonance. The modulation efficiency and the modulator size have been improved further by reflecting a light wave with the Au mirror.

    CiNii

  • High efficiency and downsizing of a resonant type LiNbO_3 optical modulator with Au mirror

    TAKAHASHI Yuta, TSUCHIYA Yuta, SHINADA Satoshi, NAKAJIMA Shinya, KAWANISHI Tetsuya, NAKAJIMA Hirochika

      2010 ( 62 ) 33 - 36  2010.07

    CiNii

  • High Extinction-Ratio Integrated Mach-Zehnder Modulator With Active Y-Branch for Optical SSB Signal Generation

    Yoshihiro Ogiso, Yuta Tsuchiya, Satoshi Shinada, Shinya Nakajima, Tetsuya Kawanishi, Hirochika Nakajima

    IEEE PHOTONICS TECHNOLOGY LETTERS   22 ( 12 ) 941 - 943  2010.06  [Refereed]

     View Summary

    We propose a high extinction-ratio (ER) Mach-Zehnder modulator (MZM) with an active Y-branch optical intensity trimmer. In addition, we investigate a high ER integrated MZM for optical single-sideband (SSB) signal generation, where the active Y-branch trimmers are embedded in a dual-parallel MZM. Optical SSB generation with high suppression ratio of main carrier (47 dB) and undesired sidebands (&gt;42 dB) is achieved by optimizing the optical amplitude imbalances corresponding to the ER.

    DOI

    Scopus

    63
    Citation
    (Scopus)
  • Examination about bias control method of parallel LiNbO_3 optical modulators

    TSUCHIYA Yuta, SAKAMOTO Takahide, KAWANISHI Tetsuya, NAKAJIMA Hirochika

    Technical report of IEICE. LQE   110 ( 103 ) 31 - 35  2010.06

     View Summary

    We improved extinction ratio by putting a new electrode on a Y-branch structure at input side of a Mach-Zehnder interferometer. Allowing for applying this method to a multi-value modulation technology, we confirmed a bias control method of parallel LiNbO_3 modulators by simulation. Besides, due to the new electrode structure causes phase shift of lightwave, a new bias control compensating the influence of the phase shift is needed. In this paper, we confirmed the influence of the phase shift by experimentation. And for putting these methods to practical use and introducing to parallel LiNbO_3 optical modulators, we investigated a bias control method of the new electrode structure.

    CiNii

  • Examination about bias control method of parallel LiNbO_3 optical modulators

    TSUCHIYA Yuta, SAKAMOTO Takahide, KAWANISHI Tetsuya, NAKAJIMA Hirochika

    Technical report of IEICE. OPE   110 ( 102 ) 31 - 35  2010.06

     View Summary

    We improved extinction ratio by putting a new electrode on a Y-branch structure at input side of a Mach-Zehnder interferometer. Allowing for applying this method to a multi-value modulation technology, we confirmed a bias control method of parallel LiNbO_3 modulators by simulation. Besides, due to the new electrode structure causes phase shift of lightwave, a new bias control compensating the influence of the phase shift is needed. In this paper, we confirmed the influence of the phase shift by experimentation. And for putting these methods to practical use and introducing to parallel LiNbO_3 optical modulators, we investigated a bias control method of the new electrode structure.

    CiNii

  • LiNbO3 optical switch using asymmetric X-junction waveguide for broadband optical network node

    Takuya Sakamaki, Yu Narita, Hiroyuki Tsuda, Shinya Nakajima, Tetsuya Kawanishi

    IEICE Electronics Express   7 ( 5 ) 360 - 364  2010.03  [Refereed]

     View Summary

    Broadband optical switches are required for a wave-length division multiplexed photonic network node. The wavelength dependency of the LiNbO3 optical switch characteristics are mainly attributed to the directional coupler section. An asymmetric X-junction was suitable for a broadband optical switch because it has flat spectral response over wide wavelength range and it is easy to fabricate. We have optimized the structure of an asymmetric X-junction and fabricated the 1×2 LiNbO3 optical switches using it. The optical switch showed broad band characteristics compared to the switch with a directional coupler. © IEICE 2010.

    DOI

  • Simultaneous 3 x 10 Gbps optical data transmission in 1-mu m, C-, and L-wavebands over a single holey fiber using an ultra-broadband photonic transport system

    Yamamoto Naokatsu, Omigawa Yu, Akahane Kouichi, Kawanishi Tetsuya, Sotobayashi Hideyuki

    OPTICS EXPRESS   18 ( 5 ) 4695 - 4700  2010.03  [Refereed]  [International journal]

     View Summary

    An ultra-broadband photonic transport system has been developed to expand the usable wavelength bandwidth for optical communication. Simultaneous 3 x 10-Gbps error-free photonic transmissions are demonstrated in the 1-microm, C-, and L-wavebands by using the ultra-broadband photonic transport system over a 5.4-km-long holey fiber transmission line.

    DOI PubMed

  • Broadband wavelength-tunable ultrashort pulse source using a Mach-Zehnder modulator and dispersion-flattened dispersion-decreasing fiber

    Isao Morohashi, Takahide Sakamoto, Hideyuki Sotobayashi, Tetsuya Kawanishi, Iwao Hosako

    OPTICS LETTERS   34 ( 15 ) 2297 - 2299  2009.08  [Refereed]  [International journal]

     View Summary

    The broadband wavelength tunability of femtosecond pulse generation using a Mach-Zehnder-modulator-based flat-comb generator (MZ-FCG) and a dispersion-flattened dispersion-decreasing fiber (DF-DDF) was demonstrated. Near-Fourier-transform-limit picosecond pulses generated from the MZ-FCG were compressed into femtosecond pulses by adiabatic soliton compression. By tuning the wavelength of the input cw light, 200 fs, 10 GHz pulses were generated in the wavelength range of 1535 to 1570 nm. Such wide-range wavelength tunability was realized by both the independence of a comb-flattening condition from the inputted wavelength and the dispersion flatness of the DF-DDF. (C) 2009 Optical Society of America

    PubMed

  • Optical minimum-shift-keying transmitter based on a monolithically integrated quad Mach-Zehnder in-phase and quadrature modulator

    Guo-Wei Lu, Takahide Sakamoto, Akito Chiba, Tetsuya Kawanishi, Tetsuya Miyazaki, Kaoru Higuma, Junichiro Ichikawa

    OPTICS LETTERS   34 ( 14 ) 2144 - 2146  2009.07  [Refereed]  [International journal]

     View Summary

    We propose and demonstrate an optical minimum-shift-keying (MSK) transmitter using a single-quad Mach-Zehnder (MZ) in-phase and quadrature modulator, where four sub-Mach-Zehnder modulators are monolithically integrated on a main MZ superstructure. Using the proposed transmitter, a MSK signal at bit rate of B could be successfully generated by orthogonally superposing two low-speed (B/2) carrier-suppressed return-to-zero differential phase-shift-keying streams with a relative time offset, 1/B. MSK signals at bit rate of 20 and 80 Gbits/s were successfully generated using the proposed MSK transmitter. A continuous changed phase trajectory of the obtained MSK was confirmed using a complex spectrum analyzer. The filtering tolerance of the MSK was also characterized using a bandwidth-variable tunable filter. (C) 2009 Optical Society of America

    DOI PubMed

  • Tunable all-optical pulse compression and stretching via doublet Brillouin gain lines in an optical fiber

    Guanshi Qin, Takahide Sakamoto, Naokatsu Yamamoto, Tetsuya Kawanishi, Hideyuki Sotobayashi, Takenobu Suzuki, Yasutake Ohishi

    Optics Letters   34 ( 8 ) 1192 - 1194  2009.04  [Refereed]  [International journal]

     View Summary

    We demonstrate tunable all-optical pulse compression and stretching via doublet Brillouin gain lines in an optical fiber. Tunable pulse compression or a stretching ratio of 1.47-0.43 accompanying a time delay is achieved by controlling the separation between two gain lines, for an input pulse train with a 40 ns width and a repetition rate of 5 MHz,ina 4km silica fiber with a fixed pump power of 88.1 mW. The limitation of this pulse compressor or stretcher is also discussed. © 2009 Optical Society of America.

    DOI PubMed

  • Integrated lithium niobate Mach-Zehnder interferometers for advanced modulation formats

    Tetsuya Kawanishi, Takahide Sakamoto, Akito Chiba

    IEICE Transactions on Electronics   E92-C ( 7 ) 915 - 921  2009  [Refereed]

     View Summary

    We present recent progress of high-speed Mach-Zehnder modulator technologies for advanced modulation formats. Multi-level quadrature amplitude modulation signal can be synthesized by using parallel Mach-Zehnder modulators. We can generate complicated multi-level optical signals from binary data streams, where binary modulated signals are vectorially summed in optical circuits. Frequency response of each Mach-Zehnder interferometer is also very important to achieve high-speed signals. We can enhance the bandwidth of the response, with thin substrate. 87 Gbaud modulation was demonstrated with a dual-parallel Mach- Zehnder modulator. Copyright © 2009 The Institute of Electronics, Information and Communication Engineers.

    DOI

  • Adaptive threshold adjustment for signal-distortion-free digital-coherent optical demodulation system

    Akito Chiba, Takahide Sakamoto, Tetsuya Kawanishi

    OPTICS EXPRESS   16 ( 26 ) 21647 - 21655  2008.12  [Refereed]  [International journal]

     View Summary

    Optical quadrature amplitude modulation (QAM) attracts considerable attention in the enhancement of communications capacity, due to its high spectral efficiency. However, this modulation format is more sensitive to signal distortion than conventional formats, making it more difficult to create, transmit, and detect signals. In this paper, we propose an adaptive scheme for demodulation of the distorted optical signals with paying attention to use of DSP-technology. The scheme is based on the adjustment of the thresholds against the signal distortion. Successful demodulation of optical QAM signals is demonstrated with a sufficiently low bit-error rate. (C) 2008 Optical Society of America

    DOI PubMed

  • Simple, low fluctuation voltage signal generation for 8-Gb/s quadrature amplitude modulation using dual-parallel Mach-Zehnder modulator

    Akito Chiba, Takahide Sakamoto, Tetsuya Kawanishi, Masayuki Izutsu

    IEICE ELECTRONICS EXPRESS   5 ( 14 ) 497 - 502  2008.07  [Refereed]

     View Summary

    Optical quadrature amplitude modulation (QAM) has attracted considerable attention because of its high spectral efficiency. For high capacity, the modulation rate should also be enhanced, which requires the generation of high-baud-rate multilevel electric signals with high precision in amplitude. In this paper, we describe a method to reduce the amplitude fluctuation of the electric signal by adopting a return-to-zero (RZ) format. We also demonstrate 2.0-Gbaud optical QAM signal generation with a conventional dual-parallel Mach-Zehnder modulator (DPMZM) driven by the electric RZ data signals.

    DOI

  • Widely repetition-tunable 200 fs pulse source using a Mach-Zehnder-modulator-based flat comb generator and dispersion-flattened dispersion-decreasing fiber

    Isao Morohashi, Takahide Sakamoto, Hideyuki Sotobayashi, Tetsuya Kawanishi, Lwao Hosako, Masahiro Tsuchiya

    OPTICS LETTERS   33 ( 11 ) 1192 - 1194  2008.06  [Refereed]  [International journal]

     View Summary

    By combining a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) with a dispersion-flattened dispersion-decreasing fiber, femtosecond pulses have been generated from a cw light. Near-Fourier-transform-limit picosecond pulses generated from the MZ-FCG were compressed into femtosecond order by pulse compression. Our system enables flexible tuning of the repetition rate and pulse width, because those depend on the driving signal of the MZ-FCG. Pulse trains of 200 fs width were continuously and stably generated without mode hopping, with a repetition rate range from 5 to 17 GHz. Our system consists of a modulator and compression fiber; thus, the configuration is simpler and more stable. (C) 2008 Optical Society of America.

    PubMed

  • 10 GHz, 2.4 ps pulse generation using a single-stage dual-drive Mach-Zehnder modulator

    Takahide Sakamoto, Tetsuya Kawanishi, Masahiro Tsuchiya

    Optics Letters   33 ( 8 ) 890 - 892  2008.04  [Refereed]  [International journal]

     View Summary

    This Letter reports on picosecond pulse generation at a repetition of 10 GHz by using a single-stage electrooptic LiNbO3 Mach-Zehnder modulator, stressing the simplicity of its setup. It is analytically and experimentally proved that dual-arm modulation with in-phase sinusoidal signals having slightly different amplitudes generated a highly coherent optical comb with a great spectral flatness and a parabolic phase relationship in its spectrum. The generated comb was Fourier synthesized and shaped into an ultrashort pulse train with an optical bandpass filter and a dispersive fiber. The pulse source was highly stable, exhibiting an ultralow timing jitter of less than 130 fs. © 2008 Optical Society of America.

    DOI PubMed

  • Multiple optical code-label processing using multi-wavelength frequency comb generator and multi-port optical spectrum synthesizer

    Fumi Moritsuka, Naoya Wada, Takahide Sakamoto, Tetsuya Kawanishi, Yuki Komai, Shimako Anzai, Masayuki Izutsu, Kashiko Kodate

    Optics Express   15 ( 12 ) 7515 - 7521  2007.06  [Refereed]  [International journal]

     View Summary

    In optical packet switching (OPS) and optical code division multiple access (OCDMA) systems, label generation and processing are key technologies. Recently, several label processors have been proposed and demonstrated. However, in order to recognize N different labels, N separate devices are required. Here, we propose and experimentally demonstrate a large-scale, multiple optical code (OC)-label generation and processing technology based on multi-port, a fully tunable optical spectrum synthesizer (OSS) and a multi-wavelength electro-optic frequency comb generator. The OSS can generate 80 different OC-labels simultaneously and can perform 80-parallel matched filtering. We also demonstrated its application to OCDMA. © 2007 Optical Society of America.

    DOI PubMed

  • Asymptotic formalism for ultraflat optical frequency comb generation using a Mach-Zehnder modulator

    Takahide Sakamoto, Tetsuya Kawanishi, Masayuki Izutsu

    Optics Letters   32 ( 11 ) 1515 - 1517  2007.06  [Refereed]  [International journal]

     View Summary

    We theoretically prove that a conventional Mach̶Zehnder modulator can generate an optical frequency comb with excellent spectral flatness. The modulator is asymmetrically dual driven by large amplitude sinusoidal signals with different amplitudes. The driving condition to obtain spectral flatness is analytically derived and optimized, yielding a simple formula. This formula also predicts the conversion efficiency and bandwidth of the generated frequency comb. © 2007 Optical Society of America.

    DOI PubMed

  • Optical amplification characteristics of Ti-diffused waveguides on Erbium-doped LiNbO3 crystal

    So Kogahara, Satoshi Shinada, Shinya Nakajima, Tetsuya Kawanishi, Hirochika Nakajima, Masayuki Izutsu

    IEICE ELECTRONICS EXPRESS   4 ( 4 ) 134 - 139  2007.02  [Refereed]

     View Summary

    We have first fabricated and characterized Ti-diffused channel waveguides on Er-doped LiNbO3 single crystal. We achieved an optical gain of 2.1 dB/cm at 1531.4 nm signal light (TM mode) by optical pumping at 1480 nm with pump power of 200 mW/port for a 40 mm long Ti-diffused Z-cut 0.5 mol% Er-doped LiNbO3 waveguide. The total gain of a pig tailed device was 3.8 dB.

    DOI

  • Novel functionality and material for Si-photonics: Two-photon absorption switching and antimonide hetero-genius epitaxy

    Liang Tak-Keung, Akahane Kouichi, Yamamoto Naolkatsu, Nunes Luis Romeu, Kawanishi Tetsuya, Tsuchiya Masahiro

    IEICE TRANSACTIONS ON ELECTRONICS   E90C ( 2 ) 409 - 414  2007.02  [Refereed]

    DOI

  • A Resonant Type LiNbO3 Optical Modulator Array with Micro-Strip Antennas.

    Satoshi Shinada, Tetsuya Kawanishi, Masayuki Izutsu

    IEICE Transactions on Electronics   90-C ( 5 ) 1090 - 1095  2007

    DOI

  • Low-temperature Au-to-Au bonding for LiNbO3/Si structure achieved in ambient air

    Ryo Takigawa, Eiji Higurashi, Tadatomo Suga, Satoshi Shinada, Tetsuya Kawanishi

    IEICE TRANSACTIONS ON ELECTRONICS   E90C ( 1 ) 145 - 146  2007.01  [Refereed]

     View Summary

    A lithium mobate (LiNbO3)/silicon (Si) hybrid structure has been developed by the surface-activated bonding of LiNbO3 chips with gold (Au) thin film to Si substrates with patterned Au film. After organic contaminants on the An surfaces were removed using argon radio-frequency plasma, Au-to-Au bonding was carried out in ambient air. Strong bonding at significantly low temperatures below 100 degrees C without generating cracks has been demonstrated.

    DOI

  • An optical grating filter dry-etched on a LiNbO3 substrate

    Satoshi Shinada, Tetsuya Kawanishi, Takahide Sakamoto, Masayuki Izutsu

    IEICE Electronics Express   3 ( 14 ) 347 - 352  2006.07  [Refereed]

     View Summary

    We fabricated an etched grating filter on a Ti-diffused waveguide in LiNbO3 using inductively coupled plasma etching with C 4F8/Ar as an etching gas, which has an etching rate of 85.1 nm/min. The etched grating filter had a reflectivity of 35% and a bandwidth of 0.02 nm. Maximum reflectivity was obtained when the electric field of an incident beam was perpendicular to the grating. © IEICE 2006.

    DOI

  • A bias condition monitor technique for the nested Mach-Zehnder modulator

    Kaoru Higuma, Shingo Mori, Tetsuya Kawanishi, Masayuki Izutsu

    IEICE Electronics Express   3 ( 11 ) 238 - 242  2006.06  [Refereed]

     View Summary

    A nested Mach-Zehnder (MZ) modulator, which consists of two sub MZ interferometers embedded in a main MZ interferometer, is a multifunctional modulator. It can work as an optical single side-band (SSB) modulator, a differential quadrature phase shift keying (DQPSK) modulator and so on. Despite difficulties due to their complex structure, in order to avoid the operation instability of such modulators the bias condition of each MZ interferometer must be controlled automatically according to the modulation formats. In this paper, we proposed a specific bias condition monitor technique to the nested modulator. © IEICE 2006.

    DOI

  • High-speed optical DQPSK and FSK modulation using integrated Mach-Zehnder interferometers

    T Kawanishi, T Sakamoto, T Miyazaki, M Izutsu

    OPTICS EXPRESS   14 ( 10 ) 4469 - 4478  2006.05  [Refereed]  [International journal]

     View Summary

    We investigated an integrated optical modulator consisting of two Mach-Zehnder interferometers. The modulator can generate optical signals in various types of modulation formats, which have advantages for long-haul transmission, optical labeling, etc. By using a fabricated versatile optical modulator having traveling-wave electrodes designed for high-speed signals, we demonstrated generation of optical 40 Gb/s frequency-shift-keying signals, which can be demodulated by an optical filter. 80 Gb/s optical differential quadrature-shift-keying modulation was also demonstrated, where 40 Gb/s in-phase and quadrature data were, simultaneously, fed to the modulator. (c) 2006 Optical Society of America.

    PubMed

  • Optoelectronic oscillator using a LiNbO3 phase modulator for self-oscillating frequency comb generation

    Takahide Sakamoto, Tetsuya Kawanishi, Masayuki Izutsu

    Optics Letters   31 ( 6 ) 811 - 813  2006.03  [Refereed]  [International journal]

     View Summary

    Optical frequency comb generation by using a novel optoelectronic oscillator (OEO) is proposed and demonstrated with the emphasis placed on self-oscillating operation. In the OEO, a wideband LiNbO3 phase modulator is driven with a large-amplitude radio-frequency (RF) feedback signal to generate a deeply phase-modulated light wave
    accordingly, an optical frequency comb with a bandwidth greater than the RF signal is generated by self-oscillation. Although it generates multifrequency components, the OEO exhibits characteristics of a single-mode oscillator. Its operation is stable and self-starting. An optical frequency comb with a 120 GHz bandwidth and 9.95 GHz frequency spacing was successfully generated by self-oscillation at a single frequency. © 2006 Optical Society of America.

    DOI PubMed

  • Optical filter characterization by using optical frequency sweep technique with a single sideband modulator

    Tetsuya Kawanishi, Takahide Sakamoto, Masayuki Izutsu

    IEICE ELECTRONICS EXPRESS   3 ( 3 ) 34 - 38  2006.02  [Refereed]

     View Summary

    We demonstrated optical filter characterization using optical frequency sweep with optical single sideband modulation technique, where the frequency shift range was 2GHz-10 GHz. Undesired sidebands generated in the single sideband modulation due to electric phase errors can be compensated by automatic synchronized bias control. Fine pass band structures of a dual-section FBG were precisely measured, where the bandwidths of the pass bands were 440 MHz.

    DOI

  • Optical minimum-shift keying with external modulation scheme

    Takahide Sakamoto, Tetsuya Kawanishi, Masayuki Izutsu

    Optics Express   13 ( 20 ) 7741 - 7747  2005.10  [Refereed]  [International journal]

     View Summary

    We propose an optical initial phase control technique for external modulation in the format of minimum-shift keying (MSK). In this scheme, the optical phase discontinuities inherent to external frequency-shift-keying (FSK) modulation are compensated by use of an initial phase controller in conjunction with a FSK modulator. We present the principle of the control method and then numerically and experimentally prove that the signal has a modulation spectrum more compact than that of conventional binary phase-shift keying. 10-Gbit/s external modulation in MSK format was experimentally demonstrated. © 2005 Optical Society of America.

    DOI PubMed

  • All-optical modulation format conversion from frequency-shift-keying to phase-shift-keying

    Tetsuya Kawanishi, Takahide Sakamoto, Masayuki Izutsu

    Optics Express   13 ( 20 ) 8038 - 8044  2005.10  [Refereed]  [International journal]

     View Summary

    We have realized a novel optical modulation format conversion using double-sideband suppressed-carrier modulation. An optical wideband frequency-shift-keying (FSK) signal, generated by an external FSK modulator, can be directly converted into an optical phase-shift-keying (PSK) signal, where the FSK signal having two spectral components was fed to an optical intensity modulator followed by an optical bandpass filter. Optical frequency of the FSK signal was mapped into optical phase of the bandpass filter output whose phase deviation depends on a chirp of the FSK signal. We demonstrated modulation format conversion from FSK to PSK at 10 Gbps, by using a high-speed optical FSK modulator and a dual electrode Mach-Zehnder intensity modulator. © 2005 Optical Society of America.

    DOI PubMed

  • Pulse-carving technique for suppressing transient state in external wideband FSK modulation

    Takahide Sakamoto, Tetsuya Kawanishi, Masayuki Izutsu

    IEICE ELECTRONICS EXPRESS   2 ( 7 ) 244 - 248  2005.04  [Refereed]

     View Summary

    A novel pulse-carving technique for an externally-modulated wideband frequency-shift-keying (FSK) format is proposed. Synchronous intensity modulation on the FSK signal suppresses undesired transient components generated during the bit transition time. Numerical analysis for the pulse-carving technique employing a Mach-Zehnder modulator driven by a sinusoidal signal indicates that the suppression of the components is typically more than 20 dB.

    DOI

  • Programmable Coupler Ladder Based on Lithium Niobate Y-Junction Reflector.

    Jianxiao Chen, Tetsuya Kawanishi, Kaoru Higuma, Satoshi Shinada, William S. C. Chang, Masayuki Izutsu, Paul K. L. Yu

    IEICE Transactions on Electronics   88-C ( 3 ) 379 - 384  2005

    DOI

  • 10Gbit/s FSK transmission over 95km SMF using a LiNbO3 modulator

    Fujita Takahisa, Kawanishi Tetsuya, Higuma Kaoru, Ichikawa Junichiro, Shinada Satoshi, Sakamoto Takahide, Izutsu Masayuki

    IEICE Electron. Express   2 ( 1 ) 32 - 36  2005

     View Summary

    We demonstrate high-speed optical frequency-shift-keying (FSK) transmission over a 95km single-mode fiber (SMF) at 10Gbit/s using a LiNbO3 optical FSK modulator and an optical interleaver. The measured eye diagrams, bit error rate (BER) performances and optical spectrum indicate the FSK modulation is similar to zero chirp non-return-to-zero (NRZ) on-off-keying (OOK) transmission. Therefore, in view of dispersion tolerance, the FSK modulation can be treated as well as NRZ OOK.

    DOI CiNii

  • Integrated reciprocating optical modulator using phase-shifted fiber Bragg grating

    Tetsuya Kawanishi, Satoshi Oikawa, Kiichi Yoshiara, Satoshi Shinada, Takahide Sakamoto, Masayuki Izutsu

    IEICE Electronics Express   2 ( 2 ) 49 - 53  2005  [Refereed]

     View Summary

    We fabricated an integrated reciprocating optical modulator consisting of a phase-shifted fiber Bragg grating and an optical high-speed phase modulator. High-order double sideband components were effectively generated by reciprocating modulation process. We also demonstrated photonic millimeter-wave generation by feeding the double-sideband components to a high-speed photodetector. © 2005, The Institute of Electronics, Information and Communication Engineers. All rights reserved.

    DOI

  • Optical FSK transmission with group delay compensated balance detection

    Tetsuya Kawanishi, Takahisa Fujita, Kaoru Higuma, Junichiro Ichikawa, Takahide Sakamoto, Masayuki Izutsu

    ieice electronics express   2 ( 11 ) 333 - 337  2005  [Refereed]

     View Summary

    A novel balance detection scheme for high-speed optical frequency-shift-keying (FSK) transmission wasproposed. Fiber dispersion can be compensated by a balanced photodetector with an optical delay. 10 Gbit/s optical FSK transmission over a 130 km single mode fiber was demonstrated, where the FSK signal was generated byusing a LiNbO3 high-speed optical FSK modulator. © 2005, The Institute of Electronics, Information and Communication Engineers. All rights reserved.

    DOI

  • Amplitude modulation on millimeter-wave signal with low driving voltageusing reciprocating optical modulator

    Takahide Sakamoto, Tetsuya Kawanishi, Satoshi Shinada, Masayuki Izutsu

    ieice electronics express   2 ( 7 ) 239 - 243  2005  [Refereed]

     View Summary

    A reciprocating optical modulator (ROM) generates a millimeter-wave signal in good efficiency. Internal bias modulation on a ROM is reported, in this paper. Owing to reciprocating modulation in the ROM, the driving voltage required for amplitude modulation on a millimeter-wave signal is highly decreased. In this paper, a millimeterwave signal in the 52.8-GHz frequency band is amplitude-modulated with a low-voltage (2.0 V) baseband signal, where half-wave voltage of the modulator embedded in the ROM is 6.4 V. © 2005, The Institute of Electronics, Information and Communication Engineers. All rights reserved.

    DOI

  • Optical frequency comb generator using optical fiber loops with single-sideband modulation

    Tetsuya Kawanishi, Takahide Sakamoto, Satoshi Shinada, Masayuki Izutsu

    IEICE Electronics Express   1 ( 8 ) 217 - 221  2004  [Refereed]

     View Summary

    This paper describes optical frequency comb generation using optical single-sideband modulation technique. We can obtain optical frequency shift using the singnal-sideband modulator consisting of four optical phase modulators, where the frequency shift is precisely equal to that of an rf-signal fed to the modulator. A series of optical spectral components can be generated by using an optical fiber loop having an optical single-sideband modulator. © 2004, The Institute of Electronics, Information and Communication Engineers. All rights reserved.

    DOI

  • Optical FSK/IM Signal Generation Using an Integrated Optical FSK Modulator

    Tetsuya Kawanishi, Satoshi Shinada, Takahide Sakamoto, Masayuki Izutsu, Kaoru Higuma, Takahisa Fujita, Junichiro Ichikawa

    IEICE Electronics Express   1 ( 3 ) 69 - 72  2004  [Refereed]

     View Summary

    We demonstrate simultaneous optical modulation by frequency shift keying (FSK) and intensity modulation (IM) using a newly developed high-speed FSK modulator, for optical packet systems where payload and label signals are, respectively, in IM and FSK format. The modulator consists of four optical phase modulators, with travelingwave electrodes to obtain high-speed frequency switching and large frequency deviation in FSK modulation. © 2004, The Institute of Electronics, Information and Communication Engineers. All rights reserved.

    DOI

  • Near-field intensity distribution of waves scattered from slightly rough surfaces.

    Tetsuya Kawanishi

    Journal of the Optical Society of America. A, Optics, image science, and vision   19 ( 2 ) 398 - 403  2002.02  [International journal]

     View Summary

    The near fields of electromagnetic waves scattered from two-dimensional slightly rough surfaces are studied by using the stochastic functional approach. The correlation coefficient between the surface and the intensity of the scattered-wave field is investigated to estimate the fidelity of near-field intensity images. We show that the fidelity depends on both the polarization and the angle of incidence and that high fidelity can be obtained by a TM-polarized incident wave whose incident angle is not close to the critical angle of the total reflection.

    PubMed

  • Optimum detection for extracting maximum information from symmetric qubit sets

    Jun Mizuno, Mikio Fujiwara, Makoto Akiba, Tetsuya Kawanishi, Stephen M. Barnett, Masahide Sasaki

       2001.06

     View Summary

    We demonstrate a class of optimum detection strategies for extracting the
    maximum information from sets of equiprobable real symmetric qubit states of a
    single photon. These optimum strategies have been predicted by Sasaki et al.
    [Phys. Rev. A{\bf 59}, 3325 (1999)]. The peculiar aspect is that the detections
    with at least three outputs suffice for optimum extraction of information
    regardless of the number of signal elements. The cases of ternary (or trine),
    quinary, and septenary polarization signals are studied where a standard von
    Neumann detection (a projection onto a binary orthogonal basis) fails to access
    the maximum information. Our experiments demonstrate that it is possible with
    present technologies to attain about 96% of the theoretical limit.

    DOI

▼display all

Books and Other Publications

Research Projects

  • Photonic Computing Highlighting Ultimate Nature of Light

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2022.06
    -
    2027.03
     

  • 総括班

    日本学術振興会  科学研究費助成事業

    Project Year :

    2022.06
    -
    2027.03
     

    成瀬 誠, 鯉渕 道紘, 川上 哲志, 内田 淳史, 川西 哲也, 砂田 哲, 笠松 章史

     View Summary

    本学術変革領域研究の初年度にあたり、総括班においては領域の立ち上げに関わる内容を中心に事業を推進した。まず、領域会議を2022年8月及び2023年3月の2回開催し、領域内の相互理解、相互連携、及び具体的協働の促進を図った。また、2023年3月27日には第1回公開シンポジウムをハイブリッド開催し(東京大学伊藤国際学術研究センター 伊藤謝恩ホール)、200名を超える応募者を集め、大変盛況であった。フォトニックコンピューティング分野における産学連携は重要課題の一つであり、その最初の取り組みとして2022年12月6日に浜松ホトニクスを訪問し、見学会とワークショップを実施した。さらに、領域内の相互理解と具体的協働の促進を図ることを目的として、「ARC×光」研究会を原則毎月開催(合計7回)し、議論を深めた。そして、次年度以降のアウトリーチ活動のコンセプト設計と実際的展開を検討し、2023年度中に合計8回の「光×コンピューティング」オープンセミナー、「光と情報」サマースクール、及び第1回国際シンポジウムを実施することを設計し、その準備を進めた。また本領域が初期段階であることを踏まえ、日本光学会年次学術講演会「Optics & Photonics Japan 2022」(宇都宮大学、2022年11月15日)及び電子情報通信学会総合大会(芝浦工業大学、2023年3月7日)にて公開シンポジウムを開催した。
    さらに、計画研究を跨がる領域内連携の具体化を期初より推進し、複数の計画研究の研究者からなる共著論文の出版実績を得た。特に、採択時に領域全体との関連性を指摘されたC02に関して、B01及びB03と共著の原著論文がAIP Advances誌にEditor's Pickとして採択された。

  • Innovative Photonic Computing using Advanced Optical Modulation

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Transformative Research Areas (A)

    Project Year :

    2022.06
    -
    2027.03
     

  • 知的交通・地域通信網を実現する低コスト製造技術による無線・光融合アクセスネットワーク

    科学技術振興機構  国際的な科学技術共同研究などの推進 国際科学技術共同研究推進事業 SICORP e-ASIA JRP

    Project Year :

    2023
    -
    2025
     

    川西 哲也

     View Summary

    当分野は2013年の開始以来、副題に先端技術融合のターゲットとして、インテリジェント社会インフラを据えてきた。社会インフラの基本機能は、同概念の起源である古代ギリシア以来、1生命の維持、2コミュニティーの維持、3文明の維持、であるとの立場から、1の代表として水インフラ、2の代表として交通インフラ、3の代表としてエネルギーインフラを指定し、e-ASIA各国との共同研究に過去約10年にわたって取り組んできた。今回の公募は1~3を貫く概念として、環境とデジタルを特に強調してGDC(Greener Digital Cities)を新たに掲げた。特に2に関してCOVID-19下で通信が果たした役割の大きさに鑑み、通信インフラをGDC研究の要素に明示した。GDCの通信インフラの中核機能はユーザーやセンサーから送受される多量の情報を効率的に収集・解析することである。
    本課題では、地域アクセスネットワークの高度化を目的として、無線と光ファイバーの融合による通信・センシング技術を日本・タイ・フィリピンで共同研究開発する。具体的には、道路-車両間の情報の取得・解析による歩行者保護・衝突防止を主眼とするスマート交通システムおよび低コスト地域高速データ通信網の実現を目標とする。日本チームはミリ波無線、光無線などを融合させた無線・光融合アクセスネットワークの研究開発を、タイチームは知的交通に向けたAI解析やモニタリング・センシング技術を、フィリピンチームはセンシング・通信実現のための低コスト両用光デバイス技術の研究開発を行う。
    各チームが持つ強い基礎・基盤分野において新技術が生まれるとともに、それらを効果的に組み合わせる国際共同フィールド試験を通じて、GDCの早期の社会実装に向けたシステム技術の開発が期待できる。

  • Optical Discrete Time-Frequency Transform for Ultrafast Communications

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2018.04
    -
    2023.03
     

  • Instantaneous Frequency Measurement by asymmetric double side-band optical modulation

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2018.04
    -
    2021.03
     

    Kawanishi Tetsuya

     View Summary

    The purpose of this study is to realize instantaneous frequency measurement for broadband signals using optical modulation techniques. We proposed a system that directly reads the frequency of a high-frequency signal from the ratio of the sidebands produced by the modulation, enabling measurement without being affected by the intensity fluctuations of the light source or the signal to be measured. In addition, we proposed a configuration that improves the measurement accuracy and realizes direct conversion of frequency to digital signal by parallelization. As a result, we were able to measure the instantaneous frequency of a broadband signal (13.5-14.5 GHz) with a sweep speed of 100 ns with a relative error of less than 0.1%. We believe that this research will realize the effective use of radio waves and open up a new field of signal measurement.

  • Research on high-speed ranging technique using optical and radio frequency comb signals

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2016.04
    -
    2019.03
     

    Kanno Atsushi

     View Summary

    In this study, optical-frequency-comb-based ranging technique is studied and developed using an FM-CW radar signals for high-precision ranging system. Optical modulation technique helps generating optical components with a high coherency each other by a single lightwave source. In the scheme, the FM-CW optical signals, which is provided by the comb components, has strong correlation in the waveforms. Therefore, multiple signal classification (MUSIC) technique can be applied to identify the beat notes in the FM-CW reception system. Finally, the high-precision ranging results are provided by the optical frequency comb system. Also, we developed high-precision millimeter-wave signal generation by the optical frequency comb source and broadening technique of the optical frequency comb bandwidths by synchronization of multiple frequency comb signals. We hope these fundamental technique will help realizing high-precision ranging solutions based on the frequency combs

  • Optical time-frequency multiplexer for high-speed and high-density optical communication networks

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2015.04
    -
    2019.03
     

    Sakamoto Takahide

     View Summary

    For future ultrafast optical communication, we need to realize practical optical multiplexing techniques, where multiple optical channels are bundled and multiplexed in a fiber. In conventional approaches, high-resolution optical filters like arrayed waveguide gratings (AWGs) are typically used for the optical multiplexing. In this research, we proposed and demonstrated a novel optical multiplexer called optical time-frequency multiplexer. By using the technology, we have successfully demonstrated optical multiplexing and transmission at 160 Gb/s

  • Two-mode quantum dot laser for terahertz generation

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2015.04
    -
    2018.03
     

    Akahane Kouichi

     View Summary

    In this study, we fabricated two-mode laser using semiconductor InAs quantum dots as the gain medium in the external cavity configuration. When the QDs were used for gain media, the mode hopping could be suppressed and stable two-mode lasing was obtained. Two-mode laser emission with a separation of 0.09, 0.1, 0.3, and 1 THz has been achieved by controlling the etalon and narrow-band filter setting and corresponding beat signal was observed in interference measurement. From these results, the fabricated two-mode laser can be used for generation of terahertz wave

  • Development of millimeter-wave/THz-wave generation devices utilizing a high-Q resonator and nonlinear-optical difference frequency generation

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2012.04
    -
    2014.03
     

    MURATA Hiroshi, KAWANISHI Tetsuya, KANNO Atsushi

     View Summary

    New millimeter-wave/terahertz-wave signal generation devices utilizing nonlinear optical difference frequency generation (DFG) in a rectangular waveguide resonator were studied in detail. By using detailed analyses based-on the coupled-mode theory and the finite-domain time-domain (FDTD) method, basic device operations were identified and a proto-type device operating in the 60GHz-band was designed. In the experiment, 60GHz signal generation was successfully demonstrated in the fabricated device using LiTaO3 crystal. The measured frequency response of the generated DFG signal was in good agreement with the theoretical one. In addition, the applications of the DFG technique to optical cross-/auto-correlation devices were also proposed and expected characteristics were shown theoretically. The fusion with standard rectangular waveguide circuits and higher frequency signal generation in the terahertz ranges were also discussed

  • テラビットルータとスーパーコンピュータのための1024×1024 光スイッチング技術

    国際的な科学技術共同研究などの推進 戦略的国際科学技術協力推進事業 SICP シンガポール

    Project Year :

    2010
    -
    2012
     

    川西 哲也

     View Summary

    本研究交流は、同時並行的に日本側がスイッチングデバイス要素技術開発を行い、シンガポール側がスイッチシステムの研究を行うことで、大規模光スイッチ技術を確立することを目的とする。 具体的には、日本側がデバイス要素技術としてニオブ酸リチウムによる超高速スイッチ技術、量子ドット光アンプと光分岐回路による大規模スイッチ技術に関する研究開発を行い、シンガポール側がアレイ導波路(AWG)を利用したルータ(AWGR)のシステム構成新規検討および研究開発を行う。デバイスの高効率化により、デバイス自体で消費される電力および排熱のための冷却システムに要するエネルギーの削減を実現し、省エネルギーと高性能化の両立を目指す。 両国の研究チームが相互補完的に取り組むことで、大規模光スイッチ技術の開発が期待されるとともに、スイッチングデバイスの国際標準化への貢献も期待される。

  • 分極反転構造を用いた高機能電気光学変調器の開発

    日本学術振興会  科学研究費助成事業

    Project Year :

    2007
    -
    2008
     

    村田 博司, 塩見 英久, 川西 哲也, 坂本 高秀

     View Summary

    本研究は、研究代表者が提案している"分極反転構造を用いた高速電気光学変調技術"を利用して、新しい小型高性能光FSK(Frequency-Shift Keying)変調器を開発することを目的とする。本年度は下記の研究成果を得た。
    1. 25GHz帯光FSK変調器の設計これまでの研究成果をベースとして、オフセット周波数25GHz帯で動作する光FSK変調器の動作解析および設計を行った。特に、良好な光FSK変調特性を得るために3つの変調電極(オフセット変調信号用電極、データ信号用電極、動作点調整用電極)を用いた新しいデバイス構成を考案した。光導波路は我々が提案している3分岐導波路干渉計を用いて、分極反転構造による変調特性制御技術を駆使した構成とした。基板としてz-cut LiNbO_3およびz-cut LiNbO_3を用いた場合について、デバイスの設計を行った。
    2. 試作・動作実験設計した25GHz帯光FSK変調器の試作・動作実を行った。波長1.55μm光を用いて実験を行ったところ、3分岐導波路干渉計の良好な干渉特性を確認することに成功した。干渉計の消光比としては25dB以上が得られた。また、オフセット変調信号に対する動作を調べたところ、設計周波数25GHzを中心とする帯域動作変調特性を確認した。さらに、オフセット変調信号とデータ信号を同時に入力した時の動作を詳しく調べたところ、データ信号に応じて光変調サイドバンド成分の比が大きく変化することを確かめた。オフセット変調信号による変調指数を大きく取ることにより、良好な光FSK変調特性が得られることを確かめた。

  • 往復逓倍変調を利用した波長多重光無線信号一括発生技術に関する研究

    日本学術振興会  科学研究費助成事業

    Project Year :

    2005
    -
    2007
     

    川西 哲也

     View Summary

    本研究では一つのデバイスで複数のファイバ無線信号の一括生成を可能とする光変調技術の実現を目指している。光の往復を利用し,高速信号発生を可能とする往復逓倍変調器を利用する。往復逓倍変調器は2つの光フィルタと1つの光位相変調器から構成され,所定の無線信号周波数と入力光波長の組み合わせに対して高効率で動作する。これにより,光位相変調器部分に印加する電気信号よりも遙かに高速の成分を持つ光変調信号の発生が可能となる。これまでに400GHzを超える超高速信号発生に成功している。この往復逓倍変調器を含め,これまでの光信号発生では,複数の信号を発生させる場合には,それぞれに変調デバイスを準備する必要があり,波長多重で容量拡大する場合に,送信機が複雑になるという問題があった。これに対し,多波長成分の入力に対しては光フィルタが複数の反射帯域,透過帯域をもつものとすることで,一括信号生成が可能とする,新たな方式を検討する。各反射帯域がそれぞれ異なる反射点をもつようにすることで,波長成分ごとに異なる周波数の無線信号での変調が実現でき,非常にシンプルな構成で,各波長成分をそれぞれ別の無線信号で同時に変調することが可能となる。今年度は,数チャネルで一括信号発生可能な往復逓倍変調器の変調効率向上を図るために,光増幅機能をもった導波路構造に関する研究を進めた。エルビウムを添加することにより変調器内部での光損失を補償する原理の確認については昨年度完了しているが,今年度,往復逓倍変調器に適用し,ファイバ無線信号の発生効率の向上を達成した。さらに,複数チャネル同時変調の実証実験を行い,多数のチャネルで同時変調が可能であることを確認した

  • 分極反転構造を用いた高機能電気光学変調器の開発

    日本学術振興会  科学研究費助成事業

    Project Year :

    2006
     
     
     

    村田 博司, 塩見 英久, 川西 哲也, 坂本 高秀

     View Summary

    本研究は、研究代表者が提案している"分極反転構造を用いた高速電気光学変調技術"を利用して、新しい小型高性能光FSK(Frequency-Shift Keying)変調器を開発することを目的とする。本年度は下記の研究成果を得た。1. 25GHz帯光FSK変調器の設計これまでの研究成果をベースとして、オフセット周波数25GHz帯で動作する光FSK変調器の動作解析および設計を行った。特に、良好な光FSK変調特性を得るために3つの変調電極(オフセット変調信号用電極、データ信号用電極、動作点調整用電極)を用いた新しいデバイス構成を考案した。光導波路は我々が提案している3分岐導波路干渉計を用いて、分極反転構造による変調特性制御技術を駆使した構成とした。基板としてz-cut LiNbO_3およびz-cut LiNbO_3を用いた場合について、デバイスの設計を行った。2. 試作・動作実験設計した25GHz帯光FSK変調器の試作・動作実を行った。波長1.55μm光を用いて実験を行ったところ、3分岐導波路干渉計の良好な干渉特性を確認することに成功した。干渉計の消光比としては25dB以上が得られた。また、オフセット変調信号に対する動作を調べたところ、設計周波数25GHzを中心とする帯域動作変調特性を確認した。さらに、オフセット変調信号とデータ信号を同時に入力した時の動作を詳しく調べたところ、データ信号に応じて光変調サイドバンド成分の比が大きく変化することを確かめた。オフセット変調信号による変調指数を大きく取ることにより、良好な光FSK変調特性が得られることを確かめた

  • Study on the resonant type optical modulator array with antennas for a conversion of milli-wave to optical wave

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2004
    -
    2005
     

    IZUTSU Masayuki, TSUCHIYA Masahiro, KAWANISHI Tetsuya, SHINADA Satoshi, NAKAJIMA Hirochika

     View Summary

    A resonant type optical modulator array with antennas can be an effective converter from micro/millimeter-wave to light wave for the uplink of the radio on fiber system. For realizing this novel device, we have tried the following three themes.1.Realization of a 10 GHz band resonant type LiNbO_3 optical modulator.We designed and fabricated the resonant type modulator with a stub electrode or a capacitor, which could work for impedance matching. We clarified that the resonant frequencies and the induced phase shift were strongly depended on the impedance match structure. The half wave voltage of 15 V and 10 GHz operation were demonstrated.2.Fabrication of a 10 GHz band antenna and integration of the modulators and the antennas.We fabricated micro strip antennas with resonant frequency of 10 GHz and connected them to four modulators aligned on the optical waveguide of LiNbO_3 by using coaxial metal cable. The highbred integration of the modulators and the antennas was demonstrated.3.Demonstration of the modulator array operated by the received power of the antennas.We tried micro wave receiving by the antennas connected to the modulators. A 10 GHz sinusoidal signal was generated from a horn antenna, and irradiated to the antennas. We demonstrated that four aligned modulators could be simultaneously driven by the power received. One percent modulation could be obtained at the input power of 31 dBm to the horn antenna and the distance of 1 m. We confirmed that the optical phase shift induced by the received power was proportional to the number of connected antennas and inversely proportional to the distance between two antennas. More number of arrays will give us an applicative larger phase shift. We demonstrated that our proposed device is available as the converter of the milli-wave to the optical wave

▼display all

Misc

  • Wired and wireless seamless networks by photonics

    Tetsuya Kawanishi, Atsushi Kanno, Pham Tien Dat, Toshimasa Umezawa, Naokatsu Yamamoto

    JPhys Photonics   2 ( 1 ) 012001 - 012001  2020.01

     View Summary

    Demand for wireless services is increasing rapidly, due to deep penetration of mobile terminals, such as smartphones. Radio spectrum congestion is an important issue, even for conventional mobile services. One of the possible solutions would be to use wired and wireless seamless networks consisting of radio and optical links, where huge data traffic can be offloaded from radio-waves in the air to optical signals over fibres. This paper provides seamless network configurations which can be applied to 90-GHz high-speed wireless links and high-resolution radars. We focus on applications for public transportation systems including airport runways, railways, etc.

    DOI

  • Photonic systems and devices for linear cell radar

    Tetsuya Kawanishi, Atsushi Kanno, Pham Tien Dat, Toshimasa Umezawa, Naokatsu Yamamoto

    Applied Sciences (Switzerland)   9 ( 3 )  2019.02

     View Summary

    This paper reviews linear cell radar systems, which are radar systems consisting of many antenna units connected by radio-over-fiber to monitor linear-shaped areas. A linear cell system using a millimeter-wave band can provide high-resolution imaging for foreign object detection on runways. Electro-optic devices play important roles in linear cell systems to provide a conversion between optical and electric signals. This paper describes overviews of such devices including light sources, photodetectors, and optical modulators, etc.

    DOI

  • マッハ‐ツェンダー型光変調器を用いた周回型光コム発生器による広帯域光コム生成 ―変調器駆動電圧への二次高調波印加の効果―

    森 脩也, 山口剛史, 川西哲也, 戸田裕之

    レーザー学会学術講演会第38回年次大会     25aIX-3  2018.01

  • 90GHz Optical Phase Modulator Using Slotted Patch Antennas on Thin LiNbO₃ Optical Crystal (マイクロ波)

    WIJAYANTO Yusuf Nur, KANNO Atsushi, KAWANISHI Tetsuya

    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報   115 ( 142 ) 149 - 154  2015.07

    CiNii

  • LiNbO3基板上でのブランチラインカップラの小型化の検討と電気光学光SSB変調素子への応用

    山本勝之, 榎原晃, 河合正, 川西哲也

    輻射科学研究会資料集   2014  2015

    J-GLOBAL

  • Influence of harmonic distortions of driving signal on the measurement of Mach-Zehnder modulator parameters

    Y. Nishi, N. Ichino, T. Hayashi, H. Toda, T. Kawanishi

    International Topical Meeting on Microwave Photonics / Asia-Pacific Microwave Photonics Conference (MWP/APMP 2014)     TuEB-5  2014.10  [Refereed]

  • C-14-2 Low-Chip Electro-Optic intensity modulator using 23 GHz Rat-Race Circuit on LiNbO_3 Substrate

    Kunihiro Ryota, Kawai Tadashi, Enokihara Akira, Kawanishi Tetsuya

    Proceedings of the Society Conference of IEICE   2014 ( 1 ) 192 - 192  2014.09

    CiNii

  • Electro-Optic Light Intensity Modulator Integrated with Microwave Rat-Race Circuit

    Yamamoto Masashi, Kawai Tadashi, Enokihara Akira, Kawanishi Tetsuya

    Proceedings of the Society Conference of IEICE   2013 ( 1 ) 246 - 246  2013.09

    CiNii

  • Electro-Optic SSB Modulator Integrated with Miniaturized Branch-Line Coupler Using Interdigital Capacitors

    Yamamoto Katsuyuki, Yamamoto Katsuyuki, Enokihara Akira, Kwanishi Tetsuya

    Proceedings of the Society Conference of IEICE   2013 ( 1 ) 248 - 248  2013.09

    CiNii

  • Influence of harmonic distortion of driving signal on chirp parameter measurement of Mach-Zehnder modulator

    T. Hayashi, H. Toda, T. Kawanishi

    2013 Asia-Pacific Microwave Photonics Conference (APMP 2013)     WB5  2013.04  [Refereed]

  • Investigation of Receiver DSP Carrier Phase Estimation Rate for Self-homodyne Space-division Multiplexing Communication Systems

    DELGADO MENDINUETA, JOSE MANUEL, PUTTNAM BENJAMIN J, SAKAGUCHI JUN, LUIS RUBEN S, KLAUS WERNER, AWAJI YOSHINARI, WADA NAOYA, KANNO ATSUSHI, KAWANISHI TETSUYA

    電気学会電磁界理論研究会資料   EMT-13 ( 1-17.20-59 ) 299 - 302  2013.01  [Refereed]

    J-GLOBAL

  • 光で作る超高速無線信号[後編]—無線伝送技術—

    菅野敦史, 川西哲也

    自動車技術   66 ( 9 ) 100-101  2012.09

    J-GLOBAL

  • Ultra High-speed Wireless Signals Generated by Photonics : Lightwave Modulation

    KAWANISHI Tetsuya, SUGANO Atsushi

      66 ( 7 ) 88 - 89  2012.07

    CiNii

  • Polarization-division-multiplexed 4×10-Gbps simultaneous transmissions in T-band and C-bands over a holey fiber

    OMIGAWA Yu, YAMAMOTO Naokatsu, KANNO Atsushi, KAWANISHI Tetsuya, KURATA Yasuaki, SOTOBAYASHI Hideyuki

    Technical report of IEICE. OFT   111 ( 381 ) 33 - 36  2012.01

     View Summary

    The ever-increasing demand for high data transmission capacities has necessitated the use of alternative wavebands and the development of methods for enhancing the transmission capacities of existing photonic networks. Polarization-division-multiplexing (PDM) and wavelength-division-multiplexing (WDM) are essential techniques for enhancing the capacity of photonic networks and facilitating the efficient use of optical frequency resources. We constructed the ultra-broadband PDM and WDM photonic transport system in the T-band (Thousand-band, 1000〜1260-nm) and C-bands (Conventional-band, 1530〜...

    CiNii

  • Frequency response measurement of half-wave voltage and chirp parameter of LiNbO <inf>3</inf> intensity modulators in low frequency range

    Kimihiro Toki, Dai Uesaka, Takahiro Yamazaki, Hiroyuki Iwata, Masahisa Yoshikawa, Hiroyuki Toda, Tetsuya Kawanishi

    2011 IEEE International Topical Meeting on Microwave Photonics - Jointly Held with the 2011 Asia-Pacific Microwave Photonics Conference, MWP/APMP 2011     354 - 356  2011.12

     View Summary

    We measured frequency responses of half-wave voltage V π and chirp parameter α 0 of LiNbO 3 modulators below 1 GHz range using optical heterodyne scheme with an acousto-optic modulator. The coefficients of variation of the measured values of V π and α 0 are 0.2 % and 2 %, respectively. We observed strong dependency of V π and α 0 on the frequency. © 2011 IEEE.

    DOI

  • W-band High-speed Wireless Transmission using RoF Technology

    KANNO ATSUSHI, KURI TOSHIAKI, HOSAKO IWAO, KAWANISHI TETSUYA, YOSHIDA YUKI, YASUMURA YOSHIHIRO, KITAYAMA KEN'ICHI

    電子情報通信学会技術研究報告   111 ( 338(ED2011 100-118) ) 25-29  2011.12

    J-GLOBAL

  • Parallel Mach-Zehnder modulators for quadrature amplitude modulation

    Tetsuya Kawanishi

    IEICE ELECTRONICS EXPRESS   8 ( 20 ) 1678 - 1688  2011.10

     View Summary

    This paper describes optical quadrature amplitude modulation techniques using parallel Mach-Zehnder modulators (MZMs). Arbitrary constellations of optical signals can be generated by using a dual-parallel MZM which can independently control real and imaginary components of lightwaves, where each MZM should be driven by multi-level electric signals. Many parallel MZMs, such as quad-parallel MZMs, octet-parallel MZMs can synthesize optical multi-level signals from binary data stream generated by electronics designed for binary modulation formats. We also investigate characterization methods of parallel MZMs. Precise measurement of half-wave voltage, extinction ratio and chirp parameter of each MZM element can be achieved by using optical spectrum analysis.

    DOI

  • 20-Gb/s W-band wireless transmission using radio-over-fiber technique

    KANNO Atsushi, INAGAKI Keizo, MOROHASHI Isao, SAKAMOTO Takahide, KURI Toshiaki, HOSAKO Iwao, KAWANISHI Tetsuya, YOSHIDA Yuki, KITAYAMA Ken-ichi

    IEICE technical report   111 ( 150 ) 57 - 60  2011.07

     View Summary

    We demonstrate 20 Gb/s W-band QPSK transmission over the air. Optically synthesized 20 Gb/s QPSK signal with RoF technique is converted to the radio signal using direct optical upconversion technique with a high-speed photodetector. Transmitted W-band radio signal was detected and demodulated with a W-band digital receiver. The observed bit error rates was achieved 10〜6 with a distance of 30 mm.

    CiNii

  • Polarization Division Multiplexed 2×10-Gbps Optical Data Transmissions in T-waveband with Holey Fiber Photonic Transport System

    Omigawa Yu, Kinoshita Yuta, Yamamoto Naokatsu, Kanno Atsushi, Akahane Kouichi, Kawanishi Tetsuya, Sotobayashi Hideyuki

    Technical report of IEICE. OCS   111 ( 122 ) 35 - 38  2011.07

     View Summary

    The ever-growing demand for high data transmission capacities has created a need for the use of alternative wavebands and the development of methods for enhancing the transmission capacities of photonic networks. We recently focused on a use of a 1.0-μm waveband as namely a T-band (Thousand-band) to pioneer ultra-broad optical frequency resources for the optical communications. In this paper, error-free polarization division multiplexed (PDM) 10-Gbps × 2-PDM transmissions over a 3.7-km holey fiber in the T-band is successfully demonstrated for the first time.

    CiNii

  • 16 QAM Generation by Angular Superposition of Polarization Using Polarization-Multiplexing QPSK Modulator

    MOROHASHI ISAO, SAKAMOTO TAKAHIDE, SUDO MASAAKI, KANNO ATSUSHI, CHIBA AKITO, ICHIKAWA JUN'ICHIRO, HOSAKO IWAO, KAWANISHI TETSUYA

    電子情報通信学会技術研究報告   111 ( 122(OCS2011 26-44) ) 63-66  2011.07

    J-GLOBAL

  • Technologies on multi-core fiber and spatial division multiplexing enabling extremcly advanced optical transmission

    SAKAGUCHI JUN, AWAJI YOSHINARI, WADA NAOYA, KANNO ATSUSHI, KAWANISHI TETSUYA, HAYASHI TETSUYA, TARU TOSHIKI, KOBAYASHI TETSUYA, WATANABE MASAYUKI

    電子情報通信学会技術研究報告   111 ( 111(OPE2011 15-27) ) 29-34  2011.06

    J-GLOBAL

  • 高速多値変調デバイス

    菅野敦史, 坂本高秀, 諸橋功, 川西哲也

    応用物理学関係連合講演会講演予稿集(CD−ROM)   58th   ROMBUNNO.25P-KB-4  2011.03

    J-GLOBAL

  • Application of high-speed signal synthesis using precise optical modulation technique

    Optronics   30 ( 3 ) 118 - 122  2011.03

    CiNii

  • Frequency-stabilized W-band two-tone optical signal generation for high-speed RoF and radio transmission

    KANNO Atsushi, INAGAKI Keizo, MOROHASHI Isao, KURI Toshiaki, HOSAKO Iwao, KAWANISHI Tetsuya

    Annu Meet IEEE Photonic Soc   2011   272-273  2011

    DOI J-GLOBAL

  • B-13-46 Estimation of optical frequency resources in 1-μm waveband for photonic transport system

    Omigawa Yu, Kinoshita Yuta, Yamamoto Kazuyuki, Yamamoto Naokatsu, Kanno Atsushi, Akahane Kouichi, Kawanishi Tetsuya, Sotobayashi Hideyuki

    Proceedings of the Society Conference of IEICE   2010 ( 2 )  2010.08

    CiNii

  • Optical Two-tone Generation and SSB Modulation using Electro-optic Modulator and Suppression of Redundant Spectrum Components

    ENOKIHARA Akira, KAWAI Tadashi, KAWANISHI Tetsuya

    IEICE technical report   110 ( 155 ) 51 - 56  2010.07

     View Summary

    Optical two-tone generation and single-side-band (SSB) optical modulation are realized by the dual electrode type electro-optic (EO) modulator with a single Mach-Zehnder (MZ) interferometer. Redundant optical spectrum components of the two-tone waves, which are caused by the imbalance of light splitting ratio in the interferometer, are significantly suppressed by controlling the input power ratio of RF signals applied to each electrode. This effect was confirmed by the experiment, where an optical two-tone with the redundant components 49.8 dB lower than the primary two-tone component level was obtained. In case of the SSB modulation, the redundant sideband suppression ratio was more than 50 dB.

    CiNii

  • 160 Gb/s full-ETDM NRZ-DQPSK modulation by a broadband optical IQ modulator

    KANNO Atsushi, SAKAMOTO Takahide, CHIBA Akito, KAWANISHI Tetsuya, SUDOU Masaaki, HIGUMA Kaoru, ICHIKAWA Junichiro

    Technical report of IEICE. OPE   110 ( 156 ) 37 - 40  2010.07

     View Summary

    160-Gb/s NRZ-DQPSK optical modulation with full-ETDM technique is successfully demonstrated. A development of an optical IQ moduator with novel functions, which are broad bandwidth and low half-wave voltage, can realize ultra-high-speed modulation.

    CiNii

  • Simultaneous transmissions in T-, C-, and L-bands with ultra-broadband photonic transport system

    YAMAMOTO Naokatsu, OMIGAWA Yu, KANNO Atsushi, AKAHANE Kouichi, KAWANISHI Tetsuya, SOTOBAYASHI Hideyuki

    Technical report of IEICE. OCS   110 ( 152 ) 47 - 50  2010.07

     View Summary

    An ultra-broadband photonic transport system has been developed to expand the usable wavelength bandwidth for optical communication. Currently, we have focused on a use of a 1-μm wavelength band as namely a T-band(Thousand-band)to pioneer an ultra-broad optical frequency resources for the optical communications. In this paper, simultaneous 3 × 10-Gb/s error-free photonic transmissions are successfully demonstrated in the T-, C-, and L-bands by using the ultra-broadband photonic transport system over a 5.4-km-long holey fiber transmission line.

    CiNii

  • C-14-2 High-speed chirp signal generation by double sideband-suppressed carrier modulation using MZ LiNbO_3 optical modulator

    Honda Shinnosuke, Kanno Atsushi, Kawanishi Tetsuya, Sotobayashi Hideyuki

    Proceedings of the IEICE General Conference   2010 ( 1 )  2010.03

    CiNii

  • 100 Gbps NRZ-DPSK signal generation using high-speed and low-Vπ LN modulator

    KANNO Atsushi, SAKAMOTO Takahide, CHIBA Akito, KAWANISHI Tetsuya, HIGUMA Kaoru, SUDOU Masaaki, ICHIKAWA Junichiro

    Technical report of IEICE. OCS   109 ( 400 ) 89 - 92  2010.01

     View Summary

    A broadband modulator with a low operation voltage has been developed for ultra-high-speed modulation. We fabricated the high-speed optical LN modulator with 3-dB bandwidth of 25 GHz. Applying a ridge-type optical waveguide structure on a z-cut LN substrate helps realize a Vπ of 1.9 V at a frequency of 25 GHz in differential operation. 100 Gb/s NRZ-DPSK signal generation with the modulator was successfully demonstrated.

    CiNii

  • Measurement of Mach-Zehnder interferometer based modulators by using optical spectrum analysis

    KAWANISHI Tetsuya, SAKAMOTO Takahide, CHIBA Akito, TODA Hiroyuki, ENOKIHARA Akira, MURATA Hiroshi

    IEICE technical report   108 ( 259 ) 53 - 58  2008.10

     View Summary

    We investigated precise measurement methods for half-wavelength voltage, chirp paramter, extinction ratio of Mach-Zehnder modulators. Recently, very high extinction ratio over 70dB and ultra low chirp under 0.01 were achieved by using an active trimming technique. In addtion, precice and high-speed lighwave control or modulation would be very important in advanced modulation formats, such as 256 quadrature amplitude modulation.

    CiNii

  • C-3-64 Quadruple RF generation using a high extinction-ratio optical modulator and a delayed interferometer

    Toda Hiroyuki, Miyashita Junichi, Kiuchi Hitoshi, Chiba Akito, Sakamoto Takahide, Kawanishi Tetsuya, Tsuchiya Masahiro, Izutsu Masayuki

    Proceedings of the IEICE General Conference   2008 ( 1 )  2008.03

    CiNii

  • B-4-5 Phase Imaging of Transmitted Microwave by High-Resolution Electric Near-Field Camera

    Kanno Atsushi, Sasagawa Kiyotaka, Kawanishi Tetsuya, Tsuchiya Masahiro

    Proceedings of the IEICE General Conference   2007 ( 1 )  2007.03

    CiNii

  • Phase Stability Measurement of an Optical Two-Tone Signal Applied to a Signal Reference Source for Millimeter and Sub-Millimeter Wave Interferometer

    YAMADA Masumi M., KIUCHI Hitoshi, KAWANISHI Tetsuya, SAKAMOTO Takahide, TSUCHIYA Masahiro, AMAGAI Jun, IZUTSU Masayuki

    Publications of the Astronomical Society of Japan   58 ( 4 ) 787 - 791  2006.08

    CiNii

  • Frequency-Modulation characteristics of Resonant-Electrode-Type Optoelectronic Oscillator

    SAKAMOTO Takahide, KAWANISHI Tetsuya, IZUTSU Masayuki

      2006 ( 47 ) 131 - 135  2006.07

    CiNii

  • Ultra-flat otpical frequency comb generation using Mach-Zehnder modulator

    SAKAMOTO Takahide, KAWANISHI Tetsuya, IZUTSU Masayuki

    IEICE technical report   105 ( 382 ) 49 - 53  2005.11

     View Summary

    Driving LiNbO_3 modulator with large-amplitude signal, optical frequency comb is generated with excellent stabilty. Conventionally, at least two optial modulators are required to generate flequency comb signal with good spectral flattness. We propose and demonstrate optical frequency comb generation with good spectral flatness, using a conventional Mach-Zehnder modulator asymmetrically dual-driven by large-amplitude sinusoidal signals with different amplitudes. 120-GHz bandwidth, 10-GHz spacing frequency comb was experimentally generated.

    CiNii

  • 40Gbit/s Versatile LiNbO3 External Lightwave Modulator

    KAWANISHI Tetsuya, HIGUMA Kaoru, FUJITA Takahisa, MORI Shingo, OIKAWA Satoshi, ICHIKAWA Junichiro, SAKAMOTO Takahide, TSUCHIYA Masahiro, IZUTSU Masayuki

    IEICE technical report   105 ( 382 ) 45 - 48  2005.11

     View Summary

    We propose a high-speed versatile lightwave modulator which can generate on-off-keying, phase-shift-keying and frequency-shift-keying signals. 40Gbit/s optical FSK modulation was demonstrated by using the modulator consisting of six phase modulators, where frequency deviation was 80GHz. By using this versatile modulator, we can also generate lightwave signals of various modulation formats, such as QPSK, CSRZ-OOK, etc.

    CiNii

  • Wavelength tunable optical frequency comb generation using phase-modulator-type photoelectronic oscillator

    SAKAMOTO Takahide, KAWANISHI Tetsuya, IZUTSU Masayuki

    Technical report of IEICE. OPE   105 ( 183 ) 25 - 29  2005.07

     View Summary

    Previously, we proposed a novel optoelectronic oscillator for frequency comb generation. The oscillater consists of a phase modulator, a fiber bragg grating (FBG) and a photodetector. The phase-modulated signal is asymmetrically filtered by the FBG then fed back to a modulation electrode. The amplitude of the feed-back signal is large enough to generate its harmonics. In this report, we improve the frequency comb generator for wavelength tunable operation, by using a tunable FBG whose Bragg wavelength is controlled with respect to the wavelenght shift of the pump lightwave. More than 10-nm wavelength tuning was confirmed for self-oscillating optical frequency comb generation.

    CiNii

  • 60GHz-band ROF transmitter with Reciprocating Optical Modulator

    SHIMAKURA Yasuhisa, YOSHIARA Kiichi, SAKAMOTO Takahide, SHINADA Satoshi, KAWANISHI Tetsuya

    Technical report of IEICE. OPE   105 ( 183 ) 13 - 18  2005.07

     View Summary

    The reciprocating optical modulator (ROM) which is consisted of two optical filters and an optical modulator is expected to realize low cost radio-on-fiber system in millimeter-wave-band. The ROM can be driven by low frequencies. In this paper, we have reported the design of ROM and the trial manufactured 60GHz-band ROF transmitter. We have successfully demonstrated to generate the millimeter-wave (frequency : 60.05GHz, rf power : +10dBm) by reciprocating 4.289286GHz rf signal source. Also, it was also shown that the high speed data transmission up to 3Gbps by the ASK modulation is possible.

    CiNii

  • Optoelectronic Oscillation using Optical Phase Modulator for Frequency Comb Generation

    SAKAMOTO Takahide, KAWANISHI Tetsuya, IZUTSU Masayuki

    Technical report of IEICE. OPE   104 ( 333 ) 5 - 9  2004.10

     View Summary

    We propose a novel optoelectronic oscillator for frequency comb generation. The oscillator consists of a phase modulator, a fiber bragg grating (FBG) and a photodetector. The phase-modulated signal is asymmetrically filtered by the FBG then fed back to a modulation electrode. The amplitude of the feed-back signal is large enough to generate its harmonics. By self-oscillating operation of the photoelectronic oscillator, optical frequency comb signal is generated.

    CiNii

  • Simultaneous optical modulation of FSK and IM

    KAWANISHI Tetsuya, SAKAMOTO Takahide, SHINADA Satoshi, FUJITA Takahisa, HIGUMA Kaoru, ICHIKAWA Junichiro, IZUTSU Masayuki

    Technical report of IEICE. LQE   104 ( 270 ) 41 - 46  2004.08

     View Summary

    We investigate simultaneous optical modulation of frequency-shift-keying (FSK) and inten-sity-modulation (IM). The FSK/IM signal can be generated by using an optical FSK modulator, which is based on an optical single-sideband modulator consisting of two Mach-Zehnder interferometers. The FSK modulator outputs one of the sideband components generated in the interferometers. The FSK switching speed was faster than 100 ps.

    CiNii

  • Reciprocating Optical Modulator for Millimeter-Wave-Band Amplitude-Shift-Keyed Radio-on-Fiber Signal Genaration and its Characteristics

    SAKAMOTO Takahide, KAWANISHI Tetsuya, SHINADA Satoshi, IZUTSU Masayuki

    Technical report of IEICE. LQE   103 ( 619 ) 13 - 18  2004.01

     View Summary

    A reciprocating optical modulator (ROM) generates higher order harmonics in good efficeincy and in high stability. We propose two novel methods for amplitude-shift-keyed modulated radio-on-fiber (ASK-ROF) signal generation using ROM; external and internal modulation schemes. Especially, internal modulation greatly reduces driving voltage for baseband signal due to reciprocating modulation process. In this paper, 52.8-GHz ASK-ROF signal generation is demonstrated with low-voltage (2.0 V) base-band signal, where V_πwas 6.4 V. The upper limit of the internal modulation speed is also evaluated.

    CiNii

  • Two beam collection mode photon scanning tunneling microscope

    Tetsuya Kawanishi, Kouichiro Tamada, Masao Kitano

    Optical Review   4 ( 5 ) 601 - 604  1997

     View Summary

    We studied the image deformation due to the surface inclination of objects in photon scanning tunneling microscopes (PSTM). A novel collection mode PSTM with two light sources is proposed to reduce the deformation and experimental results show that the PSTM system is effective.

    DOI

  • Scattering of electromagnetic wave from -----

    Waves in Random media 7 351-384  

    DOI

  • Conjugate memory effect of random Acattered waves

    JOSA 16 1342-1349  

  • Brewster's scattering angle and quasi-anomalous scattering in random scattering from dieleatric interfaces

    JOSA 16 339-342  

  • Two beam collection mode photon scanning tunneling microscope

    Waves in Random media 7 351-384  

  • Scattering of electromagnetic wave from -----

    Waves in Random media 7 351-384  

    DOI

  • Conjugate memory effect of random Acattered waves

    JOSA 16 1342-1349  

  • Brewster's scattering angle and quasi-anomalous scattering in random scattering from dieleatric interfaces

    JOSA 16 339-342  

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    特許第4631006号

    川西 哲也, 坂本 高秀, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • Y接合反射器による調整可能遅延または共振器導波路装置

    特許第4635050号

    チェン,ジアンクシアオ, ユ,ポール,キット,ライ, 川西 哲也, 日隈 薫

    Patent

    J-GLOBAL

  • RZ-FSK変調器及びUWB信号の発生装置

    特許第4604162号

    坂本高秀, 川西哲也, 井筒雅之

    Patent

    J-GLOBAL

  • 可変分散補償装置

    特許第4590626号

    川西 哲也, 井筒 雅之, セット・ジ・イヨン, マーク・ジャボロンスキー, 田中 佑一

    Patent

    J-GLOBAL

  • 光信号波長変換方法および光信号波長変換装置

    千葉 明人, 坂本 高秀, 川西 哲也

    Patent

    J-GLOBAL

  • バイアス点調整機能を有する光変調器及びスイッチ

    千葉 明人, 坂本 高秀, 川西 哲也

    Patent

    J-GLOBAL

  • 光位相変調と光FSK変調を用いた光波長多重FSK変調システム

    特許第4555978号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 高次成分を消去可能な光振幅変調システム

    特許第4552032号

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • キャリアや2次成分を消去可能なDSB-SC変調システム

    特許第4547552号

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 周波数シフトキーイング復調器

    特許第4533999号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光SSB変調器

    特許第4524482号

    川西 哲也, 井筒 雅之, 日隈 薫, 森 慎吾

    Patent

    J-GLOBAL

  • 多波長光源

    特許第4484021号

    黒川 隆志, 日隈 薫, 市川 潤一郎, 井筒 雅之, 川西 哲也

    Patent

    J-GLOBAL

  • 位相制御光FSK変調器

    特許第4465458号

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • ファイバ無線用ユニット及びファイバ無線用システム

    品田 聡, 川西 哲也, 中島 慎也

    Patent

    J-GLOBAL

  • 多波長信号発生装置,及び多波長光の発生方法

    特許第4423372号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 複数マッハツェンダー干渉計を有する光変調器の特性評価方法

    川西 哲也, 中島 慎也, 品田 聡

    Patent

    J-GLOBAL

  • 高精度マッハツェンダー干渉計を有する光変調器の特性評価方法

    川西 哲也, 中島 慎也, 品田 聡

    Patent

    J-GLOBAL

  • 光QAM信号の復調方法,及び復調装置

    千葉 明人, 坂本 高秀, 川西 哲也, 土屋 昌弘

    Patent

    J-GLOBAL

  • 超平坦光周波数コム信号発生器

    坂本 高秀, 川西 哲也, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • 時間分解分光システム,時間分解分光方法及びテラヘルツ波発生システム

    諸橋 功, 坂本 高秀, 寳迫 巌, 川西 哲也, 関根 徳彦, 齋藤 伸吾, 土屋 昌弘

    Patent

    J-GLOBAL

  • 光干渉トモグラフィー装置,光形状計測装置

    川西 哲也, 坂本 高秀, 山本 剛裕, 千葉 明人, 土屋 昌弘

    Patent

    J-GLOBAL

  • 情報配信システム

    川西 哲也, 土屋 昌弘

    Patent

    J-GLOBAL

  • 高光閉じ込め導波路インターサブバンド全光スイッチ

    牛頭 信一郎, カトフ レドワン, 山本 直克, 赤羽 浩一, 上田 章雄, 川西 哲也, 土屋 昌弘

    Patent

    J-GLOBAL

  • ネスト型変調器

    市川 潤一郎, 日隈 薫, 山本 太, 及川 哲, 森 慎吾, 栗村 直, 北村 健二, 川西 哲也, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • 位相変調変換によるバイアス制御不要強度変調器

    品田 聡, 川西 哲也

    Patent

    J-GLOBAL

  • 高速逓倍信号発生方法及び装置

    川西 哲也, 坂本 高秀, 土屋 昌弘

    Patent

    J-GLOBAL

  • Y接合反射器による調整可能遅延または共振器導波路装置

    チェン,ジアンクシアオ, ユ,ポール,キット,ライ, 川西 哲也, 日隈 薫

    Patent

    J-GLOBAL

  • 超高速光周波数掃引技術

    川西 哲也, 坂本 高秀, 土屋 昌弘

    Patent

    J-GLOBAL

  • 低雑音光周波数変換装置

    特許第4041882号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 超平坦光周波数コム信号発生器

    坂本 高秀, 川西 哲也, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 光干渉による光スイッチシステム

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 光強度測定器のキャリブレーション方法及び装置

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 多波長光源,及び多波長光の発生方法

    特許第3937233号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光周波数シフトキーイング変調器

    特許第3937237号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 位相制御光FSK変調器

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 往復逓倍光変調器

    特許第3931235号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • キャリアや2次成分を消去可能なDSB-SC変調システム

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 高次成分を消去可能な光振幅変調システム

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 強度バランス機能を有する光FSK/SSB変調器

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • FSK変調器の自動調整システム

    川西 哲也, 坂本 高秀, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • 往復逓倍変調システム

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 高消光比変調可能な光搬送波抑圧両側波帯(DSB-SC)変調システム

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 光搬送波抑圧両側波帯変調器を用いた4倍波発生システム

    川西 哲也, 坂本 高秀, 井筒 雅之, 土屋 昌弘

    Patent

    J-GLOBAL

  • 光変調装置およびそれを用いた光信号と電波信号との変換装置

    特許第3913547号

    川西 哲也, 井筒 雅之, 及川 哲, 日隈 薫

    Patent

    J-GLOBAL

  • 光線制御装置及びそれを用いた立体像表示装置

    川西 哲也, 品田 聡, 土屋 昌弘

    Patent

    J-GLOBAL

  • 位相連続光周波数偏移変調器、位相連続光周波数偏移変調方法

    坂本 高秀, 川西 哲也, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • 変調光信号発生装置,及びFSK変調信号発生装置

    特許第3874119号

    川西 哲也, 原田 博司, 井筒 雅之

    Patent

    J-GLOBAL

  • 進行波型電極用の駆動回路、それを用いた光変調システム、光情報通信システム及び進行波型電極用の駆動方法

    川西 哲也, 坂本 高秀, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • 光SSB変調器又は光FSK変調器のバイアス調整方法

    特許第3867148号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光変調器の特性測定方法及び装置

    特許第3866082号

    及川 哲, 井筒 雅之, 日隈 薫, 川西 哲也

    Patent

    J-GLOBAL

  • 光位相変調と光FSK変調を用いた光波長多重FSK変調システム

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光電気発振器及び光電気発振方法

    坂本 高秀, 川西 哲也, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • 光強度変調と光周波数シフトキーイング変調システム

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 位相連続光FSK変調方法,位相連続光FSK変調器

    坂本 高秀, 川西 哲也, 宮崎 哲弥, 井筒 雅之

    Patent

    J-GLOBAL

  • 光電気発振器及び光電気発振方法

    川西 哲也, 坂本 高秀, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • 低雑音光周波数変換装置

    特許第3851949号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 超高消光比変調方法

    川西 哲也, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • 光波長多重FSK変調方法

    特許第3843322号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 共振電極構造を有する光変調器を用いた光電気発振器

    特許第3831787号

    川西 哲也, 井筒 雅之, 坂本 高秀

    Patent

    J-GLOBAL

  • 光通信システム

    川西 哲也, 坂本 高秀, 土屋 昌弘, 井筒 雅之

    Patent

    J-GLOBAL

  • RZ-FSK変調器及びUWB信号の発生装置

    坂本高秀, 川西哲也, 井筒雅之

    Patent

    J-GLOBAL

  • 周波数シフトキーイング復調器

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 多波長信号発生装置,及び多波長光の発生方法

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 変調光信号発生装置,及びFSK変調信号発生装置

    川西 哲也, 原田 博司, 井筒 雅之

    Patent

    J-GLOBAL

  • 多波長光源,及び多波長光の発生方法

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光電気発振器

    川西 哲也, 井筒 雅之, 坂本 高秀, 品田 聡

    Patent

    J-GLOBAL

  • 可変光遅延装置

    特許第3747241号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 多波長一括光変調方法および多波長一括光変調器

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 可変分散補償装置

    川西 哲也, 井筒 雅之, セット・ジ・イヨン, マーク・ジャボロンスキー, 田中 佑一

    Patent

    J-GLOBAL

  • 光SSB変調器

    川西 哲也, 井筒 雅之, 日隈 薫, 森 慎吾

    Patent

    J-GLOBAL

  • 光SSB変調器又は光FSK変調器のバイアス調整方法

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 短光パルス発生器

    津田 裕之, 黒川 隆志, 川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 共振電極構造を有する光変調器を用いた光電気発振器

    川西 哲也, 井筒 雅之, 坂本 高秀

    Patent

    J-GLOBAL

  • 光波長多重FSK変調方法

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光FSK変調器を用いたUWB信号の発生装置

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 非対称電極を用いた共振型半導体光変調器

    特許第3699997号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光周波数シフトキーイング変調器

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 3次元電界分布測定方法および3次元電界分布測定装置

    特許第3660997号

    川西 哲也, 松尾 善郎, 井筒 雅之

    Patent

    J-GLOBAL

  • 多波長光源

    黒川 隆志, 日隈 薫, 市川 潤一郎, 井筒 雅之, 川西 哲也

    Patent

    J-GLOBAL

  • 往復逓倍光変調器

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 共振型光変調器

    特許第3592245号

    川西 哲也, 井筒 雅之, 久保寺 憲一

    Patent

    J-GLOBAL

  • 集積型光逓倍変調装置

    特許第3577508号

    川西 哲也

    Patent

    J-GLOBAL

  • 3次元電界分布測定方法および3次元電界分布測定装置

    川西 哲也, 松尾 善郎, 井筒 雅之

    Patent

    J-GLOBAL

  • 光変調器の特性評価方法、およびそれを用いた高周波発振装置の制御方法

    特許第3538619号

    川西 哲也

    Patent

    J-GLOBAL

  • 低雑音光周波数変換装置

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 低雑音光周波数変換装置

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光周波数変換装置

    特許第3516032号

    川西 哲也

    Patent

    J-GLOBAL

  • 集積型光周波数変換装置

    特許第3496053号

    川西 哲也

    Patent

    J-GLOBAL

  • 非対称電極を用いた共振型半導体光変調器

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 可変光遅延装置

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光変調装置およびそれを用いた光信号と電波信号との変換装置

    川西 哲也, 井筒 雅之, 及川 哲, 日隈 薫

    Patent

    J-GLOBAL

  • 光変調器の特性測定方法及び装置

    及川 哲, 井筒 雅之, 日隈 薫, 川西 哲也

    Patent

    J-GLOBAL

  • 逓倍変調による光周波数変換装置

    特許第3404528号

    川西 哲也

    Patent

    J-GLOBAL

  • 電磁波のフィルタ管路

    堀 利浩, 川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 光周波数変換装置

    川西 哲也

    Patent

    J-GLOBAL

  • 非対称電極を用いた共振型光変調器

    川西 哲也, 井筒 雅之, 久保寺 憲一

    Patent

    J-GLOBAL

  • 共振型光変調器

    川西 哲也, 井筒 雅之, 久保寺 憲一

    Patent

    J-GLOBAL

  • 評価面の粗さ測定方法および評価面の粗さ測定装置

    特許第3348198号

    川西 哲也

    Patent

    J-GLOBAL

  • 光変調器の特性評価方法、およびそれを用いた高周波発振装置の制御方法

    川西 哲也

    Patent

    J-GLOBAL

  • 逓倍光変調装置

    特許第3343241号

    川西 哲也

    Patent

    J-GLOBAL

  • 集積型光周波数変換装置

    川西 哲也

    Patent

    J-GLOBAL

  • 集積型光逓倍変調装置

    川西 哲也

    Patent

    J-GLOBAL

  • 共振型光変調器の光変調方法及び共振型光変調器

    井筒 雅之, 及川 哲, 宮崎 徳一, 川西 哲也

    Patent

    J-GLOBAL

  • アンテナ装置

    特許第3281917号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 逓倍変調による光周波数変換装置

    川西 哲也

    Patent

    J-GLOBAL

  • 逓倍光変調装置

    川西 哲也

    Patent

    J-GLOBAL

  • 非接触表面粗さ評価方法および非接触表面粗さ評価装置

    特許第3243525号

    川西 哲也

    Patent

    J-GLOBAL

  • 同軸周期構造光導波路およびそれを用いた光フィルタ

    川西 哲也

    Patent

    J-GLOBAL

  • フォトニックバンドギャップ構造を用いた光変調器及び光変調方法

    特許第3200629号

    川西 哲也

    Patent

    J-GLOBAL

  • 評価面の粗さ測定方法および評価面の粗さ測定装置

    川西 哲也

    Patent

    J-GLOBAL

  • フォトニックバンドギャップ構造を用いた光変調器及び光変調方法

    川西 哲也

    Patent

    J-GLOBAL

  • アンテナ装置

    川西 哲也

    Patent

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  • 非接触表面粗さ評価方法および非接触表面粗さ評価装置

    川西 哲也

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  • 波長変換装置

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 波長変換装置

    川西 哲也, デバシス・ドーン, 井筒 雅之

    Patent

    J-GLOBAL

  • 波長変換装置

    特許第3062750号

    川西 哲也, 井筒 雅之

    Patent

    J-GLOBAL

  • 非接触面粗さ評価方法および非接触面粗さ評価装置

    川西 哲也

    Patent

    J-GLOBAL

  • 非接触面粗さ評価方法および非接触面粗さ評価装置

    特許第3010213号

    川西 哲也

    Patent

    J-GLOBAL

  • 散乱光を用いた光学部品検査装置

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  • 2つの光源を用いた透過型光走査トンネル顕微鏡

    川西 哲也

    Patent

    J-GLOBAL

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Overseas Activities

  • 光無線融合デバイスに関する研究

    2021.10
    -
    2022.03

    タイ   チェンマイ大学

Sub-affiliation

  • Faculty of Science and Engineering   Graduate School of Fundamental Science and Engineering

Research Institute

  • 2023
    -
    2027

    Institute of Radio Photonics for 6G Network   Director of Research Institute

  • 2022
    -
    2024

    Waseda Research Institute for Science and Engineering   Concurrent Researcher

  • 2022
    -
    2024

    Global Information and Telecommunication Institute   Concurrent Researcher

Internal Special Research Projects

  • マルチフィジックスアンテナ設計技術

    2023  

     View Summary

    無線通信においてアンテナは必須のデバイスであり、その特性評価は回線設計のみならず、他のアプリケーションとの共存のためにも重要である。これまで無線通信に用いられてきたマイクロ波帯においてアンテナは、定常的に設置・固定されたものとして扱い、純粋な電磁気学的特性のみに着目した評価で十分であった。これは、マイクロ波帯の波長は長く(たとえば5Gで用いられている6 GHz程度であってもその波長は5 cm)、アンテナの力学的偏位が電磁気学的特性に与える影響が無視できたからである。ところが、Beyond5G/6G時代での活用が期待される100 GHz以上のテラヘルツ波帯は、その波長がマイクロ波帯と比べて一桁以上短くなることから必然的に指向性が高まり、その狭いビーム広がり角に対してアンテナの力学的偏位量が無視できない領域となる。これまで我々の研究グループでは、風雨がテラヘルツ通信にあたえる影響について報告してきたが、本研究ではマルチフィジックス問題としての基礎検討を進めた。降雨は電波の散乱や吸収を引き起こす。風はアンテナの振動を発生させる。これに加えて、降雪や温度変化の影響も考慮に入れる必要がある。このような総合的なマルチフィジックスの重要性をアンテナのみならず、光ファイバ通信へも適用し、共通したコンセプトで解析を進めるスキームを構築した。これをもとに、日独の国際共同研究の体制を整えた。

  • 高速高安定広帯域周波数掃引光源に関する研究

    2022  

     View Summary

    時間的に変動する干渉を含む伝送システムにおいて、本来の伝送能力を極限まで引き出すためには、広帯域周波数特性の高速測定が重要な役割を果たす。本研究では高速測定のための周波数掃引光源に関する基礎検討を行った。高精度光変調器に周波数掃引電気信号を入力すると、周波数掃引光信号が得られるが、その強度は、電気回路、光変調器の周波数特性の影響を受けて大きく変動する。この変動を可変光減衰器で調整し、一定のレベルとすることで計測用の基準信号源となる。一般に可変幅の大きな光減衰器は機械的な駆動部を有しておりその動作速度に限界がある。本研究ではナノ秒オーダーで動作する電気光学効果を用いた可変減衰器を利用した。

  • 非対称スペクトル光変調を用いた高速周波数測定

    2022  

     View Summary

    無線通信のさらなる高速化やレーダなどのセンシングのさらなる高性能化を目的として、帯域幅が数GHzを超えるようなシステムの開発が進められている。その中で周波数チャープ信号や周波数ホッピングなどの周波数が大幅かつ高速に変化する信号の利用が広まりつつある。本研究では2つの電気入力を持つ光変調器を用いた周波数測定技術の開発に取り組んだ。光変調器の出力光スペクトルは2つの電気入力の位相差に依存する。特に90度位相差の際に最も非対称なスペクトルになる。この非対称性を簡便な光検出器で測定し、周波数を算出するという原理である。これまでに原理確認は完了していたが、今年度、測定範囲の拡大、精度の向上を進めた。

  • テラヘルツ波のランダム表面散乱についての研究

    2021   稲垣惠三, 吉野理玖

     View Summary

    Beyond 5Gや6Gではさらなる高速伝送を実現するためにテラヘルツ帯・ミリ波帯の活用が積極的に検討されている。このような周波数帯では、波長が1ミリメートル以下となり、身の回りの平坦に見えるものがもつ微小な凹凸による散乱が問題となり得る。本研究では身近なものによるテラヘルツ波の散乱・反射特性を把握することを目的として、建材などを想定した表面からのテラヘルツ波散乱のモデル化と基礎実験を行った。散乱波は直接反射波に比べると微小であるので、金属による反射の影響を防ぐために、木材とプラスティックで実験装置を組み、75-110GHzの周波数帯における散乱測定を行った。理論予測と同等の散乱波の実測に成功した。

  • 高速周波数掃引による光・電波環境の瞬時測定

    2021  

     View Summary

    時間的に変動する干渉を含む伝送システムにおいて、本来の伝送能力を極限まで引き出すためには、広帯域周波数特性の高速測定が重要な役割を果たす。本研究では信号源の変動の影響も詳細に検討し、測定装置としての精度の技術限界を明らかにすることを目的とした。今年度は現在注目を集めているテラヘルツ・ミリ波帯において、周波数掃引信号による伝搬特性測定を行った。また、レーダーとして動作した際の基本特性を30GHz, 60GHz, 90GHzで測定し、理論通りレーダー測距性能が周波数によらず、帯域幅のみに依存することを2GHzを超える広帯域信号で確認した。

  • 高速デジタル信号処理を用いた歩行者保護のための2次レーダーシステムに関する研究

    2020  

     View Summary

     本研究では従来のセンシング技術の普及では対応が困難であった見通し外の対象物を検知するレーダシステムに関する研究を行う。交通弱者である歩行者を低コストで検知するシステムの実現が目標である。歩行者の存在を知らせる信号が散乱の影響を受けても識別できる必要があるため、2次レーダ方式の適用を検討している。応答装置は歩行者が携帯できる程度に簡易構造であり、かつ高速応答が可能であることが必須である。限られた電波帯域で高い検知性能の実現を目指すため、オーバーサンプリング技術に着目した。本研究では電波伝搬、レーダ信号処理のシミュレーションを実施し、その結果、2m程度の測位誤差で対象物検知の可能性が示唆された。

  • 光伝搬遅延とデータ通信需要の関係の探求

    2020   稲垣惠三, 実野邦久

     View Summary

     本研究の最終的な目的は、光速が有限であり、当面、人類が地球上で生活するということを前提とした場合の、シーズとしての伝送技術における低遅延化の限界を理論、実験の両面から求め、一定の遅延が不可避であるという条件下でのニーズとしての情報通信需要の上限を探ることである。フィージビリティスタディとしていくつかのユースケースを取り上げ、低遅延システムの構成を検討し、これらの優位性を実証するための実験構成を提案した。具体的には工場内のロボットなど遅延に敏感なアプリケーションのための無線・有線融合システムによる伝送システムについて、無線区間、有線区間を統合的に最適化した回線設計、干渉検討などを行った。

  • 超低遅延情報通信ネットワークの物理限界に関する研究

    2019  

     View Summary

    本研究の目的は、電磁波の伝搬速度が有限であり、シーズとしての伝送技術・センシング技術における低遅延化、高性能化の限界を理論、実験の両面から求めることである。レーダーなどのセンシングでは電磁波の伝搬速度を積極的に活用しているが、送受信機における信号処理遅延が性能を律速する可能性がある。今年度、歩行者保護のためのレーダーシステムの基礎研究を進め、歩行者に簡便な発振器をもたせる構成の有用性を実証した。極限まで処理遅延を押さえるための歩行者側装置を提案し、既存のミリ波レーダー等と組み合わせることで、壁の背後にいる歩行者を検知できる可能性を示した。

  • マイクロ波・ミリ波同時利用レーダー技術の研究

    2018   菅野敦史, 稲垣惠三

     View Summary

     本研究の目的は、見通し外の障害物を検知するためのレーダーの実現である。現在、交通事故の抑止、さらには自動運転の実現を目指して、自動車の周辺状況をセンシングするための技術開発が精力的に行われている。カメラやミリ波レーダーを用いた低コストで有効な衝突防止システムが実現しつつある。しかし、これらのすべてが見通し内の障害物に対するものであり、見通しがきかないところの状況を把握するための技術の開発例は少なく、研究開発の難易度も高い。交差点などにレーダーを設置し、見通し外の障害物を自動車などに通知するシステムの開発も進められているが、狭隘な路地すべてに複雑なシステムを整備するのは困難である。 そこで本研究では、比較的低い周波数の電波で視野外障害物を検知するとともに、現在すでに各社が開発し実用が進むミリ波レーダーやカメラによる視野内検知技術を組み合わせる方式を提案している。今年度はマイクロ波帯2次レーダーの基本原理と見通し外の障害物検知能力の確認を行った。

  • 高調波光変調によるミリ波・テラヘルツ波の高精度周波数制御と並列信号処理への応用

    2017  

     View Summary

    光変調器の非線形性を用いた高調波発生による周波数逓倍は低雑音であることが知られており、ミリ波、THz信号発生に適している。本研究ではこれに周波数掃引、周波数切り替えの機能を持たせることを目標とした。高調波成分の生成効率を重視した従来の手法では一定周波数が前提であったが、掃引と同期した変調器制御により、広帯域光周波数掃引信号発生を目指した。ミリ波帯レーダなどへの応用を想定して、掃引の高速性、周波数の安定度の両立を目指した基本設計を行った。また、周波数切り替えによるスペクトル制御とマルチコアファイバを組み合わせた空間的光信号処理を提案し、並列的演算システムの構成を検討した。

  • 光伝搬遅延とデータ通信需要の関係の探求

    2017  

     View Summary

     本研究の目的は、光速が有限であり、当面、人類が地球上で生活するということを前提とした場合の、シーズとしての伝送技術における低遅延化の限界を理論、実験の両面から求め、一定の遅延が不可避であるという条件下でのニーズとしての情報通信需要の上限を探ることである。情報伝達は光速を越えることは不可能であるので、太平洋横断光ファイバーケーブルなどの長距離伝送を介したネットワーク上ではオンラインゲームなどの即時性を要求するアプリケーションでは大きな影響を生じる。この理論上の絶対限界に近づくための光ファイバシステムの構成と、理論限界を超えるためのアプリケーション上の工夫について基礎検討を行っている。

  • 高調波光変調を用いたミリ波・テラヘルツ帯高安定広帯域掃引信号発生

    2016  

     View Summary

    本研究課題の目標は高精度な光変調を用いてミリ波・テラヘルツ波を生成し、その周波数を広い帯域にわたって変化させる技術の確立である。 周波数掃引信号は高精度FMCWレーダーを実現するための重要な要素技術である。中間周波数帯で精度の高い周波数掃引信号発生技術の開発し、特に、同時に発生する複数の信号の取り扱いについて詳細の検討を行った。複数のFMCWレーダー間で発生しうる干渉について検討し、掃引時間を制御することで、不要なノイズ発生を抑えることが可能であることを示した。本研究課題では中間周波数帯における原理確認を行ったが、今後はミリ波帯信号を用いた実証実験の準備に取りかかる予定である。 

  • 往復逓倍変調による広帯域周波数掃引信号発生

    2015  

     View Summary

     本研究課題の目標は往復逓倍変調による光領域におけるミリ波・テラヘルツ波を生成し、その周波数を広い帯域にわたって変化させる技術の確立である。 往復逓倍変調はデバイス内で有限回光を往復させることで低い周波数の入力信号から高い周波数成分の生成(逓倍)を可能とする。低位相雑音のミリ波、THz信号発生に適している。本研究ではこれに周波数掃引の機能を持たせることを目標とする。往復させるという原理のためこれまでは一定周波数が前提であったが、掃引と同期した変調器制御により、広帯域光周波数掃引信号発生を目指す。今年度は周波数可変の基本原理の検討と、他の基準信号発生方式との比較を行った。&nbsp;

  • 高精度光干渉デバイスによる通信・センシング両用技術に関する研究

    2015  

     View Summary

     本研究課題は、高消光比光干渉計をアクティブトリミング技術により実現し、通信用のデバイスとしての性能向上を実現するとともに動作モードを切り替えることで温度、圧力などの環境変化をモニタするためのセンシングデバイスとしての機能を持たせることを目指すものである。消光比は干渉計のバランスの高さを表す指標である。MZ干渉計を変調器として用いる際には信号発生の精度の高さを表す。センサーとして用いる場合には、感度の高さに相当する。今年度は達成可能な消光比の見積もりと、検出可能な光路変化についての基本的な関係の検討を行った。

  • 高精度光干渉デバイスによる通信・センシング両用技術に関する研究

    2015  

     View Summary

     本研究課題は、超高消光比光干渉計をアクティブトリミング技術により実現し、集積デバイスとしての世界最高水準の精度の達成を目標としている。アクティブトリミングは導波路型MZ干渉計(マッハツェンダー型干渉計)の各アームに強度誤差を補正するための強度トリマーを持つ集積デバイスで実現される。強度トリマー自体もMZ干渉計で構成することが可能で、この場合既存の光変調デバイス作製プロセスが利用でき、実用性が高いが、トリミング用のバイアス電圧とメインのMZ干渉計のバイアス電圧を高精度に制御することが重要である。今年度はバイアス電圧制御アルゴリズム検討に注力し、動作の安定性と精度の高さの両立に適した制御方法を見出した。

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