Updated on 2022/08/17

写真a

 
TAKAHATA, Kiyoto
 
Affiliation
Faculty of Science and Engineering, Graduate School of Information, Production, and Systems
Job title
Associate Professor

Concurrent Post

  • Faculty of Science and Engineering   School of Fundamental Science and Engineering

Research Institute

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

 

Research Areas

  • Electron device and electronic equipment

Research Interests

  • Silicon Photonics

  • Microwave Photonics

  • Optical Interconnection

  • Optical Semiconductor Devices

  • Opto-electronic Integration

Papers

  • Over-67-GHz-bandwidth Membrane InGaAlAs EADFB Laser on Si Platform

    Tatsurou Hiraki, Takuma Aihara, Yoshiho Maeda, Takuro Fujii, Tomonari Sato, Tai Tsuchizawa, Kiyoto Takahata, Takaaki Kakitsuka, Shinji Matsuo

    Optical Fiber Communication Conference (OFC) 2022   M3D.2  2022.03  [Refereed]

     View Summary

    A membrane InGaAlAs electro-absorption modulator with an over 67-GHz bandwidth is integrated with a DFB laser on a Si platform. The integrated device shows a dynamic extinction ratio of 3.8 dB for 100-Gbit/s non-return-to-zero signals.

    DOI

  • Membrane InP-based Modulator and Laser on Si

    Tatsurou Hiraki, Takuma Aihara, Takuro Fujii, Koji Takeda, Yoshiho Maeda, Tai Tsuchizawa, Takaaki Kakitsuka, Kiyoto Takahata, Shinji Matsuo

    2021 IEEE 17th International Conference on Group IV Photonics (GFP)   WA2  2021.12

    DOI

  • 60-GHz-bandwidth O-band Membrane InGaAlAs Electro-Absorption Modulator on Si Platform

    Takuma Aihara, Tatsurou Hiraki, Yoshiho Maeda, Takuro Fujii, Tai Tsuchizawa, Kiyoto Takahata, Takaaki Kakitsuka, Shinji Matsuo

    2021 IEEE 17th International Conference on Group IV Photonics (GFP)   WA1  2021.12  [Refereed]

     View Summary

    We demonstrate a 60-GHz-bandwidth O-band electro-absorption modulator (EAM) on a Si photonics platform. The EAM consists of an InGaAlAs multiple quantum well with a lateral p-i-n junction, and is fabricated by heterogeneous integration technique. Clear eye opening for 100-Gbit/s non-return-to-zero signal is demonstrated.

    DOI

  • Product-sum photonic integrated circuit based on microring resonators and MMI coupler on SOI

    Ruikang Luo, Kiyoto Takahata

    Proceedings of the International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD   2021-September   127 - 128  2021.09  [Refereed]

     View Summary

    A product-sum photonic integrated circuit consisting of SOI-based cascaded microring modulators and a 4×1 multimode interference coupler is proposed for CNN computing. A basic product-sum operation is numerically demonstrated for 2×2 matrix.

    DOI

  • 50-GHz-bandwidth Membrane InGaAsP Electro-absorption Modulator on Si Platform

    Tatsurou Hiraki, Takuma Aihara, Yoshiho Maeda, Takuro Fujii, Tai Tsuchizawa, Kiyoto Takahata, Takaaki Kakitsuka, Shinji Matsuo

    Journal of Lightwave Technology   39 ( 16 ) 5300 - 5306  2021.05  [Refereed]

    DOI

  • "Vertical optical waveguide comprising square base cuboid cores with size modulation for multilayer chip-to-chip interconnection "

    Songping Ran, Takaaki Kakitsuka, Kiyoto Takahata

    Proc. of the 8th International Conference on Photonics, Optics and Laser Technology (PTOTOPTICS 2020) ,     174 - 179  2020  [Refereed]

  • "50-GHz-bandwidth Electro-absorption Modulator with Membrane InGaAsP Lateral p-i-n Diode on Si Platform"

    T. Hiraki, T. Aihara, Y. Maeda, T. Fujii, T. Tsuchizawa, K. Takahata, T. Kakitsuka, S. Matsuo

    European Conference on Optical Communication (ECOC2020), Tu1B-4    2020  [Refereed]

  • "Edge Model Embedding Method for Planar Filter Synthesis "

    Kosuke Katayama, Kiyoto Takahata, Takashi Ohsawa, Takaaki Baba

    RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP)     502 - 505  2019  [Refereed]

  • "New evaluation method of crosstalk penalty for PAM4 signals "

    Siyuan Duan, Hanzhi Chen, Qiang Du, Kiyoto Takahata

    Asia Communications and Photonics Conference (ACP2019), M4A.269    2019  [Refereed]

  • "A waveguide-based bidirectional optical delay unit with Bragg reflectors "

    Chenge Ao, Ruikang Luo, Kiyoto Takahata

    Asia Communications and Photonics Conference (ACP2019), M4A.288    2019  [Refereed]

  • 30-km Error-Free Transmission of Directly Modulated DFB Laser Array Transmitter Optical Sub-Assembly for 100-Gb Application

    Shigeru Kanazawa, Wataru Kobayashi, Yuta Ueda, Takeshi Fujisawa, Kiyoto Takahata, Tetsuichiro Ohno, Toshihide Yoshimatsu, Hiroyuki Ishii, Hiroaki Sanjoh

    JOURNAL OF LIGHTWAVE TECHNOLOGY   34 ( 15 ) 3646 - 3652  2016.08  [Refereed]

     View Summary

    We fabricated the first compact 100-gigabit Ethernet (100GbE) transmitter optical sub-assembly (TOSA) using a directly modulated DFB laser (DML) array monolithically integrated with an optical multiplexer. Specially designed InGaAlAs/InGaAlAs multiple quantum wells make it possible to obtain a large gain in the 1295-1310-nm wavelength range and to operate at a high temperature of 55 degrees C. The four-channel DML array chip is only 2.0 mm x 2.4 mm in size, and the fabricated TOSA is only 7.2 mm(W) x 14.3 mm(L) x 6.5 mm(H), which fits a CFP2 or smaller 100-GbE transceiver. For all the lanes, the 3-dB bandwidths of the TOSA exceeded 17 GHz, and it could operate at 25.8 Gb/s. With 25.8-Gb/s x four-channel simultaneous operation, error-free transmissions over a 30-km single-mode fiber were demonstrated for all the lanes.

    DOI

  • Compact Hybrid-Integrated 100-Gb/s TOSA Using EADFB Laser Array and AWG Multiplexer

    Takaharu Ohyama, Yoshiyuki Doi, Wataru Kobayashi, Shigeru Kanazawa, Takuya Tanaka, Kiyoto Takahata, Atsushi Kanda, Takeshi Kurosaki, Tetsuichiro Ohno, Hiroaki Sanjoh, Toshikazu Hashimoto

    IEEE PHOTONICS TECHNOLOGY LETTERS   28 ( 7 ) 802 - 805  2016.04  [Refereed]

     View Summary

    We have developed a compact hybrid-integrated four-lane x25.8 Gb/s transmitter optical sub-assembly (TOSA) for a 100 Gb/s transceiver for 40-km transmission. The TOSA has a simple configuration in which a four-channel electroabsorption modulator integrated distributed feedback (EADFB) laser array is directly attached to the input waveguide end-faces of a silica-based arrayed waveguide grating (AWG) multiplexer. We integrated a lateral tapered spot-size converter for the EADFB laser to achieve a high optical butt coupling efficiency between the EADFB lasers array and the AWG multiplexer. We confirmed that the TOSA, which is 19.9 mm x 6 mm x 5.8 mm, achieved error-free operation for a 40-km transmission with a high average optical output power of over 0.3 dBm at an operating temperature of 55 degrees C.

    DOI

  • Compact Hybrid Integrated 100-Gb/s Transmitter Optical Sub-Assembly Using Optical Butt-Coupling Between EADFB Lasers and Silica-Based AWG Multiplexer

    Takaharu Ohyama, Yoshiyuki Doi, Wataru Kobayashi, Shigeru Kanazawa, Kiyoto Takahata, Atsushi Kanda, Takeshi Kurosaki, Takuya Tanaka, Tetsuichiro Ohno, Hiroaki Sanjoh, Toshikazu Hashimoto

    JOURNAL OF LIGHTWAVE TECHNOLOGY   34 ( 3 ) 1038 - 1046  2016.02  [Refereed]

     View Summary

    A compact hybrid-integrated 100 Gb/s (4 lane x 25.78125 Gb/s) transmitter optical sub-assembly (TOSA) has been developed for a 100 Gb/s transceiver for 40-km transmission over a single-mode fiber. The TOSA has a simple configuration in which four electro-absorptionmodulator-integrated distributed feedback (EADFB) lasers are directly attached to the input waveguide end-face of a silica-based arrayed waveguide grating (AWG) multiplexer without bulk lenses. To achieve a high optical butt coupling efficiency between the EADFB lasers and the AWG multiplexer, we integrated a laterally tapered spot-size converter (SSC) for the EADFB laser and employed a waveguide with a high refractive index difference of 2.0% for the AWG multiplexer. By optimizing the laterally tapered SSC structure, we achieved a butt-coupling loss of less than 3 dB, which is an improvement of around 2 dB compared with a laser without an SSC structure. We also developed an ultracompact AWG multiplexer, which was 6.7 mm x 3.5 mm in size with an insertion loss of less than 1.9 dB. We achieved this by using aMach-Zehnder interferometer-synchronized configuration to obtain a low loss and wide flat-top transmission filter spectra. The TOSA body size was 19.9 mm (L) x 6.0 mm (W) x 5.8 mm (H). Error-free operation was demonstrated for a 40-km transmission when all the lanes were driven simultaneously with a low EA modulator driving voltage of 1.5 V at an operating temperature of 55 degrees C.

    DOI

  • Flip-Chip Interconnection Technique for Beyond 100-Gb/s (4 x 25.8-Gb/s) EADFB Laser Array Transmitter

    Shigeru Kanazawa, Takeshi Fujisawa, Kiyoto Takahata, Yuta Ueda, Hiroyuki Ishii, Ryuzo Iga, Wataru Kobayashi, Hiroaki Sanjoh

    JOURNAL OF LIGHTWAVE TECHNOLOGY   34 ( 2 ) 296 - 302  2016.01  [Refereed]  [Invited]

     View Summary

    We developed a flip-chip interconnection technique that is suitable for an EADFB laser array transmitter operating at more than 100 Gb/s (4 x 25 Gb/s). The flip-chip interconnection technique provides a good thermal flow comparable to that of the conventional wire interconnection technique but with a higher modulation bandwidth and lower electrical crosstalk. For a flip-chip interconnection 112-Gb/s (4 x 27.9 Gb/s) module, the OTU4 mask margin is only 4% worse for simultaneous four-channel operation than for single-channel operation. For a flip-chip interconnection 400-Gb/s (8 x 50 Gb/s) module, we obtained clear eye openings for all eight lanes with simultaneous eight-channel operation.

    DOI

  • 56-Gbaud 4-PAM (112-Gbit/s) operation of flip-chip interconnection lumped-electrode EADFB laser module for equalizer-free transmission

    Shigeru Kanazawa, Takeshi Fujisawa, Kiyoto Takahata, Yasuhiko Nakanishi, Hiroshi Yamazaki, Yuta Ueda, Wataru Kobayashi, Yoshifumi Muramoto, Hiroyuki Ishii, Hiroaki Sanjoh

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

     View Summary

    We fabricated a lumped-electrode type EADFB laser module using a flip-chip interconnection technique which provides a large modulation bandwidth. We obtained clear 56-Gbaud 4-PAM signal after 10-km SMF transmission with no equalizer using this module.

  • Transmission of 214-Gbit/s 4-PAM signal using an ultra-broadband lumped-electrode EADFB laser module

    Shigeru Kanazawa, Hiroshi Yamazaki, Yasuhiko Nakanishi, Takeshi Fujisawa, Kiyoto Takahata, Yuta Ueda, Wataru Kobayashi, Yoshifumi Muramoto, Hiroyuki Ishii, Hiroaki Sanjoh

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

     View Summary

    Using a lumped-electrode EADFB laser with a modulation bandwidth of similar to 59 GHz, we demonstrated single-wavelength single-polarization direct-detection 4-PAM transmission with the record net data rate of 200 Gbit/s.

  • Low Driving Voltage Operation of MZI-Type EA Modulator Integrated With DFB Laser Using Optical Absorption and Interferometric Extinction

    Yuta Ueda, Takeshi Fujisawa, Shigeru Kanazawa, Wataru Kobayashi, Kiyoto Takahata, Hiroaki Sanjoh, Hiroyuki Ishii, Masaki Kohtoku

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS   21 ( 6 ) 1501306  2015.11  [Refereed]

     View Summary

    We have developed a novel electroabsorption modulator (EAM)-integrated distributed feedback laser (EA-DFB laser), in which an EAM functioning as an external modulator is integrated in a Mach-Zehnder interferometer (MZI). The MZI-type EAM (MZEA) modulates light intensity by both optical absorption and interferometric extinction. As a result, it improves the extinction ratio (ER) of a conventional EAM, which allows us to reduce the modulation voltage (V-m), and thus reduce the power consumption of the driver circuit. A fabricated MZEA-integrated DFB laser (MZEA-DFB laser) exhibited high-ER operation and an output power of about 8 dBm, which is comparable to that of a conventional EA-DFB laser, with a 100-mA laser current. Thanks to the high ER and sufficient output power, the MZEA-DFB laser operating at half the V-m of a conventional EA-DFB laser is able to generate optical signals with a given optical modulation amplitude, and we achieved a 25.8-Gb/s 40-km transmission with the novel laser at a V-m of 1V(pp).

    DOI

  • High-Speed (400 Gb/s) Eight-Channel EADFB Laser Array Module Using Flip-Chip Interconnection Technique

    Shigeru Kanazawa, Takeshi Fujisawa, Hiroyuki Ishii, Kiyoto Takahata, Yuta Ueda, Ryuzo Iga, Hiroaki Sanjoh

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS   21 ( 6 ) 1501106  2015.11  [Refereed]

     View Summary

    We fabricated a 400-G flip-chip interconnection eight-channel EADFB laser array module. The flip-chip interconnection technique provides a higher modulation bandwidth and lower electrical crosstalk than the wire interconnection technique. The 3-dB bandwidth of the flip-chip interconnection subassembly was about 50 GHz. And the electrical crosstalk of the flip-chip interconnection module was suppressed to less than -20 dB below 35 GHz. We obtained clear eye openings for all eight lanes under eight-channel 50-Gb/s simultaneous operation after a 10-km SMF transmission.

    DOI

  • Flip-Chip Interconnection Lumped-Electrode EADFB Laser for 100-Gb/s/lambda Transmitter

    Shigeru Kanazawa, Takeshi Fujisawa, Kiyoto Takahata, Toshio Ito, Yuta Ueda, Wataru Kobayashi, Hiroyuki Ishii, Hiroaki Sanjoh

    IEEE PHOTONICS TECHNOLOGY LETTERS   27 ( 16 ) 1699 - 1701  2015.08  [Refereed]

     View Summary

    We have achieved the 100-Gb/s/lambda operation of a flip-chip interconnection 1.3-mu m lumped-electrode electroabsorption modulator integrated with a distributed feedback laser module for the first time. The flip-chip interconnection provides a flatter frequency response characteristic and a higher modulation bandwidth. Clear eye opening was achieved for 103-Gb/s nonreturn to zero and equalizer-free 56-GBd 4-pulse-amplitude modulation operation after a 10-km single-mode fiber transmission.

    DOI

  • Transmitter Optical Subassembly Using a Polarization Beam Combiner for 100 Gbit/s Ethernet over 40-km Transmission

    Takaharu Ohyama, Akira Ohki, Kiyoto Takahata, Toshio Ito, Nobuhiro Nunoya, Hiroyasu Mawatari, Takeshi Fujisawa, Shigeru Kanazawa, Ryuzo Iga, Hiroaki Sanjoh

    JOURNAL OF LIGHTWAVE TECHNOLOGY   33 ( 10 ) 1985 - 1992  2015.05  [Refereed]

     View Summary

    A transmitter optical subassembly (TOSA) has been developed for a 100-Gbit/s Ethernet system for a long optical transmission distance over a 40-km single-mode fiber (SMF). To obtain a high optical output power and a high dynamic extinction ratio, the TOSA consists of two two-channel distributed feedback laser diode array chips integrated with electro-absorption modulators (EADFB laser array chips) with a 2 x 1 multimode interference (MMI) optical coupler and a polarization beam combiner for wavelength multiplexing. The TOSA is 8.7 mm x 28.7 mm x 6.5 mm including an LC-type receptacle. The TOSA has a twin collimator path for two EADFB laser array chips. The wavelength multiplexer consists of a mirror, a half-wavelength plate, and a polarization beam combiner. The TOSA could improve the optical output power by around 2 dB compared with a TOSA with a four-channel EADFB laser array chip and a 4 x 1 MMI optical coupler. An optical modulation amplitude of over 0.5 dBm and a mask margin exceeding 21% were obtained for each lane when all lanes were operated simultaneously with an EA modulator driving voltage of 1.5 V at a bit rate of 25.78125 Gbit/s, which fully satisfies the 100GBASE-ER4 specifications. We demonstrated error-free operation for an SMF transmission of over 40 km. Moreover, we confirmed that the TOSA was capable of error-free SMF transmission over 60 km with a power penalty of less than 1.4 dB.

    DOI

  • Flip-chip mounted 25.8-Gb/s directly modulated InGaAsP DFB laser with Ru-doped semi-insulating buried heterostructure

    Shigeru Kanazawa, Toshio Ito, Tomonari Sato, Ryuzo Iga, Wataru Kobayashi, Kiyoto Takahata, Hiroaki Sanjoh, Hiroyuki Ishii

    IEICE ELECTRONICS EXPRESS   12 ( 1 ) 1 - 4  2015  [Refereed]

     View Summary

    The first directly modulated InGaAsP DFB laser module using the flip-chip mounting technique was fabricated for 25.8-Gb/s operation. The fabricated laser chip has p-and n-electrodes on the surface side. This structure is suitable for flip-chip mounting, which provides a high modulation bandwidth. The fabricated module provided clear eye opening with a dynamic extinction ratio of over 4 dB when operated 25.8 Gb/s.

    DOI

  • 400-Gb/s Operation of Flip-chip Interconnection EADFB Laser Array Module

    Shigeru Kanazawa, Takeshi Fujisawa, Kiyoto Takahata, Hiroaki Sanjoh, Ryuzo Iga, Yuta Ueda, Wataru Kobayashi, Hiroyuki Ishii

    2015 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)    2015  [Refereed]  [Invited]

     View Summary

    The flip-chip interconnection 8-channel EADFB laser array module is developed. The flip-chip interconnection technique provides low crosstalk. After 10-km transmission, clear eye opening is obtained for all eight lanes under 8 x 50-Gb/s simultaneous operation.

  • High-linearity Avalanche Photodiode for 40-km Transmission with 28-Gbaud PAM4

    Masahiro Nada, Shigeru Kanazawa, Hiroshi Yamazaki, Yasuhiko Nakanishi, Wataru Kobayashi, Yoshiyuki Doi, Takaharu Ohyama, Tetsuichiro Ohno, Kiyoto Takahata, Toshikazu Hashimoto, Hideaki Matsuzaki

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

     View Summary

    We present a high-linearity avalanche photodiode (APD) for 28-Gbaud PAM4, namely, 56 Gbit/s/X. With an optical receiver incorporating the APD, a 40-km transmission with-17 dBm receiver sensitivity was successfully demonstrated for the first time.

  • Compact Hybrid-integrated 100-Gbit/s TOSA for 40-km Transmission

    Takaharu Ohyama, Yoshiyuki Doi, Shigeru Kanazawa, Kiyoto Takahata, Atsushi Kanda, Takeshi Kurosaki, Tetsuichiro Ohno, Hiroaki Sanjoh, Wataru Kobayashi, Takuya Tanaka, Toshikazu Hashimoto

    2015 OPTO-ELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC)    2015  [Refereed]

     View Summary

    We developed a compact hybrid-integrated 100 Gbit/s TOSA using an EADFB laser array with a spot-size converter and a silica-based AWG multiplexer. Error-free operation for a 40-km transmission was demonstrated at an operating temperature of 55 degrees C.

  • Very-low-voltage operation of Mach-Zehnder interferometer-type electroabsorption modulator using asymmetric couplers

    Y. Ueda, T. Fujisawa, S. Kanazawa, W. Kobayashi, K. Takahata, H. Ishii

    OPTICS EXPRESS   22 ( 12 ) 14610 - 14616  2014.06  [Refereed]

     View Summary

    We have proposed and developed a new type of electroabsorption modulator (EAM) that employs both optical absorption and interferometric extinction. The EAM operates at a record low voltage of 0.2 V at 25.8-Gbit/s modulation, which can reduce optical transmitter power consumption and allows the adoption of cost-effective CMOS drivers. (C) 2014 Optical Society of America

    DOI

  • InP-based compact transversal filter for monolithically integrated light source array

    Yuta Ueda, Takeshi Fujisawa, Kiyoto Takahata, Masaki Kohtoku, Hiroyuki Ishii

    OPTICS EXPRESS   22 ( 7 ) 7844 - 7851  2014.04  [Refereed]

     View Summary

    We developed an InP-based 4x1 transversal filter (TF) with multi-mode interference couplers (MMIs) as a compact wavelength multiplexer (MUX) 1700 mu m x 400 mu m in size. Furthermore, we converted the MMI-based TF to a reflection type to obtain an ultra-compact MUX of only 900 mu m x 50 mu m. These MUXs are made with a simple fabrication process and show a satisfactory wavelength filtering operation as MUXs of monolithically integrated light source arrays, for example, for 100G bit Ethernet. (C) 2014 Optical Society of America

    DOI

  • Compact flip-chip interconnection 8 x 50 Gbit/s EADFB laser array module for 400 Gbit/s transceiver

    S. Kanazawa, T. Fujisawa, A. Ohki, K. Takahata, H. Sanjoh, R. Iga, H. Ishii

    ELECTRONICS LETTERS   50 ( 7 ) 533 - +  2014.03  [Refereed]

     View Summary

    The first compact electroabsorption modulators integrated with distributed-feedback (EADFB) laser array module using flip-chip interconnects have been fabricated for a 400 Gbit/s transceiver. Eight 50 Gbit/s EADFB lasers and an optical multiplexer were monolithically integrated on one chip in an area of only 3.2 x 4.8 mm. The flip-chip interconnects provide a higher modulation bandwidth. Clear eye opening was achieved for all eight lanes under 50 Gbit/s operation.

    DOI

  • Compact Flip-Chip Interconnection 112-Gbit/s EADFB Laser Array Module With High Eye-Mask Margin

    Shigeru Kanazawa, Takeshi Fujisawa, Nobuhiro Nunoya, Akira Ohki, Kiyoto Takahata, Hiroaki Sanjoh, Ryuzo Iga, Hiroyuki Ishii

    JOURNAL OF LIGHTWAVE TECHNOLOGY   32 ( 1 ) 115 - 121  2014.01  [Refereed]

     View Summary

    The first compact and high-performance optical transmitter using flip-chip interconnects has been developed for a 112-Gbit/s transceiver. The flip-chip interconnects provide lower crosstalk and a higher modulation bandwidth than wire interconnects. The flip-chip interconnection module has 3-dB frequency bandwidths of over 30 GHz. This value is up to 5 GHz better than that of a wire interconnection module. Under four-channel simultaneous operation, the OTU4 mask margins for all four lanes of the flip-chip interconnection module exceed 37%. These values are degraded up to only 4% compared with those for single-channel operation. In addition, an error-free transmission through 10 km of single-mode fiber at 112 Gbit/s is demonstrated.

    DOI

  • Successful demonstration of low-voltage (1 V-pp) MZI-type EAM-integrated DFB laser for 25.8-Gbit/s 40-km transmission

    Y. Ueda, T. Fujisawa, S. Kanazawa, W. Kobayashi, K. Takahata, H. Sanjoh, H. Ishii

    2014 24TH IEEE INTERNATIONAL SEMICONDUCTOR LASER CONFERENCE (ISLC 2014)     52 - 53  2014  [Refereed]

     View Summary

    We developed a new type of EAM-integrated DFB laser that employs both optical absorption and interferometric extinction. And, we achieve a 25.8-Gbit/s 40-km transmission with the novel laser at a modulation voltage of 1 V-pp.

    DOI

  • 8 x 50-Gb/s simultaneous operation of EADFB laser array using flip-chip

    S. Kanazawa, T. Fujisawa, K. Takahata, H. Sanjoh, R. Iga, H. Ishii

    2014 24TH IEEE INTERNATIONAL SEMICONDUCTOR LASER CONFERENCE (ISLC 2014)     58 - 59  2014  [Refereed]

     View Summary

    We fabricated an eight-channel EADFB laser array sub-assembly using a flip-chip interconnection technique that provided a low crosstalk. We achieved clear eye openings for all eight lanes with 8 x 50-Gb/s simultaneous operation.

    DOI

  • Compact 100 Gb/s Ethernet Transmitter Optical Sub-Assembly Using Polarization Beam Combiner

    Takaharu Ohyama, Akira Ohki, Kiyoto Takahata, Toshio Ito, Nobuhiro Nunoya, Takeshi Fujisawa, Shigeru Kanazawa, Ryuzo Iga, Hiroaki Sanjoh

    IEEE PHOTONICS TECHNOLOGY LETTERS   25 ( 24 ) 2416 - 2418  2013.12  [Refereed]

     View Summary

    A compact transmitter optical sub-assembly (TOSA) has been developed for a 100 Gb/s Ethernet system with a long transmission distance of 40 km over single-mode fiber. The TOSA consists of electro-absorption modulator integrated distributed feedback laser diode arrays and a polarization beam combiner for wavelength multiplexing to obtain a high optical output power and a high dynamic extinction ratio. We confirmed that the TOSA successfully achieved an error-free four-lane x 25.8 Gb/s transmission, i.e., a total bit-rate of 100 Gb/s, over 40 km.

    DOI

  • Compact 100 Gb/s Ethernet Transmitter Optical Sub-Assembly Using Polarization Beam Combiner

    Takaharu Ohyama, Akira Ohki, Kiyoto Takahata, Toshio Ito, Nobuhiro Nunoya, Takeshi Fujisawa, Shigeru Kanazawa, Ryuzo Iga, Hiroaki Sanjoh

    IEEE PHOTONICS TECHNOLOGY LETTERS   25 ( 24 ) 2416 - 2418  2013.12  [Refereed]

     View Summary

    A compact transmitter optical sub-assembly (TOSA) has been developed for a 100 Gb/s Ethernet system with a long transmission distance of 40 km over single-mode fiber. The TOSA consists of electro-absorption modulator integrated distributed feedback laser diode arrays and a polarization beam combiner for wavelength multiplexing to obtain a high optical output power and a high dynamic extinction ratio. We confirmed that the TOSA successfully achieved an error-free four-lane x 25.8 Gb/s transmission, i.e., a total bit-rate of 100 Gb/s, over 40 km.

    DOI

  • Low-Loss Cascaded Mach-Zehnder Multiplexer Integrated 25-Gbit/s x 4-Lane EADFB Laser Array for Future CFP4 100 GbE Transmitter

    Takeshi Fujisawa, Shigeru Kanazawa, Yuta Ueda, Wataru Kobayashi, Kiyoto Takahata, Akira Ohki, Toshio Ito, Masaki Kohtoku, Hiroyuki Ishii

    IEEE JOURNAL OF QUANTUM ELECTRONICS   49 ( 12 ) 1001 - 1007  2013.12  [Refereed]

     View Summary

    A 4 x 25-Gb/s electroabsorption modulator integrated with a distributed feedback (DFB) laser (EADFB laser) array monolithically integrated with a low-loss optical multiplexer (MUX) is developed for 100 GbE transmitters for the first time. A cascaded Mach-Zehnder (MZ) filter, which has no intrinsic loss, is used as the MUX. The design and fabrication of the MZ-MUX for 100 GbE are thoroughly described. The measured loss of fabricated MZ-MUX is 2-3 dB, which is improved by 4 dB compared with that of the conventional 1 x 4 multimode interference MUX. The MZ-MUX is monolithically integrated with a four-EADFB-laser array and the output power of the chip is increased by 3 dB compared with that of a conventional 4 x 25-Gb/s monolithically integrated chip. With the folded layout, the size of the chip is similar to that of the conventional chip. The fabricated chip is packaged into a very compact transmitter optical subassembly (TOSA). The system requirements are satisfied with semi-cooled operation, and very clear eye openings are obtained after 10-km single-mode-fiber transmission. The adjustment of filter spectra by current injection is also shown, and fine tuning is possible with very low injection current.

    DOI

  • Ultracompact, 160-Gbit/s transmitter optical subassembly based on 40-Gbit/s x 4 monolithically integrated light source

    Takeshi Fujisawa, Toshio Itoh, Shigeru Kanazawa, Kiyoto Takahata, Yuta Ueda, Ryuzo Iga, Hiroaki Sanjo, Takayuki Yamanaka, Masaki Kotoku, Hiroyuki Ishii

    OPTICS EXPRESS   21 ( 1 ) 182 - 189  2013.01

     View Summary

    The first ultracompact transmitter optical subassembly for long-distance, beyond-100-Gbit/s data communication systems based on a monolithically integrated light source is developed. The light source consists of four InGaAlAs-based electroabsorption modulator integrated DFB lasers (EADFB lasers) and their optical multiplexer and these components are monolithically integrated on one chip, resulting in very small chip size of 2.4 x 3.3 mm(2). This small chip makes it possible to reduce the size of the transmitter module. Very small transmitter optical subassemblies (TOSAs), using the chip and employing three-dimensional interconnection board, is fabricated, whose volume is only 1.82 cc. By using the TOSA, 40-Gbit/s x 4 operation with the clear eye openings up to 10-km single mode fibre transmission is demonstrated. Electrical crosstalk under the multi-lane operation is also evaluated, and the error-free transmission is achieved with the power penalty to the discrete operation of 1 dB. (C) 2013 Optical Society of America

    DOI

  • 50 Gbit/s uncooled operation (5-85 degrees C) of 1.3 mu m electroabsorption modulator integrated with DFB laser

    T. Fujisawa, S. Kanazawa, W. Kobayashi, K. Takahata, A. Ohki, R. Iga, H. Ishii

    ELECTRONICS LETTERS   49 ( 3 ) 204 - 205  2013.01  [Refereed]

     View Summary

    The first uncooled operation (5-85 degrees C) at 50 Gbit/s of a 1.3 mu m electroabsorption modulator integrated with a DFB laser is achieved and 10 km transmission on singlemode fibre with very clear eye openings is demonstrated.

    DOI

  • Ultra-compact 100 GbE transmitter optical sub-assembly for 40-km SMF transmission

    Shigeru Kanazawa, Takeshi Fujisawa, Nobuhiro Nunoya, Akira Ohki, Kiyoto Takahata, Hiroaki Sanjoh, Ryuzo Iga, Hiroyuki Ishii

    Journal of Lightwave Technology   31 ( 4 ) 602 - 608  2013  [Refereed]

     View Summary

    The first ultra-compact transmitter optical sub-assembly (TOSA) has been developed for the metro-area 100 Gbit/s Ethernet (100 GbE) system. Four DFB lasers integrated with electro-absorption modulators (EADFB lasers) operated at 25.8 Gbit/s and an optical multiplexer are monolithically integrated on one chip. The chip was assembled in the compact TOSA using a three-dimensional (3D) RF circuit board supported by a spacer. The new structure provides compact and high-density interconnection with low crosstalk between RF signal lines. The TOSA is very small at just 8.0 mm × 35 mm × 6.5 mm including the receptacle and the flexible printed circuit (FPC) and could be installed in next-generation small form 100 GbE transceivers. In addition, an error-free transmission is demonstrated through 40 km of single-mode fiber at 100 Gbit/s with a modulation voltage of 2 V. © 1983-2012 IEEE.

    DOI

  • InP-based Compact Reflection-Type Transversal Filter

    Y. Ueda, T. Fujisawa, K. Takahata, M. Kohtoku, H. Takahashi, H. Ishii

    2013 INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE AND RELATED MATERIALS (IPRM)    2013  [Refereed]

     View Summary

    We developed a reflection-type 4x1 transversal filter (TF) on an InP substrate as a compact and low-loss wavelength multiplexer (MUX) for monolithically integrated light source arrays. The filter has a satisfactory MUX function and is very compact of about 900 mu m x 50 mu m which is one twentieth of a size of a conventional 4x1 TF. It is suitable for a MUX of a monolithically integrated light source array thanks to its compactness and input/output-port arrangement.

  • Low crosstalk and high modulation bandwidth 100GbE optical transmitter using flip-chip interconnects

    Shigeru Kanazawa, Takeshi Fujisawa, Kiyoto Takahata, Akira Ohki, Ryuzo Iga, Hiroyuki Ishii

    Conference Proceedings - International Conference on Indium Phosphide and Related Materials    2013  [Refereed]

     View Summary

    We developed the first compact 100GbE optical transmitter to use flip-chip interconnects for the first time. The flip-chip interconnects provide low crosstalk and a high modulation bandwidth. Under four-channel simultaneous operation, the 100GBASE-LR4 mask margin of the flip-chip interconnection module was improved by 10% to 27% compared with that of a wire interconnection module. © 2013 IEEE.

    DOI

  • “4× 25-Gbit/s EADFB laser array monolithically integrated with cascaded Mach-Zhender multiplexer”

    T. Fujisawa, S. Kanazawa, Y. Ueda, W. Kobayashi, K. Takahata, A. Ohoki, T. Itoh, M. Kotoku, H. Ishii

    Opt-Electronics and Communications Conference (OECC2013), MK1-3    2013  [Refereed]

  • Very-low-voltage operation of mach-zehnder interferometer-type electroabsorption modulator

    Y. Ueda, T. Fujisawa, S. Kanazawa, W. Kobayashi, K. Takahata, H. Ishii

    IET Conference Publications   2013 ( 622 ) 342 - 344  2013  [Refereed]

     View Summary

    We have proposed and developed a new type of electroabsorption modulator (EAM) that employs both optical absorption and interferometric extinction. The EAM operates at a record-low voltage of 0.2 V at 25.8-Gbit/s modulation, which can reduce optical transmitter power consumption and allows the adoption of cost-effective CMOS drivers.

    DOI

  • 1.3-mu m, 4 x 25-Gbit/s, EADFB laser array module with large-output-power and low-driving-voltage for energy-efficient 100GbE transmitter

    Takeshi Fujisawa, Shigeru Kanazawa, Kiyoto Takahata, Wataru Kobayashi, Takashi Tadokoro, Hiroyuki Ishii, Fumiyoshi Kano

    OPTICS EXPRESS   20 ( 1 ) 614 - 620  2012.01  [Refereed]

     View Summary

    A 1.3-mu m, 4 x 25-Gbit/s, EADFB laser array module with large output power and low driving voltage is developed for 100GbE. A novel rear grating DFB laser is introduced to increase the output power of the laser while keeping the single mode lasing, which is desirable for a monolithic integration. Also, InGaA1As-based electroabsorption modulators make very-low-driving-voltage operation possible due to their steep extinction curves. With the module, very clear 25-Gbit/s eye openings are obtained for four wavelengths with the driving voltage of only 0.5 V while securing the dynamic extinction ratio required by the system. These results indicate that the presented module is a promising candidate for energy-efficient future 100GbE transmitter. (C) 2011 Optical Society of America

  • “Extremely small-form 100GbE transmitter optical sub-assembly for future inter data center cloud networks”

    S. Kanazawa, T. Fujisawa, N. Nunoya, A. Ohki, K. Takahata, H. Sanjoh, R. Iga, H. Ishii

    Optical Fiber Communications Conference (OFC2012), PDP-5B.8    2012  [Refereed]

  • Theoretical and Experimental Investigations of Laser Characteristics of Novel Rear-Grating Structure and Its Application to Uncooled Light Source

    T. Fujisawa, K. Takahata, W. Kobayashi, R. Iga, H. Ishii

    2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)    2012  [Refereed]

     View Summary

    The mechanisms of increased output power and stable single-mode lasing characteristics of novel rear-grating laser are both theoretically and experimentally investigated and its application to uncooled light source is demonstrated for the first time. (C)2012 Optical Society of America

  • Ultra-high-speed electroabsorption modulator integrated lasers for 100GbE and beyond

    T. Fujisawa, S. Kanazawa, K. Takahata, W. Kobayashi, T. Tadokoro, R. Iga, H. Ishii

    Technical Digest - 2012 17th Opto-Electronics and Communications Conference, OECC 2012     75 - 76  2012  [Invited]

     View Summary

    Recent progress in electroabsorption modulator integrated lasers for high-speed data communications is reviewed. The design of discrete components for high-speed operation and low-power-consumption as well as their large-scale-integration technologies are described. © 2012 IEEE.

    DOI

  • Ultracompact, 160-Gbit/s Transmitter Optical Subassembly Based on 40-Gbit/s x 4 Monolithically Integrated Light Source

    Takeshi Fujisawa, Shigeru Kanazawa, Kiyoto Takahata, Akira Ohki, Yuta Ueda, Ryuzo Iga, Hiroaki Sanjo, Takayuki Yamanaka, Masaki Kohtoku, Hiroyuki Ishii

    2012 38TH EUROPEAN CONFERENCE AND EXHIBITION ON OPTICAL COMMUNICATIONS (ECOC)    2012  [Refereed]

     View Summary

    The first ultracompact transmitter optical subassembly for long-distance, beyond-100-Gbit/s data communication systems based on a monolithically integrated light source is developed, and 40Gbit/sx 4 operation with the clear eye openings up to 10-km single mode fibre transmission is demonstrated.

  • Extremely Compact Transmitter Optical Sub-assembly for Next-generation 10-km 100GbE Transceivers

    K. Takahata, T. Fujisawa, A. Ohki, S. Kanazawa, T. Yamanaka, H. Sanjoh, R. Iga, H. Ishii

    2012 23RD IEEE INTERNATIONAL SEMICONDUCTOR LASER CONFERENCE (ISLC)     56 - 57  2012  [Refereed]

     View Summary

    An extremely compact 1.3-mu m, 4x25-Gbit/s TOSA was made by using monolithically integrated EADFB laser array with rear-grating DFB lasers. The dynamic extinction ratio and optical modulation amplitude are high enough for 10-km 100GbE.

  • "Electroabsorption Modulator Integrated Light Sources for Future High-speed Ethernet,"

    T. Fujisawa, S. Kanazawa, K. Takahata, H. Ishii

    NTT Technical Review   10 ( 12 ) 1 - 5  2012  [Invited]

  • Ultracompact, 160-Gbit/s Transmitter Optical Subassembly Based on 40-Gbit/s x 4 Monolithically Integrated Light Source

    Takeshi Fujisawa, Shigeru Kanazawa, Kiyoto Takahata, Akira Ohki, Yuta Ueda, Ryuzo Iga, Hiroaki Sanjo, Takayuki Yamanaka, Masaki Kohtoku, Hiroyuki Ishii

    2012 38TH EUROPEAN CONFERENCE AND EXHIBITION ON OPTICAL COMMUNICATIONS (ECOC)   21 ( 1 ) 182 - 189  2012  [Refereed]

     View Summary

    The first ultracompact transmitter optical subassembly for long-distance, beyond-100-Gbit/s data communication systems based on a monolithically integrated light source is developed, and 40Gbit/sx 4 operation with the clear eye openings up to 10-km single mode fibre transmission is demonstrated.

  • A Compact EADFB Laser Array Module for a Future 100-Gb/s Ethernet Transceiver

    Shigeru Kanazawa, Takeshi Fujisawa, Akira Ohki, Hiroyuki Ishii, Nobuhiro Nunoya, Yoshihiro Kawaguchi, Naoki Fujiwara, Kiyoto Takahata, Ryuzo Iga, Fumiyoshi Kano, Hiromi Oohashi

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS   17 ( 5 ) 1191 - 1197  2011.09  [Refereed]  [Invited]

     View Summary

    A compact electroabsorption modulators integrated distributed feedback (EADFB) laser array module has been developed for 100-Gb/s Ethernet. Four 25-Gb/s EADFB lasers and an optical multiplexer are monolithically integrated on one chip in an area of only 2 mm x 2.6 mm. As a result, a compact 12 mm x 20 mm EADFB laser array module is achieved. A bridge-type RF circuit board is employed to transmit high-frequency, 4 x 25-Gb/s, electrical signals effectively in a narrow package and improve the electrical/optical response of the module. The module has a 3-dB frequency bandwidth of 20 GHz for the four lanes assigned in 100-Gb/s Ethernet. Furthermore, the possibility of realizing low-driving voltage operation is investigated to reduce the power consumption of the module. An error-free transmission through 10 km of single-mode fiber at 100 Gb/s with a modulation voltage of only 1 V is demonstrated.

    DOI

  • Long-Reach 100 Gbit Ethernet Light Source Based on 4 x 25-Gbit/s 1.3-mu m InGaAlAs EADFB Lasers

    Takeshi Fujisawa, Kiyoto Takahata, Takashi Tadokoro, Wataru Kobayashi, Akira Ohki, Naoki Fujiwara, Shigeru Kanazawa, Takayuki Yamanaka, Fumiyoshi Kano

    IEICE TRANSACTIONS ON ELECTRONICS   E94C ( 7 ) 1167 - 1172  2011.07  [Refereed]

     View Summary

    High-performance 1.3-mu m electroabsorption modulators integrated with DFB lasers are developed for long-reach 100 Obit Ethernet. The dynamic extinction ratio of over 8-dB with the voltage swing of 2 V are achieved for the four LAN-WDM lanes (14 nm wavelength range) used in 100 Gbit Ethernet with the same modulator structure. The fabricated devices are packaged in butterfly modules and four-lane 40-km single mode fiber transmission at 25-Gbit/s operation is demonstrated. Further, a can-type transmitter optical subassembly is fabricated to reduce the cost and size of transmitter modules. The use of a low-dielectric-constant liquid crystal polymer transmission line makes the 3-dB bandwidth larger and enables 25-Gbit/s operation with CAN-TOSA module.

    DOI

  • 1.3 mu m, 50 Gbit/s electroabsorption modulators integrated with DFB laser for beyond 100G parallel LAN applications

    T. Fujisawa, K. Takahata, W. Kobayashi, T. Tadokoro, N. Fujiwara, S. Kanazawa, F. Kano

    ELECTRONICS LETTERS   47 ( 12 ) 708 - 710  2011.06  [Refereed]

     View Summary

    A 1.3 mu m, 50 Gbit/s electroabsorption modulator integrated with a DFB laser for future parallel LAN, the total data rate of which is over 100 Gbit/s, is developed. Very clear eye openings after 40 km transmission under 50 Gbit/s operation on singlemode fibre are demonstrated for eight wavelengths with discrete packages for the first time.

    DOI

  • 1.3-mu m 4 x 25-Gb/s Monolithically Integrated Light Source for Metro Area 100-Gb/s Ethernet

    T. Fujisawa, S. Kanazawa, H. Ishii, N. Nunoya, Y. Kawaguchi, A. Ohki, N. Fujiwara, K. Takahata, R. Iga, F. Kano, H. Oohashi

    IEEE PHOTONICS TECHNOLOGY LETTERS   23 ( 6 ) 356 - 358  2011.03  [Refereed]

     View Summary

    A 1.3-mu m monolithically integrated light source for metro area 100-Gb/s Ethernet is developed. Four 25-Gb/s electroabsorption modulators integrated with distributed-feedback lasers and their multiplexer are monolithically integrated on one chip. A shallow ridge waveguide is used for lasers and modulators for large modulation bandwidth, and a deep ridge waveguide is used for the multiplexer region due to its low bending and radiation losses. The integration of hetero-waveguide devices enables the very small chip size of 2 x 2.6 mm(2). With the device, 100-Gb/s (4 x 25-Gb/s simultaneous) operation is demonstrated with the clear eye-openings, and error-free 40-km single-mode fiber transmission is achieved for the first time.

    DOI

  • 1.3-mu m, 50-Gbit/s EADFB Lasers for 400GbE

    Takeshi Fujisawa, Kiyoto Takahata, Wataru Kobayashi, Takashi Tadokoro, Naoki Fujiwara, Shigeru Kanazawa, Fumiyoshi Kano

    2011 OPTICAL FIBER COMMUNICATION CONFERENCE AND EXPOSITION (OFC/NFOEC) AND THE NATIONAL FIBER OPTIC ENGINEERS CONFERENCE    2011  [Refereed]

     View Summary

    We have developed 1.3-mu m, 50-Gbit/s EADFB lasers for future 400Gbit Ethernet. 10-and 40-km SMF transmission with clear eye openings over 14-nm wavelength range under 50-Gbit/s operation are demonstrated for the first time.

  • “Monolithically integrated transmitter for 100GbE” (Invited)

    T. Fujisawa, S. Kanazawa, H. Ishii, N. Nunoyaa, Y. Kawaguchi, A. Ohki, N. Fujiwara, K. Takahata, R. Iga, F. Kano, H. Oohashi

    Opt-Electronics and Communications Conference (OECC2011)     458 - 459  2011  [Invited]

  • Large-Output-Power, Ultralow-Driving-Voltage (0.5 V-pp) Operation of 1.3-mu m, 4x25G, EADFB Laser Array for Driverless 100GbE Transmitter

    Takeshi Fujisawa, Sigeru Kanazawa, Kiyoto Takahata, Wataru Kobayashi, Takashi Tadokoro, Hiroyuki Ishii, Fumiyoshi Kano

    2011 37TH EUROPEAN CONFERENCE AND EXHIBITION ON OPTICAL COMMUNICATIONS (ECOC 2011)    2011  [Refereed]

     View Summary

    A large-output-power 1.3-mu m, 4x25G, EADFB laser array with a novel rear grating DFB laser is developed for 100GbE. Ultralow-driving-voltage operation (0.5 V-pp) is achieved for the first time with clear eye openings after 10-km transmission.

  • 1.3-mu m, 4x25G, EADFB Laser Array Module for Compact 10-km 100GbE Transceivers

    K. Takahata, T. Fujisawa, S. Kanazawa, F. Kano

    2011 IEEE PHOTONICS CONFERENCE (PHO)     208 - 209  2011  [Refereed]

     View Summary

    A 1.3-mu m, 4x25G, EADFB laser array with a novel rear grating DFB laser was developed and packaged in a compact module. It provides enough dynamic extinction ratio and averaged optical power for 10-km 100GbE.

  • 4 X 25-Gbit/s, 40-km SMF transmission based on 1.3-mu m electroabsorption modulators integrated with DFB lasers for 100-Gbit/s Ethernet

    T. Fujisawa, S. Kanazawa, K. Takahata, Y. Kawaguchi, A. Ohki, W. Kobayashi, N. Fujiwara, T. Tadokoro, T. Yamanaka, F. Kano

    2010 15TH OPTOELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC)     50 - 51  2010  [Refereed]

     View Summary

    High-performance 1.3-mu m InGaAlAs electroabsorption modulators integrated with DFB lasers are developed for long-reach 100-Gbit/s Ethernet system. Four-channel, 40-km SMF transmission at 25-Gbit/s operation is demonstrated for the first time.

  • 4x25-Gbit/s, 1.3-mu m, Monolithically Integrated Light Source for 100-Gbit/s Ethernet

    T. Fujisawa, S. Kanazawa, N. Nunoya, H. Ishii, Y. Kawaguchi, A. Ohki, N. Fujiwara, K. Takahata, R. Iga, F. Kano, H. Oohashi

    2010 36TH EUROPEAN CONFERENCE AND EXHIBITION ON OPTICAL COMMUNICATION (ECOC), VOLS 1 AND 2    2010  [Refereed]  [Invited]

     View Summary

    We have developed 4x25-Gbit/s, 1.3-mu m, monolithically integrated light source for 100-Gbit/s Ethernet (100GBASE-LR4) for the first time. Error-free transmission of 10-km on SMF under 100Gbit/s (4x25-Gbit/s simultaneous) operation is demonstrated.

  • Low-voltage operation of 100-Gbit/s EADFB laser array module

    S. Kanazawa, T. Fujisawa, A. Ohki, H. Ishii, N. Nunoya, Y. Kawaguchi, N. Fujiwara, K. Takahata, R. Iga, F. Kano, H. Oohashi

    22ND IEEE INTERNATIONAL SEMICONDUCTOR LASER CONFERENCE     57 - 58  2010  [Refereed]

     View Summary

    We developed a 4x25.8-Gbit/s EADFB laser array module for use as a 100-Gbit/s Ethernet transceiver. We demonstrated error-free transmission over a 10-km single-mode fiber at 100-Gbit/s with a modulation voltage of 1 V.

  • An optically clocked transistor array with dual serial-to-parallel and parallel-to-serial conversion capability for optical label swapping

    R Urata, R Takahashi, T Nakahara, K Takahata, H Suzuki

    IEEE PHOTONICS TECHNOLOGY LETTERS   18 ( 1-4 ) 67 - 69  2006.01  [Refereed]

     View Summary

    We propose an optically clocked transistor array optoelectronic integrated circuit (OEIC) for both serial-to-parallel and parallel-to-serial conversion (demux/mux), enabling an interface between high-speed asynchronous burst optical labels and CMOS circuitry for optical label swapping. Dual functionality of the OEIC reduces size, power, and cost of the optical label swapper. The capability for greater than 20-Gb/s conversion operation is demonstrated.

    DOI

  • High-speed optical packet processing technologies for optical packet-switched networks

    H Takenouchi, T Nakahara, K Takahata, R Takahashi, H Suzuki

    IEICE TRANSACTIONS ON ELECTRONICS   E88C ( 3 ) 286 - 294  2005.03  [Refereed]  [Invited]

     View Summary

    Asynchronous optical packet switching (OPS) is a promising solution to support the continuous growth of transmission capacity demand. It has been, however, quite difficult to implement key functions needed at the node of such networks with all-optical approaches. We have proposed a new optoelectronic system composed of a packet-by-packet optical clock-pulse generator (OCG), an all-optical serial-to-parallel converter (SPC), a photonic parallel-to-serial converter (PSC), and CMOS circuitry. The system makes it possible to carry out various required functions such as buffering (random access memory), optical packet compression/decompression, and optical label swapping for high-speed asynchronous optical packets.

    DOI

  • Optoelectronic packet switches for 40-Gb/s 16-bit asynchronous burst optical packets

    K Takahata, R Takahashi, T Nakahara, H Takenouchi, H Suzuki

    IEEE PHOTONICS TECHNOLOGY LETTERS   17 ( 3 ) 684 - 686  2005.03  [Refereed]

     View Summary

    We present two types of optoelectronic time-domain packet switches, a photonic add-drop multiplexer, and a 4 x 4 packet switch, for high-speed asynchronous burst optical packets. They employ all-optical serial-to-parallel converters, optical single clock-pulse generators, and photonic parallel-to-serial converters that enable utilization of a compact highly functional complementary metal-oxide-semiconductor circuitry for label processing, packet switching, and buffering for contention resolution. We have experimentally confirmed basic operation of the packet switches for 40-Gb/s 16-bit asynchronous optical packets.

    DOI

  • 3.3 ps electrical pulse generation from a discharge-based metal-semiconductor-metal photodetector

    K Takahata, R Takahashi, T Nakahara, H Takenouchi, H Suzuki

    ELECTRONICS LETTERS   41 ( 1 ) 38 - 40  2005.01  [Refereed]

     View Summary

    An ultrashort electrical pulse with a pulse width of 3.3 ps was generated successfully from an ordinary metal-semiconductor-metal photodetector simply by adding an input resistor and hold capacitor. The new detector not only provides ultrashort fall time, but also has other advantages such as ease of fabrication, high sensitivity, and low-bias operation.

    DOI

  • An optically clocked transistor array for dual serial-to-parallel and parallel-to-serial conversion of optical packets

    R Urata, R Takahashi, T Nakahara, K Takahata, H Suzuki

    2005 Conference on Lasers & Electro-Optics (CLEO), Vols 1-3   ( 1 ) 722 - 724  2005  [Refereed]

     View Summary

    We propose an optically clocked transistor array which performs both serial-to-parallel and parallel-to-serial conversion (time demux/mux) of incoming/outgoing packets, enabling a low cost, low power, compact optical label processor for asynchronous burst optical packets. (c) 2004 Optical Society of America

  • Time-domain 16-bit label swapping and self-routing of 40-Gb/s burst optical packets

    T Nakahara, R Takahashi, H Takenouchi, K Takahata, H Suzuki

    IEEE PHOTONICS TECHNOLOGY LETTERS   16 ( 9 ) 2153 - 2155  2004.09  [Refereed]

     View Summary

    A novel scheme for time-domain programmable label swapping for burst-mode asynchronous optical packets is described. Label recognition of input signals and generation of output signals with corresponding new labels are achieved by a complementary metal-oxide-semiconductor circuit sandwiched between input and output interfaces (all-optical serial-to-parallel and photonic parallel-to-serial converters, respectively) for fast serial-bit optical labels. Accurate synchronization in operating these interfaces is accomplished with an optical single-clock-pulse generator. Self-routing with 16-bit label swapping of 40-Gb/s optical packets is demonstrated.

    DOI

  • 40-Gb/s 32-bit optical packet compressor-decompressor based on an optoelectronic memory

    H Takenouchi, R Takahashi, K Takahata, T Nakahara, H Suzuki

    IEEE PHOTONICS TECHNOLOGY LETTERS   16 ( 7 ) 1751 - 1753  2004.07  [Refereed]

     View Summary

    We propose a novel optical packet compressor-decompressor. It is based on an optoelectronic memory that employs a complementary metal-oxide-semiconductor memory sandwiched between all-optical serial-to-parallel and photonic parallel-to-serial converters. Its optoelectronic scheme makes it possible to handle a long optical packet, and provides ultrafast burst-mode operation and flexible choice with regard to the center wavelength and/or spectral bandwidth of the output packet. We demonstrated both the 40-to-80-Gb/s compression and 40-to-10-Gb/s decompression of 32-bit optical packets.

    DOI

  • 40-Gbit/s 16-bit burst optical packet generator based on photonic parallel-to-serial conversion

    H Takenouchi, K Takahata, T Nakahara, R Takahashi, H Suzuki

    IEICE TRANSACTIONS ON ELECTRONICS   E87C ( 5 ) 825 - 827  2004.05  [Refereed]

     View Summary

    We propose a burst optical packet generator based on a novel photonic parallel-to-serial conversion scheme, and demonstrate 40-Gbit/s 16-bit optical packet generation from 16-ch parallel low-voltage TTL data streams. It consists of electrical 4:1 parallel-to-serial converters that employ InP metal-semiconductor-metal photodetectors, and an optical time-domain multiplexer with electroabsorption modulators. The proposed optical packet generator is suitable for burst optical packet generation and overcomes the electronic bandwidth limitation, which is prerequisite for achieving high-speed photonic packet switched networks. In addition, it can be driven by simple low-cost low-power CMOS logic circuits, and is compact and extensible in terms of the number of input channels due to the effective combination of electrical and optical multiplexing.

  • Photonic random access memory for 40-Gb/s 16-b burst optical packets

    R Takahashi, T Nakahara, K Takahata, H Takenouchi, T Yasui, N Kondo, H Suzuki

    IEEE PHOTONICS TECHNOLOGY LETTERS   16 ( 4 ) 1185 - 1187  2004.04  [Refereed]

     View Summary

    We present a photonic random access memory (RAM) that can write and read high-speed asynchronous burst optical packets freely by specifying addresses. The photonic RAM consists of an optical clock-pulse generator, an all-optical serial-to-parallel converter, a photonic parallel-to-serial converter, all developed by us, and a complementary metal-oxide-semiconductor RAM as a storage medium, and features large capacity, long-term storage, random access at an arbitrary timing, low power consumption, and compactness. We experimentally confirm its basic operation for 40-Gb/s 16-b optical packets.

    DOI

  • 40-Gbit/s photonic random access memory for photonic packet-switched networks

    R Takahashi, T Nakahara, K Takahata, H Takenouchi, T Yasui, N Kondo, H Suzuki

    OPTOELECTRONIC INTEGRATED CIRCUITS VI   5356   130 - 141  2004  [Refereed]  [Invited]

     View Summary

    We present a photonic random access memory (RAM) that can write and read high-speed asynchronous burst optical packets freely by specifying addresses. The photonic RAM consists of an optical clock-pulse generator, an all-optical serial-to-parallel converter, a photonic parallel-to-serial converter, all developed by us, and a CMOS RAM as a storage medium. Unlike conventional optical buffers, which merely function as optical delay lines, the photonic RAM provides various advantages, such as compactness, large capacity, long-term storage, and random access at an arbitrary timing for ultrafast asynchronous burst optical packets. We experimentally confirm its basic operation for 40-Gbit/s 16-bit optical packets.

    DOI

  • “Photonic packet router for 40-Gbit/s 16-bit burst optical packets”

    K. Takahata, R. Takahashi, T. Nakahara, H. Takenouchi, H. Suzuki

    Optical Fiber Communications Conference (OFC2004), TuQ3    2004  [Refereed]

  • “40-Gbit/s 32-bit optical packet compressor/decompressor based on a photonic memory”

    H. Takenouchi, R. Takahashi, K. Takahata, T. Nakahara, H. Suzuki

    Conference on Lasers and Electro-Optics (CLEO2004), CThQ6    2004  [Refereed]

  • “High-Speed Optical Packet Self-Routing by All-Optical Serial-to-Parallel Conversion” (Invited)

    T. Nakahara, R. Takahashi, H. Takenouchi, K. Takahata, H. Suzuki

    OptoElectronics and Communications Conference (OECC2004), 15B1-1     602 - 603  2004  [Invited]

  • "Ultrafast ptical Packet Processing Technologies Basd on Novel Hybrid Optoelectronic Devices,"

    H. Takenouchi, T. Nakahara, K. Takahata, R. Takahashi

    NTT Technical Review   2 ( 7 ) 47 - 56  2004  [Invited]

  • "Parallel-to-serial Converter Usng Metal-Semiconductor-metal Photodetector and Its Application ro Bypass/dropp Packet Switching,"

    K. Takahata, H. takenouchi, T. Nakahara, R. Takahashi

    NTT Technical Review   2 ( 7 ) 39 - 46  2004  [Invited]

  • “32-bit label swapping of 40-Gbit/s burst optical packets with intensity tracking of input label”

    T. Nakahara, H. Takenouchi, R. Takahashi, K. Takahata, H. Suzuki

    European Conference on Optical Communication (ECOC2004), Th3.6.2     938 - 939  2004  [Refereed]

  • High-speed optical packet processing technologies based on novel optoelectronic devices

    H Takenouchi, R Takahashi, K Takahata

    ACTIVE AND PASSIVE OPTICAL COMPONENTS FOR WDM COMMUNICATIONS IV   5595   277 - 290  2004  [Refereed]  [Invited]

     View Summary

    To cope with the explosive growth of IP traffic, we must increase both the link capacity between nodes and the node throughput. These requirements have stimulated research on photonic networks that use optical technologies. Optical packet switching (OPS) is an attractive solution because it maximizes the use of the network bandwidth. The key functions in achieving such networks include synchronization, label processing, compression/decompression, regeneration, and buffering for high-speed asynchronous optical packets. However, it is impractical to implement such functions by using all-optical approaches. We have proposed a new optoelectronic system composed of a packet-by-packet optical clock-pulse generator (OCG), an all-optical serial-to-parallel converter (SPC), a photonic parallel-to-serial converter (PSC), and CMOS circuitry. The OCG provides a single optical pulse synchronized with the incoming packet, and the SPC carries out a parallel conversion of the incoming packet. The parallel converted data are processed in the smart CMOS circuit, and reconstructed into an optical packet by the photonic PSC. Our system makes it possible to carry out various functions for high-speed asynchronous optical packets. This paper reviews our recent work on high-speed optical packet processing technologies such as buffering, packet compression/decompression, and label swapping, which are key technologies for constructing future OPS networks.

    DOI

  • “Ultrafast optoelectronic packet processing for asynchronous, optical-packet-switched networks” (Invited)

    R. Takahashi, T. Nakahara, K. Takahata, H. Takenouchi, T. Yasui, N. Kondo, H. Suzuki

    OSA J. Optical Networking   3 ( 12 ) 914 - 930  2004  [Invited]

  • Compact high-power photonic millimeter-wave emitter module for 60-GHz-band fiber radio links

    Y Doi, S Fukushima, K Takahata, K Yoshino, H Ito

    IEICE TRANSACTIONS ON ELECTRONICS   E86C ( 7 ) 1311 - 1317  2003.07  [Refereed]

     View Summary

    We developed compact high-power photonic millimeter-wave emitter (PME) modules for 60-GHz fiber radio links. The PME chip is a monolithic integration of a unitraveling-carrier photodiode (UTC-PD) and an antenna. One module was fabricated by attaching the chip and a plastic housing to a metal substrate, and the equivalent-isotropic radiated power (EIRP) of over 8 dBm was obtained with weak directivity of the radiated pattern. This module is suitable for point-to-multi-point communication. It is very compact, 29 x 24 x 6 mm. A module whose antenna gain was increased by attaching a dielectric lens to it was also fabricated, and the estimated EIRP of 18 dBm was obtained. This type of module is suitable for point-to-point communication and it too is compact, 29 x 24 x 17.5 mm. We achieved high-speed error-free data transmission of 1.25- and 2.5-Gbit/s phase-shift keyed (PSK) signal. The maximum distances of free-space propagation were estimated to be 18.2 and 8.9 m at bit rates of 1.25 and 2.5 Gbit/s, respectively.

  • Electrical parallel-to-serial converter using MSM-PDs for optical communication networks

    K Takahata, H Takenouchi, T Nakahara, R Takahashi, H Suzuki

    PHOTONIC INTEGRATED SYSTEMS   4998   76 - 84  2003  [Refereed]  [Invited]

     View Summary

    A new electrical parallel-to-serial converter (PSC) is proposed for optical communication networks. The PSC uses a simple circuit scheme that markedly reduces the fall time of a ordinary MSM-PD without degrading either its sensitivity or ease of fabrication. An InP-based 4:1 PSC is shown to convert 4-ch parallel electrical signals into a serial 10-Gbit/s 4-bit electrical signal when MSM-PDs in the PSC are optically triggered. It has several advantages including support of burst signal input, low driving voltage, compactness, ease of fabrication, and low power consumption. The electrical PSC is used in a new photonic PSC. By effectively combining electrical multiplexing with optical multiplexing, the photonic PSC can generate a 40-Gbit/s 16-bit optical packet from 16-ch parallel electrical signals with frame rates of 40 MHz. The electrical PSC is also applied to a label comparator for bypass/drop self-routing of optical packets. The label comparator, consisting of the 4:1 PSC and an electroabsorption modulator (EAM), properly processed 10-Gbit/s burst optical packets with no preamble even when a local address was changed at 40 MHz.

  • Electrical parallel-to-serial converter using MSM-PDs and application to bypass/drop self-routing

    K Takahata, Nakahara, I, H Takenouchi, R Takahashi, H Suzuki

    ELECTRONICS LETTERS   39 ( 1 ) 105 - 107  2003.01  [Refereed]

     View Summary

    A novel and simple electrical parallel-to-serial converter for high-speed label comparison is developed using conventional metal-semiconductor-metal photodetectors. The 1 x 2 bypass/drop self-routing of 10 Gbit/s burst optical packets is demonstrated using the 4:1 converter.

    DOI

  • “Photonic Random Access Memory Using Serial-to-Parallel and Parallel-to-Serial Conversion”

    R. Takahashi, T. Nakahara, K. Takahata, H. Takenouchi, T. Yasui, N. Kondo, H. Suzuki

    Optical Fiber Communications Conference (OFC2003), TuQ3     275 - 277  2003  [Refereed]

  • Ultrafast photonic interfaces for storage networking using serial-to-parallel and parallel-to-serial conversion

    H Suzuki, R Takahashi, T Nakahara, H Takenouchi, K Takahata, T Yasui, N Kondo, J Yumoto

    OPTICAL DATA STORAGE 2003   5069   35 - 44  2003  [Refereed]

     View Summary

    We propose novel ultrafast photonic interfaces for use in storage networking based on all-optical serial-to-parallel and photonic parallel-to-serial conversion. We confirm their operation with 40-Gbit/s 16-bit optical data using compact modules and a potential bandwidth of over 100 Gbit/s. We realize a photonic random access memory (RAM) by sandwiching a CMOS RAM with these two interfaces and achieve the storage and read-out of 40-Gbit/s 16-bit optical data. We also discuss the advantages of the interfaces and their possible applications to storage networking such as the real-time remote back-up of huge quantities of data, disaster recovery and video communication systems.

  • Ultrashort electrical pulse generation using a normal metal-semiconductor- metal photodetector

    Kiyoto Takahata, Ryo Takahashi, Tatsushi Nakahara, Hirokazu Takenouchi, Hiroyuki Suzuki

    Conference on Lasers and Electro-Optics Europe - Technical Digest     523  2003  [Refereed]

     View Summary

    In this paper, we have demonstrated the ultra-short electrical pulse generation using a normal metal-semiconductor-metal photodetector circuit (MSM-PD) at low bias voltage. The circuit using MSM-PD has much shorter fall time at the cost of repetition time and also provides high sensitivity and ease of fabrication. This circuit is very suitable for the PSC which is the key technology of photonic packet switching. © 2003 IEEE.

    DOI

  • “16-bit programmable label swapping for 40-Gbit/s optical packets”

    T. Nakahara, R. Takahashi, H. Takenouchi, K. Takahata, H. Suzuki

    European Conference on Optical Communication (ECOC2003), PDP Th4.3.6     70 - 71  2003  [Refereed]

  • “40-Gbit/s-to-10-Gbit/s Bit-rate Converter for 16-bit Optical Packets Using a Photonic RAM”

    H. Takenouchi, K. Takahata, T. Nakahara, R. Takahashi, H. Suzuki

    European Conference on Optical Communication (ECOC2003), Th3.3.4     1044 - 1045  2003  [Refereed]

  • “Photonic time-domain add-drop multiplexer for 40-Gbit/s 16-bit burst optical packets”

    K. Takahata, R. Takahashi, T. Nakahara, H. Takenouchi, H. Suzuki

    Annual Meeting of the IEEE Lasers and Electro-Optics Society (LEOS2003), PDP-1    2003  [Refereed]

  • 60-GHz monolithic photonic millimeter-wave emitter for fiber-radio applications

    K Takahata, Y Muramoto, S Fukushima, T Furuta, T Ohno, T Ishibashi, H Ito

    IEICE TRANSACTIONS ON ELECTRONICS   E85C ( 6 ) 1378 - 1380  2002.06  [Refereed]

     View Summary

    A uni-traveling-carrier refracting-facet photodiode. a short-stab bias circuit, and a patch antenna are monolithically integrated to make a compact and low-cost photonic millimeter-wave emitter for fiber-radio applications. The device emits the maximum effective radiation power of 17 +/- 3 d Bm at 60 GHz including a directive gain of the patch antenna.

  • “Photonic Parallel-to-serial Converter using MSM-PDs for Bypass/Drop Self-Routing,”

    K. Takahata, T. Nakahara, H. Takenouchi, R. Takahashi, H. Suzuki

    European Conference on Optical Communication (ECOC2002), 8.2.3   3  2002  [Refereed]

  • Compact 60-GHz photonic millimeter-wave emitter module for fiber radio link

    Y. Doi, S. Fukushima, K. Takahata, K. Yoshino, H. Ito

    2002 International Topical Meeting on Microwave Photonics, MWP 2002 - Technical Digest     65 - 68  2002  [Refereed]

     View Summary

    We developed a compact photonic emitter module for a 60 GHz fiber radio downlink with an estimated equivalent isotropically radiated power of 18 dBm. Phase-shift keyed data transmission is experimentally demonstrated at 2.5 Gbit/s.

    DOI

  • A 40-Ggbit/s 16-bit photonic parallel-to-serial converter

    H Takenouchi, K Takahata, T Nakahara, R Takahashi, H Suzuki

    2002 IEEE/LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2     45 - 46  2002  [Refereed]

  • Optically-fed radio access point module for a fibre-radio downlink system

    S Fukushima, H Fukano, K Yoshino, Y Matsuoka, S Mitachi, K Takahata

    IEICE TRANSACTIONS ON ELECTRONICS   E84C ( 2 ) 271 - 273  2001.02  [Refereed]

     View Summary

    A compact optically-fed radio access point module was developed that consists of a uni-traveling-carrier refracting-facet photodiode, a patch antenna, and an optical input interface. An output power from the photodiode was 1.4 dBm at a frequency of 5.88 GHz without any bias voltage.

  • 10-Gbit/s InP-based high-performance monolithic photoreceivers consisting of p-i-n photodiodes and HEMT's

    K Takahata, Y Muramoto, K Kato, Y Akatsu, A Kozen, Y Akahori

    IEICE TRANSACTIONS ON ELECTRONICS   E83C ( 6 ) 950 - 958  2000.06  [Refereed]

     View Summary

    10-Gbit/s monolithic receiver OEIC's for 1.55-mu m optical transmission systems were fabricated using a stacked laver structure of p-i-n photodiodes and HEMT's grown on InP substrates by single-step MOVPE. A receiver OEIC with a large O/E conversion factor was obtained by adding a three-stage differential amplifier to a conventional feedback amplifier monolithically integrated with a surface-illuminated p-i-n photodiode. The circuit configuration gave a preamplifier a transimpedance of 60 dB Omega. The receiver OEIC achieved error-free operation at 10 Gbit/s without a postamplifier even with the optical input as low as -10.3 dBm because of its large O/E conversion factor of 890V/W. A two-channel receiver OEIC array for use in a 10-Gbit/s parallel photoreceiver module based on a PLC platform was made by monolithically integrating multimode 'WGPD's with HEMT preamplifiers. The side-illuminated structure of the WGPD is suitable for integration with other waveguide-type optical devices. The receiver OEIC arrays were fabricated on a 2-inch wafer with achieving excellent uniformity and a yield over 90%: average transimpedance and average 3-dB-down bandwidth were 43.8 dB Omega and 8.0 GHz. The two channels in the receiver OEIC array also showed sensitivities of -16.1 dBm and -15.3 dBm at 10 Gbit/s. The two-channel photoreceiver module was constructed by assembling the OEIC array on a PLC platform. The frequency response of the module was almost the same as that of the OEIC chip and the crosstalk between channels in the module was better than -27dB in the frequency range below 6 GHz. These results demonstrate the feasibility of using our receiver OEIC's in various types of optical receiver systems.

  • Ultrafast monolithic receiver OEIC composed of multimode waveguide p-i-n photodiode and HEMT distributed amplifier

    K Takahata, Y Muramoto, H Fukano, K Kato, A Kozen, S Kimura, Y Imai, Y Miyamoto, O Nakajima, Y Matsuoka

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS   6 ( 1 ) 31 - 37  2000.01  [Refereed]

     View Summary

    A multimode waveguide p-i-n photodiode (WGPD) and a distributed baseband amplifier consisting of high-electron mobility transistors (HEMT's) were monolithically integrated on InP substrate using a stacked layer structure for both components. The multimode WGPD has a 3-dB bandwidth of 49 GHz. The distributed baseband amplifier has a 3-dB bandwidth of 47 GHz, though its 0.5-mu m gate-length HEMT's have modest cutoff frequencies f(T)/f(max) Of 47/100 GHz. The receiver optoelectronic integrated circuit has a bandwidth of 46.5 GHz. It was packaged into a fiber-pig-tailed module, and the WGPD in the module has a high responsivity of 0.62 A/W for 1.55-mu m wavelength. The module achieves a sensitivity of -22.7 dBm at 40 Gb/s and exhibits a clear eye-opening at 50 Gb/s.

  • Monolithically integrated millimeter-wave photonic emitter for 60-GHz fiber-radio applications

    K. Takahata, Y. Muramoto, S. Fukushima, T. Furuta, H. Ito

    International Topical Meeting on Microwave Photonics, MWP 2000   2000 ( 1 ) 229 - 232  2000  [Refereed]

     View Summary

    A uni-traveling-carrier refracting-facet photodiode, a short-stub bias circuit, and a patch antenna were monolithically integrated to make a compact and low-cost millimeter-wave photonic emitter for fiber-radio applications. The device emits the maximum effective radiation power of 17±3 dBm at 60 GHz.

    DOI CiNii

  • Characteristics of InAlAs/InGaAs high-electron-mobility transistors under illumination with modulated light

    Y Takanashi, K Takahata, Y Muramoto

    IEEE TRANSACTIONS ON ELECTRON DEVICES   46 ( 12 ) 2271 - 2277  1999.12  [Refereed]

     View Summary

    The optical response of InAlAs/InGaAs HEMT's under illumination with modulated light from a 1,3-mu m semiconductor laser diode onto the backside of the substrate is measured by using an optical-signal analyzer. It is clear that the response is composed of two signals, One signal is dominant at a low frequency and is due to the photovoltaic effect that causes excess holes photogenerated in the InGaAs channel to accumulate in the source region, This accumulation thus causes a decrease in the threshold voltage of the HEMT's. To explain this mechanism, a theory is given which connects the change in threshold voltage with that in the Fermi energy of the two-dimensional electron gas (2-DEG), The other signal is dominant at a high-frequency and is due to the photoconductive effect in the InGaAs channel beneath the gate. In this case, a large optical gain is produced since electrons at the source region are replenished in the gate channel. This leads to the first clear observation of a photoconductive signal. The bandwidth due to the photovoltaic effect is as low as 45 MHz and is dominated by the lifetime of the excess holes, The bandwidth due to the photoconductive effect is as high as 37 GHz and is dominated by the gain-bandwidth product of transistors rather than the intrinsic transit-time of electrons.

  • 52GHz bandwidth monolithically integrated WGPD/HEMT photoreceiver with large O/E conversion factor of 105V/W

    K Takahata, Y Muramoto, H Fukano, Y Matsuoka

    ELECTRONICS LETTERS   35 ( 19 ) 1639 - 1640  1999.09  [Refereed]

     View Summary

    A long-wavelength monolithic photoreceiver has been fabricated using a multimode waveguide pin photodiode and an HEMT loss-compensated distributed amplifier. It provides an O/E conversion factor of 105V/W and a 3dB-down bandwidth of 52GHz, which is the largest bandwidth for any integrated photoreceiver reported to date.

  • High efficiency edge-illuminated unitravelling-carrier-structure refracting-facet photodiode

    H Fukano, Y Muramoto, K Takahata, Y Matsuoka

    ELECTRONICS LETTERS   35 ( 19 ) 1664 - 1665  1999.09  [Refereed]

     View Summary

    A high-efficiency uni-travelling carrier (UTC) photodiode has been developed which employs an edge-illuminated refracting-facet photodiode (RFPD) structure. The fabricated UTC-RFPD shows a maximum responsivity of 0.48A/W even with an absorption layer as thin as 2808nm, and a high output peak-to-peak voltage of 1.5V at 40Gbit/s.

  • Ultrafast monolithic receiver OEIC module operating at over 40 Gbit/s

    K Takahata, Y Miyamoto, Y Muramoto, H Fukano, Y Matsuoka

    ELECTRONICS LETTERS   35 ( 4 ) 322 - 324  1999.02  [Refereed]

     View Summary

    A high-speed monolithic receiver, consisting of a waveguide pin photodiode and an HEMT distributed amplifier, was packaged in a fibre-pigtailed module. It achieved a sensitivity of -22.7 dBm at 40 Gbit/s and a clear eye-opening at 50 Gbit/s. Such a performance is a first for a monolithic photoreceiver module.

  • “40-Gbit/s WGPD/HEMT monolithic photoreceiver with output voltage of 1 Vp-p”

    K. Takahata, Y. Muramoto, H. Fukano, Y. Matsuoka

    OptoElectronics and Communications Conference (OECC'99)   2   1657 - 1659  1999  [Refereed]

  • Characteristics of InAlAs/InGaAs high electron mobility transistors under 1.3-mu m laser illumination

    Y Takanashi, K Takahata, Y Muramoto

    IEEE ELECTRON DEVICE LETTERS   19 ( 12 ) 472 - 474  1998.12  [Refereed]

     View Summary

    The current-voltage (I-V) characteristics of InAlAs/InGaAs high electron mobility transistors (HEMT's) under illumination are investigated. The change of the drain current caused by the illumination can be explained by using the photovoltaic effect so that the excess holes photo-generated in the InGaAs channel lager accumulate at the source-electrode region and cause an effective decrease in the potential barrier for electrons between the source and the channel, The basic equations describing this phenomenon are derived on the basis of the experimental results. In addition, our experimental results are shown to support the barrier-induced hole pile-up model in which holes generated by the impact ionization accumulate in the InAlAs barrier on the source side and cause the kink effect in InAlAs/InGaAs HEMT's.

  • 46.5-GHz-bandwidth monolithic receiver OEIC consisting of a waveguide p-i-n photodiode and a HEMT distributed amplifier

    K Takahata, Y Muramoto, H Fukano, K Kato, A Kozen, O Nakajima, Y Matsuoka

    IEEE PHOTONICS TECHNOLOGY LETTERS   10 ( 8 ) 1150 - 1152  1998.08  [Refereed]

     View Summary

    A large bandwidth monolithically integrated photoreceiver for 1.55-mu m wavelength operation was fabricated using a stacked structure of waveguide p-i-n photodiode layers and InAlAs-InGaAs high-electron mobility transistor (HEMT) layers grown using a single-step metal-organic vapor-phase epitaxy. The monolithic receiver optoelectronic integrated circuit (OEIC) consists of a waveguide p-i-n photodiode with a high responsivity of 0.5 A/W and a HEMT distributed amplifier. It has a bandwidth of 46.5 GHz, which is the largest yet reported for a long-wavelength receiver OEIC, and exhibits a clear eye opening at 40 Gb/s. This excellent performance is very attractive for use in high-speed optical transmission systems and millimeter-wave fiber-radio systems.

  • “High-performance Monolithically Integrated pin/HEMT Photoreceiver” (Invited)

    K. Takahata, Y. Muramoto, H. Fukano, K. Kato

    OptoElectronics and Communications Conference (OECC'98), 14B3-1     132 - 133  1998  [Invited]

  • 50-Gbit/s operation of monolithic WGPD/HEMT receiver OEIC module

    K Takahata, Y Miyamoto, Y Muramoto, H Fukano, Y Matsuoka

    24TH EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION, VOL 1-3   3   B67 - B69  1998  [Refereed]

     View Summary

    A monolithic photoreceiver module using a waveguide p-i-n photodiode/HEMT-distributed-amplifier OEIC has been developed. It achieves a sensitivity of -22.7 dBm at 40 Gbit/s and a clear eye-opening at 50 Gbit/s. Such performance is a first for a monolithic photoreceiver module.

  • 20Gbit/s monolithic photoreceiver consisting of a waveguide pin photodiode and HEMT distributed amplifier

    K Takahata, Y Muramoto, H Fukano, K Kato, A Kozen, O Nakajima, S Kimura, Y Imai

    ELECTRONICS LETTERS   33 ( 18 ) 1576 - 1577  1997.08  [Refereed]

     View Summary

    A monolithic photoreceiver OEIC for lambda = 1.55 mu m consisting of a waveguide pin photodiode and an InAlAs/InGaAs HEMT distributed amplifier has been fabricated using a single-step MOVPE growth technique. It has a 3dB-down frequency of 2OGHz and operates at 20Gbit/s with a sensitivity of -10.4dBm.

  • “30-Gbit/s Monolithic Photoreceiver Consisting of a Waveguide p-i-n Photodiode and a Distributed Amprifier”

    K. Takahata, Y. Muramoto, H. Fukano, K. Kato, A. Kozen, K. Noguchi, O. Nakajima, S. Kimura, Y. Imai

    European Conference on Integrated Optics (ECIO'97), EFB4     538 - 541  1997  [Refereed]

  • “High speed receiver OEICs using waveguide pin photodiodes and HEMTs” (Invited)

    K. Takahata

    IEEE MTT-S International Microwave Symposium (IMS'97), WMB (Workshop)    1997  [Invited]

  • 46.5-GHz-bandwidth monolithic receiver OEIC consisting of a waveguide pin photodiode and a distributed amplifier

    Y Muramoto, K Takahata, H Fukano, K Kato, A Kozen, O Nakajima, Y Matsuoka

    IOOC-ECOC 97 - 11TH INTERNATIONAL CONFERENCE ON INTEGRATED OPTICS AND OPTICAL FIBRE COMMUNICATIONS / 23RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATIONS, VOL 5   5 ( 448 ) 37 - 40  1997  [Refereed]

     View Summary

    A monolithic receiver OEIC with a record bandwidth of 46.5 GHz is described, It consists of a waveguide p-i-n photodiode with a high responsivity of 0.5 A/W and a HEMT distributed amplifier. A fabricated OEIC operates at 40 Gbit/s with a clear eye opening.

  • 10-Gb/s two-channel monolithic photoreceiver array using waveguide p-i-n PD's and HEMT's

    K Takahata, Y Muramoto, Y Akatsu, Y Akahori, A Kozen, Y Itaya

    IEEE PHOTONICS TECHNOLOGY LETTERS   8 ( 4 ) 563 - 565  1996.04  [Refereed]

     View Summary

    Two-channel side-illuminated receiver OEIC arrays comprising waveguide p-i-n photodiodes and InAlAs-InGaAs-HEMT transimpedance amplifiers were fabricated with good uniformity on a 2-in wafer. The performances of the two channels were measured by on-wafer probe measurements and showed well-matched 3-dB bandwidth of 8.0 GHz, transimpedance of 155 Omega, and crosstalk less than -20 dB, The OEIC array operates at 10 Gbit/s with sensitivities of -16.1 dBm and -15.3 dBm for each channel for a bit error rate of 10(-9) at a wavelength of 1.55 mu m This is the highest bit rate yet reported for a long-wavelength monolithic photoreceiver array.

  • Broad-range tunable wavelength conversion of high-bit-rate signals using super structure grating distributed Bragg reflector lasers

    H Yasaka, H Ishii, K Takahata, K Oe, Y Yoshikuni, H Tsuchiya

    IEEE JOURNAL OF QUANTUM ELECTRONICS   32 ( 3 ) 463 - 470  1996.03  [Refereed]

     View Summary

    Tunable wavelength conversion of a 10 Gb/s signal over a broad wavelength range of about 90 nm is achieved by using a super structure grating distributed Bragg reflector laser. The extinction ratio dependence of converted signal light on input signal light power and bias current to the laser active region is discussed. The extinction ratio becomes large when the input signal light power increases and the bias current decreases. Bit error rate measurements shaw that error-free, penalty-free wavelength conversion is achieved when the extinction ratio is large (12.5 dB) and that the bit rate which error-free wavelength conversion is possible increases as the input signal light power increases. Twenty Gb/s signal wavelength conversion is also demonstrated.

  • Analysis and application of a novel model for estimating power dissipation of optical interconnections as a function of transmission bit error rate

    M Yoneyama, K Takahata, T Otsuji, Y Akazawa

    JOURNAL OF LIGHTWAVE TECHNOLOGY   14 ( 1 ) 13 - 22  1996.01  [Refereed]

     View Summary

    This paper proposes a novel model for estimating power dissipation of optical/electrical interconnections as a function of transmission bit error rate. This model is applied to a simplified optoelectronic transmitter and receiver configuration in which a photodetector is directly connected to the decision circuit. It is analytically verified that this configuration can achieve error-free operation with low power under practical operating conditions. A comparison between optical and electrical interconnections based on this simplified configuration is performed. This result shows the interconnection length and bit rate at which optical interconnection is superior in terms of power dissipation to electrical interconnection. Only optical interconnections achieve error-free operation with 40 mW power dissipation at a transmission bit rate of 10 Gb/s and an interconnection length over 7 m.

  • HIGH-SPEED SIGNAL WAVELENGTH CONVERSION USING A UNIDIRECTIONAL-OUTPUT WAVELENGTH CONVERSION DEVICE WITH ASYMMETRIC-KAPPA DBR STRUCTURE

    H YASAKA, K TAKAHATA, K OE

    IEEE JOURNAL OF QUANTUM ELECTRONICS   31 ( 1 ) 82 - 91  1995.01  [Refereed]

     View Summary

    The wavelength conversion device whose frequency response is evaluated analytically and experimentally in this work has a saturable absorber region, which acts as an optical gate, within the active region. The 3-dB bandwidth of this device was measured to be 800 MHz and found to be limited by the frequency response of the saturable absorber region. To speed up this device, the electrodes of the saturable absorber and the gain regions were connected electrically so that the device would act as a unidirectional-output distributed Bragg reflector (DBR) laser. When the active region (saturable absorber and the gain regions) of this DBR laser were biased above threshold condition, the 3-dB bandwidth was more than 10 GHz, and clear eye patterns were observed when the input TM-polarized light intensity was modulated by a 10-Gbit/s pseudo-random NRZ signal. These results show that high-speed wavelength conversion can be achieved when the device is operated as a laser diode.

  • “A 10-Gbit/s Monolithically Integrated Long-Wavelength Two-Channel Photoreceiver Array using Waveguide p-i-n PDs and HEMTs”

    K. Takahata, Y. Muramoto, Y. Akatsu, Y. Akahori, A. Kozen, Y. Itaya

    Integrated Photonics Research (IPR'95), IThA1   95 ( 156 ) 6 - 8  1995  [Refereed]

     View Summary

    Two-channel receiver OEIC arrays comprising waveguide p-i-n photodiodes and transimpedance amplifiers have been fabricated on 2-inch wafer with god uniformity. Two channels show well matched 3-dB bandwidth of 8.0GHz and crosstalk less than -20dB with on-wafer-probe measurements. The OEIC array operates at 10Gbit/s with a sensitivity of -16.1dBm and -15.3dBm for each channel for a bit error rate of 10^<-9>. This is the highest-bit-rate demonstration yet reported for a longwavelength monolithic photoreceiver array.

    CiNii

  • A UNIDIRECTIONAL OUTPUT OPTICAL FREQUENCY-CONVERSION DEVICE WITH AN ASYMMETRIC-KAPPA DBR STRUCTURE

    K TAKAHATA, K KASAYA, H YASAKA, Y KONDO, M IKEDA

    IEEE JOURNAL OF QUANTUM ELECTRONICS   30 ( 5 ) 1219 - 1226  1994.05  [Refereed]

     View Summary

    A novel optical frequency conversion device that successfully demonstrates optical frequency conversion and unidirectional transmission of optical signals has been designed and fabricated. The device is composed of a gain region and saturable absorber region with monolithically integrated distributed Bragg reflector (DBR) mirrors with different coupling coefficients. The device structure is optimized to achieve three functions: 1) unidirectional light output, 2) converted-light wavelength tuning, and 3) optically triggered optical frequency conversion. The output power of converted light from the light input-end facet of the device is 30 dB smaller than that from the output-end racet, and the converted light wavelength can be scanned over 4 nm without a bias current to the input-end DBR region, and it is widened to 7.8 nm by injecting current to that region. The device emits converted light only when light input is injected and optical signals are unidirectionally transmitted, and its response frequency is estimated to be 0.8 GHz.

  • BREAD-RANGE WAVELENGTH CONVERSION OF 10GBIT/S SIGNAL USING A SUPERSTRUCTURE GRATING DISTRIBUTED-BRAGG-REFLECTOR LASER

    H YASAKA, H ISHII, K TAKAHATA, K OE, Y YOSHIKUNI, H TSUCHIYA

    ELECTRONICS LETTERS   30 ( 2 ) 133 - 134  1994.01  [Refereed]

     View Summary

    The authors report the tunable wavelength conversion of a 10Gbit/s signal over a broad wavelength range of similar to 90nm using a superstructure grating distributed Bragg reflector (DBR) laser.

  • FREQUENCY-RESPONSE OF A UNIDIRECTIONAL-OUTPUT OPTICAL FREQUENCY-CONVERSION DEVICE WITH AN ASYMMETRICAL-KAPPA DBR LASER STRUCTURE

    H YASAKA, K TAKAHATA, K KASAYA, K OE

    IEEE PHOTONICS TECHNOLOGY LETTERS   5 ( 11 ) 1306 - 1310  1993.11  [Refereed]

     View Summary

    The frequency response of a unidirectional-output optical frequency conversion device is measured. The device has a saturable absorber region within the active region, which acts as an optical gate for converted light. The 3-dB bandwidth of the device with saturable absorber region is measured to be 800 MHz, and is found to be limited by the frequency response of the saturable absorber region.
    To operate the device faster, lasing mode intensity modulation by input light is attempted by using the device in a laser diode mode. In this case, the electrodes of the saturable absorber and the gain regions are connected electrically, and the saturable absorber region is also biased far above the threshold condition at the same time with the gain region. The 3-dB bandwidth of the device increases to over 10 GHz, and the 10 Gb/s nonreturn-to-zero (NRZ) eye pattern can be observed when the input TM-polarized light intensity is modulated by a 10 Gb/s NRZ pseudo-random signal.

  • OPTICAL FREQUENCY-CONVERSION DEVICE WITH ASYMMETRIC KAPPA-DBR STRUCTURE

    K KASAYA, K TAKAHATA, H YASAKA

    IEEE PHOTONICS TECHNOLOGY LETTERS   5 ( 3 ) 321 - 324  1993.03  [Refereed]

     View Summary

    An optical-frequency conversion device is fabricated, using monolithically integrated distributed Bragg reflector (DBR) mirrors with different coupling coefficients at the outer sides of the active and the saturable absorber regions. The input-end DBR mirror has higher coupling coefficient than that of the output-end DBR mirror. The converted light is reflected by the input-end DBR mirror and is emitted only from the output end of the device. This device successfully performs optical frequency conversion when the input TM-polarized light has a wavelength within the wavelength range for which the reflection of the input-end DBR mirror is fairly high for TE-polarized light. The ratio of the converted-light output power for TE-polarized light from the input end to that from the output end is less than -30 dB.

  • NONLINEAR ION BERNSTEIN WAVE HEATING EXPERIMENT IN THE WT-3 TOKAMAK

    Y YASAKA, H TAKENO, M SAKKA, O SAKAI, R ITATANI, T FUJIMOTO, H SUEMITSU, K TAKAHATA, M FUKAO, S TANAKA, Y TERUMICHI

    PLASMA PHYSICS AND CONTROLLED FUSION   35 ( 3 ) 379 - 389  1993.03  [Refereed]

     View Summary

    Ion Bernstein wave (IBW) heating at ion cyclotron half-harmonic frequencies was performed in hydrogen (H) discharges in the WT-3 tokamak. The bulk ion temperature increase was measured by a charge exchange analyser and a spatially scanning polychrometer. The latter diagnostics can provide radial ion-temperature profiles. The incremental ion temperature has shown a peak at the exact location where the IBW frequency omega equals 3/2 of the ion cyclotron frequency, indicating the nonlinear direct acceleration of H ions. The wave electric field was measured by a Langmuir probe in the scrape-off layer. The electric field at the second harmonic of the excited IBW frequency was observed to vary depending on the power level and the toroidal magnetic field. These experimental results are compared with the theoretical prediction of nonlinear IBW damping. The measured dependences of the ion heating and the wave amplitude at 2omega on the toroidal magnetic field are in reasonable agreement with the prediction.

  • WAVELENGTH DEPENDENCE OF OPTICAL FREQUENCY-CONVERSION DEVICE WITH ASYMMETRIC KAPPA-DBR STRUCTURE

    K TAKAHATA, K KASAYA, H YASAKA

    ELECTRONICS LETTERS   28 ( 22 ) 2078 - 2079  1992.10  [Refereed]

     View Summary

    Wavelength dependence was measured for a one-directional output optical frequency conversion device that has an asymmetric-coupling-coefficient (kappa) distributed-Bragg-reflector (DBR) structure. The output power of converted light from the light input end is 30 dB smaller than that from the output end. The injected light wavelength and polarisation dependence of converted light power has also been investigated. The converted light wavelength scanning range is confirmed to be the design value of 4 nm, which is the widest ever reported.

  • SPECTRAL LINEWIDTH OF MQW DFB LASERS WITH INTENSITY-MODULATED TM-POLARIZED LIGHT INJECTION

    H YASAKA, K KASAYA, K TAKAHATA, M NAGANUMA

    IEEE PHOTONICS TECHNOLOGY LETTERS   4 ( 7 ) 679 - 682  1992.07  [Refereed]

     View Summary

    The spectral linewidth of a multiple-quantum-well (MQW) distributed feedback (DFB) laser is measured when intensity-modulated orthogonally-polarized (transverse magnetic (TM) mode) light is injected into the laser. The spectral linewidth does not change when the modulation frequency is higher than several hundred megahertz and is almost the same as without light injection. However, it broadens when the injected orthogonally polarized light modulation frequency is close to zero. The line shape of the MQW DFB laser's lasing light becomes non-Lorentzian in shape below a modulation frequency of 500 MHz.

  • MEASUREMENT OF GAIN SATURATION COEFFICIENTS IN STRAINED-LAYER MULTIPLE QUANTUM-WELL DISTRIBUTED FEEDBACK LASERS

    H YASAKA, K TAKAHATA, M NAGANUMA

    IEEE JOURNAL OF QUANTUM ELECTRONICS   28 ( 5 ) 1294 - 1304  1992.05  [Refereed]

     View Summary

    Gain saturation coefficients of unstrained- and strained-layer multiple quantum-well lasers were measured experimentally. These coefficients were higher in lasers that had compressive strain in their active-layer wells: 2.45 x 10(-17) cm3 with unstrained wells and 12.6 x 10(-17) cm3 with strained wells. The higher gain saturation coefficient in lasers with strained active-layer wells is related to their higher linear TE mode gain coefficient. The linearity factor (K factor) between a laser's damping constant and the square of the laser's resonant frequency decreased slightly with introducing the strain in laser's active layer wells. This factor, however, took the value of about 0.2 x 10(-9) s for each of these lasers. The a parameter of these lasers was also estimated: 3.1 for an unstrained-layer multiple quantum-well laser and 1.1 for a laser with compressive strain in the active-layer wells.

  • "One-directional output optical frequency conversion device with asymmetric k-structure"

    H. Yasaka, K. Takahata, K. Kasaya, M. Okamoto, Y. Kondo, M. Naganuma, M. Ikeda

    European Conference on Optical Communication (ECOC'92), WeA10.5    1992  [Refereed]

  • GAIN SATURATION COEFFICIENTS OF STRAINED-LAYER MULTIPLE QUANTUM-WELL DISTRIBUTED FEEDBACK LASERS

    H YASAKA, K TAKAHATA, N YAMAMOTO, M NAGANUMA

    IEEE PHOTONICS TECHNOLOGY LETTERS   3 ( 10 ) 879 - 882  1991.10  [Refereed]

     View Summary

    The gain saturation coefficients are measured for strained and unstrained multiple quantum-well distributed feedback lasers. The gain saturation coefficient depends on the deviation of the laser's TM mode gain peak wavelength from its TE mode gain peak wavelength delta-lambda, which is concerned with the strain on the active-layer wells. It is also found that the gain saturation coefficient increases with strain on the active-layer wells.

  • RADIAL-DISTRIBUTION OF ION TEMPERATURE IN A WT-III TOKAMAK PLASMA, AS DETERMINED FROM ABEL INVERSION OF IMPURITY LINE-PROFILES

    S MIYACHI, K SAWADA, K TAKAHATA, H SUEMITSU, T FUJIMOTO, R OKASAKA, K ISHII, Y HIRATA, M FUKAO, H TANAKA, T MAEKAWA, Y TERUMICHI, S TAKAKA

    JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER   42 ( 5 ) 355 - 357  1989.11  [Refereed]

  • RATIO OF BALMER LINE-INTENSITIES RESULTING FROM DISSOCIATIVE EXCITATION OF MOLECULAR-HYDROGEN IN AN IONIZING PLASMA

    T FUJIMOTO, K SAWADA, K TAKAHATA

    JOURNAL OF APPLIED PHYSICS   66 ( 6 ) 2315 - 2319  1989.09  [Refereed]

  • SPECTROSCOPIC DETERMINATION OF HYDROGEN AND ELECTRON-DENSITIES IN PLASMA IN THE IONIZING PHASE - APPLICATION TO WT-III

    T FUJIMOTO, K SAWADA, K TAKAHATA, K ERIGUCHI, H SUEMITSU, K ISHII, R OKASAKA, H TANAKA, T MAEKAWA, Y TERUMICHI, S TANAKA

    NUCLEAR FUSION   29 ( 9 ) 1519 - 1521  1989.09  [Refereed]

  • Numerical transport studies for the CASTOR tokamak

    T. Fujimoto, K. Sawada, K. Takahata, K. Eriguchi, H. Suemitsu, K. Ishii, R. Okasaka, H. Tanaka, T. Maekawa, Y. Terumichi, S. Tanaka

    Nuclear Fusion   29 ( 9 ) 1519 - 1521  1989  [Refereed]

     View Summary

    The Balmer line intensities of atomic hydrogen from the WT-III tokamak plasma have been observed and interpreted in terms of the collisional-radiative model. The atomic and molecular hydrogen densities are deduced together with the electron density. Going from the plasma centre to the edge region along the minor radius, the atomic hydrogen density increases slightly and molecular hydrogen is found only in the periphery. In the edge region, the atomic hydrogen density reaches 1 × 1016 m−3 and the molecular hydrogen density 4 × 10l7 m−3The electron density distribution is consistent with that determined by infrared laser interferometry. © 1989 IOP Publishing Ltd.

    DOI

▼display all

Books and Other Publications

  • 「電源不要な超小型光マイクロ波変換モジュール」月間EMC (2000年12月号)

    髙畑 清人, 福島 誠治, 三田地 成幸

    科学情報出版  2000.12

Misc

  • C-3-44 Study of Optical Butt-coupling Improvement between Silica-based Planar Lightwave Circuit and Spot-size Convertor Integrated Laser

    Takahata Kiyoto, Ohyama Takaharu, Kobayashi Wataru, Doi Yoshiyuki, Sanjoh Hiroaki, Hashimoto Toshikazu

    Proceedings of the IEICE General Conference   2016 ( 1 ) 182 - 182  2016.03

    CiNii

  • C-4-15 4チャネル直接変調DFBレ-ザアレイTOSAの100Gbit/s動作(C-4.レ-ザ・量子エレクトロニクス,一般セッション)

    Kanazawa S., Kobayashi W., Takahata K., Ishii H., Sanjoh H.

    Proceedings of the IEICE General Conference   2016 ( 1 ) 219 - 219  2016.03

    CiNii

  • C-4-14 Frequency response flattening of EADFB laser module using flip-chip interconnects

    Kanazawa S., Ueda Y., Takahata K., Ishii H., Sanjoh H.

    Proceedings of the Society Conference of IEICE   2015 ( 1 ) 151 - 151  2015.08

    CiNii

  • C-3-45 100Gbit/s TOSA using optical butt-coupling between LD array and AWG

    Ohyama T., Doi Y., Kobayashi W., Kanazawa S., Takahata K., Kanda A., Kurosaki T., Tanaka T., Ohno T., Sanjoh H., Hashimoto T.

    Proceedings of the Society Conference of IEICE   2015 ( 1 ) 119 - 119  2015.08

    CiNii

  • C-3-55 Study of Multi-lane Optical System using Butt-coupling between Silica-based Planar Lightwave Circuit and Laser-diode with Spot-size Convertor

    Ohyama Takaharu, Doi Yoshiyuki, Kobayashi Wataru, Tanaka Takuya, Kanazawa Sigeru, Takahata Kiyoto, Sanjoh Hiroaki, Hashimoto Toshikazu

    Proceedings of the IEICE General Conference   2015 ( 1 ) 179 - 179  2015.02

    CiNii

  • 8 x 50-Gb/s EADFB laser array module using flip-chip interconnection technique

    KANAZAWA Shigeru, FUJISAWA Takeshi, TAKAHATA Kiyoto, SANJOH Hiroaki, IGA Ryuzo, ISHII Hiroyuki

    Technical report of IEICE. OCS   114 ( 281 ) 211 - 214  2014.10

     View Summary

    We developed the first flip-chip interconnection EADFB laser array module for 400G system. The flip-chip interconnection technique yields lower crosstalk and higher modulation bandwidth compared to conventional wire interconnection technique. With flip-chip interconnection module, there was no rapid degradation of the E/O response under 35 GHz. And after 10-km transmission, the clear eye openings for all eight lanes were observed under 8-channel simultaneous operation.

    CiNii

  • Low-voltage Operation of Mach-Zehnder Interferometer-type Electroabsorption Modulator integrated with DFB Laser Diode

    UEDA Yuta, FUJISAWA Takeshi, KANAZAWA Shigeru, KOBAYSHI Wataru, TAKAHATA Kiyoto, SANJOH Hiroaki, ISHII Hiroyuki, Kohtoku Masaki

    Technical report of IEICE. OCS   114 ( 281 ) 153 - 157  2014.10

     View Summary

    An electroabsorption modulator (EAM) integrated with a laser diode is key device of a low-power consumption and low cost optical transmitter for middle-distance optical communication. Reduction of the modulation voltage (V_m) of an EAM is an important issue to further reduce the power consumption of the transmitter. We have developed an Mach-Zenhder (MZ) interferometer-type EAM (MZEA) that has large extinction ratio (ER) since it modulates the light intensity by both optical absorption and interferometric extinction, resulting in low-voltage operation for a given ER. Furthermore, we integrated the MZEA with a DFB laser diode and obtained low V_m operation with comparable output power to a conventional EAM integrated with a DFB laser diode.

    CiNii

  • C-4-1 50 Gb/s x 8Ch operation with EADFB laser array module using flip-chip interconnects

    Kanazawa S, Fujisawa T, Takahata K, Sanjoh H, Iga Ryuzo, Ishii H

    Proceedings of the Society Conference of IEICE   2014 ( 1 ) 155 - 155  2014.09

    CiNii

  • C-4-7 Very-Low-Voltage Operation of Mach-Zehnder Interferometer-Type Electroabsorption Modulator using Optical Absorption and Interferometric Extinction

    Ueda Yuta, Fujisawa Takeshi, Kanazawa Shigeru, Kobayashi Wataru, Takahata Kiyoto, Sanjoh Hiroaki, Ishii Hiroyuki

    Proceedings of the Society Conference of IEICE   2014 ( 1 ) 161 - 161  2014.09

    CiNii

  • C-4-7 Very-Low-Voltage Operation of Mach-Zehnder Interferometer-Type Electroabsorption Modulator with Asymmetric Couplers

    Ueda Y., Fujisawa T., Kanazawa S., Kobayashi W, Takahata K., Ishii H.

    Proceedings of the IEICE General Conference   2014 ( 1 ) 243 - 243  2014.03

    CiNii

  • An electroabsorption modulator integrated DFB laser array integrated with low-loss optical multiplexer for 100GbE

    Fujisawa Takeshi, Kanazawa Shigeru, Ueda Yuta, Kobayashi Wataru, Takahata Kiyoto, Ohki Akira, Itoh Toshio, Kohtoku Masaki, Ishii Hiroyuki

    Technical report of IEICE. LQE   113 ( 395 ) 135 - 140  2014.01

     View Summary

    A 4×25-Gb/s electroabsorption modulator integrated with a distributed feedback laser (EADFB laser) array monolithically integrated with a low-loss optical multiplexer (MUX) is developed for 100GbE transmitters. A cascaded Mach-Zehnder (MZ) filter, which has no intrinsic loss, is used as the MUX. The measured loss of fabricated MZ-MUX is 2 to 3dB, which is improved by 4dB compared with that of the conventional 1×4 multimode interference (MMI) MUX. The MZ-MUX is monolithically integrated with a four-EADFB-laser array and the output power of the chip is increased. With the folded layout, the size of the chip is similar to that of the conventional chip. The fabricated chip is packaged into a very compact TOSA. The system requirements are satisfied with semi-cooled operation, and very clear eye openings are obtained after 10-km single-mode-fiber (SMF) transmission. The adjustment of filter spectra by current injection is also shown, and fine tuning is possible with very low injection current.

    CiNii

  • An electroabsorption modulator integrated DFB laser array integrated with low-loss optical multiplexer for 100GbE

    Fujisawa Takeshi, Kanazawa Shigeru, Ueda Yuta, Kobayashi Wataru, Takahata Kiyoto, Ohki Akira, Itoh Toshio, Kohtoku Masaki, Ishii Hiroyuki

      113 ( 396 ) 135 - 140  2014.01

     View Summary

    A 4×25-Gb/s electroabsorption modulator integrated with a distributed feedback laser (EADFB laser) array monolithically integrated with a low-loss optical multiplexer (MUX) is developed for 100GbE transmitters. A cascaded Mach-Zehnder (MZ) filter, which has no intrinsic loss, is used as the MUX. The measured loss of fabricated MZ-MUX is 2 to 3dB, which is improved by 4dB compared with that of the conventional 1×4 multimode interference (MMI) MUX. The MZ-MUX is monolithically integrated with a four-EADFB-laser array and the output power of the chip is increased. With the folded layout, the size of the chip is similar to that of the conventional chip. The fabricated chip is packaged into a very compact TOSA. The system requirements are satisfied with semi-cooled operation, and very clear eye openings are obtained after 10-km single-mode-fiber (SMF) transmission. The adjustment of filter spectra by current injection is also shown, and fine tuning is possible with very low injection current.

    CiNii

  • An electroabsorption modulator integrated DFB laser array integrated with low-loss optical multiplexer for 100GbE

    Fujisawa Takeshi, Kanazawa Shigeru, Ueda Yuta, Kobayashi Wataru, Takahata Kiyoto, Ohki Akira, Itoh Toshio, Kohtoku Masaki, Ishii Hiroyuki

      113 ( 397 ) 135 - 140  2014.01

     View Summary

    A 4×25-Gb/s electroabsorption modulator integrated with a distributed feedback laser (EADFB laser) array monolithically integrated with a low-loss optical multiplexer (MUX) is developed for 100GbE transmitters. A cascaded Mach-Zehnder (MZ) filter, which has no intrinsic loss, is used as the MUX. The measured loss of fabricated MZ-MUX is 2 to 3dB, which is improved by 4dB compared with that of the conventional 1×4 multimode interference (MMI) MUX. The MZ-MUX is monolithically integrated with a four-EADFB-laser array and the output power of the chip is increased. With the folded layout, the size of the chip is similar to that of the conventional chip. The fabricated chip is packaged into a very compact TOSA. The system requirements are satisfied with semi-cooled operation, and very clear eye openings are obtained after 10-km single-mode-fiber (SMF) transmission. The adjustment of filter spectra by current injection is also shown, and fine tuning is possible with very low injection current.

    CiNii

  • 100GbE transmitter optical sub-assembly (TOSA) using polarization multiplexing

    Ohyama Takaharu, Ohki Akira, Takahata Kiyoto, Ito Toshio, Nunoya Nobuhiro, Fujisawa Takeshi, Kanazawa Shigeru, Iga Ryuzo, Sanjoh Hiroaki

    Technical report of IEICE. LQE   113 ( 264 ) 75 - 80  2013.10

     View Summary

    We have developed a compact transmitter optical sub-assembly (TOSA) for a 100Gbit/s Ethernet system with a long transmission distance of 40 km over single-mode fiber. The TOSA consists of two electro-absorption modulator integrated distributed feedback laser diode arrays with a wavelength channel spacing of 800 GHz in the 1.3μm wavelength band and a polarization beam combiner for wavelength multiplexing to realize a high optical output power. As a result, the optical output power was around 2 dB higher than our previous TOSA. We also confirmed that the TOSA successfully achieved an error-free four-lane×25.8 Gbit/s transmission, i.e. a total bit rate of 100 Gbit/s, over 40 km, which shows that the TOSA complies with the requirement for 100GBASE-ER4.

    CiNii

  • InP-based reflection-type transversal filter for compact multiplexer of array-type monolithically integrated light source

    Ueda Y, Fujisawa T, Takahata K, Kohtoku M, Ishii H

    Proceedings of the Society Conference of IEICE   2013 ( 1 ) 171 - 171  2013.09

    CiNii

  • Compact 100GbE Transmitter Optical Sub-Assembly using Polarization Multiplexing

    Ohyama T, Ohki A, Takahata K, Ito T, Nunoya N, Fujisawa T, Kanazawa S, Iga R, Sanjoh H

    Proceedings of the Society Conference of IEICE   2013 ( 1 ) 221 - 221  2013.09

    CiNii

  • 28Gbit/s X 4Ch operation with EADFB laser array module using flip-chip interconnects

    Kanazawa S, Fujisawa T, Takahata K, Ohki A, Iga R, Ishii H

    Proceedings of the Society Conference of IEICE   2013 ( 1 ) 222 - 222  2013.09

    CiNii

  • Low-crosstalk and high-modulation bandwidth operation of flip-chip interconnection EADFB laser array module

    KANAZAWA Shigeru, FUJISAWA Takeshi, TAKAHATA Kiyoto, OHKI Akira, IGA Ryuzo, ISHII Hiroyuki

    IEICE technical report. Component parts and materials   113 ( 188 ) 31 - 34  2013.08

     View Summary

    We developed the first EADFB laser array module with new flip-chip interconnects which provide low crosstalk and high modulation bandwidth. Under four-channel simultaneous operation, the 100GBASE-LR4 mask margin of the flip-chip interconnection module was improved up to 24% compared with that of a wire interconnection module.

    CiNii

  • C-10-10 A study of pre-emphasis circuit for 28-Gbit/s-class driver IC

    Wakita Hitoshi, Nakamura Makoto, Fukuyama Hiroyuki, Tsunashima Satoshi, Kurishima Kenji, Kanazawa Shigeru, Fujisawa Tsuyoshi, Takahata Kiyoto

    Proceedings of the IEICE General Conference   2013 ( 2 ) 70 - 70  2013.03

    CiNii

  • An electroabsorption modulator integrated DFB laser for beyond 100G parallel LAN applications

    FUJISAWA Takeshi, KANAZAWA Shigeru, TAKAHATA Kiyoto, OHKI Akira, UEDA Yuta, KOBAYASHI Wataru, IGA Ryuzo, SANJI Hiroaki, KOTOKU Masaki, ISHII Hiroyuki

    Technical report of IEICE. OPE   112 ( 259 ) 97 - 101  2012.10

     View Summary

    In 100GbE, a multi-lane LAN-WDM system, in which four 25-Gbit/s light sources with different waveglengths are used for the transmitter, was employed. For beyond 100G LAN applications, it is almost unavoidable to use multi-lane system. At the same time, increasing the data rate of serial lanes is also a very important for reducing the number of lanes and the whole size of the transmitter. Here, we developed 1.3-um EADFB lasers with the modulation speed of over 25-Gbit/s for beyond 100G parallel LAN applications. The EADFB lasers developed here can be operated at the modulation speed of 50-Gibt/s and we obtained very clear eye openings up to 40-km transmission with semi-cooled operation (45 degree Celcius). Furthermore, we fabricated a monolithically integrated light source by integrating four these EADFB lasers and developed an ultracompact TOSA. By using the TOSA, 40-Gbit/s operation per channel was confirmed.

    CiNii

  • An electroabsorption modulator integrated DFB laser for beyond 100G parallel LAN applications

    FUJISAWA Takeshi, KANAZAWA Shigeru, TAKAHATA Kiyoto, OHKI Akira, UEDA Yuta, KOBAYASHI Wataru, IGA Ryuzo, SANJI Hiroaki, KOTOKU Masaki, ISHII Hiroyuki

    Technical report of IEICE. LQE   112 ( 260 ) 97 - 101  2012.10

     View Summary

    In 100GbE, a multi-lane LAN-WDM system, in which four 25-Gbit/s light sources with different waveglengths are used for the transmitter, was employed. For beyond 100G LAN applications, it is almost unavoidable to use multi-lane system. At the same time, increasing the data rate of serial lanes is also a very important for reducing the number of lanes and the whole size of the transmitter. Here, we developed 1.3-um EADFB lasers with the modulation speed of over 25-Gbit/s for beyond 100G parallel LAN applications. The EADFB lasers developed here can be operated at the modulation speed of 50-Gibt/s and we obtained very clear eye openings up to 40-km transmission with semi-cooled operation (45 degree Celcius). Furthermore, we fabricated a monolithically integrated light source by integrating four these EADFB lasers and developed an ultracompact TOSA. By using the TOSA, 40-Gbit/s operation per channel was confirmed.

    CiNii

  • 超高速イーサネット用変調器集積光源 (特集 フォトニックネットワークに貢献する光半導体技術)

    藤澤 剛, 金澤 慈, 高畑 清人

    NTT技術ジャーナル   24 ( 10 ) 53 - 56  2012.10

    CiNii

  • C-3-33 Transmission characteristics of InP-based transversal filter for monolithically integrated large-power transmitter for 100GbE

    Ueda Y., Fujisawa T., Takahata K., Kotoku M., Takahashi H., Ishii H.

    Proceedings of the Society Conference of IEICE   2012 ( 1 ) 150 - 150  2012.08

    CiNii

  • C-4-9 Ultra compact TOSA for next-generation 100GbE transceiver

    Kanazawa S., Nunoya N., Fujisawa T., Ohki A., Takahata K., Sanjoh H., Iga R., Ishii H.

    Proceedings of the Society Conference of IEICE   2012 ( 1 ) 219 - 219  2012.08

    CiNii

  • C-4-10 43-Gbit/s, uncooled EA-DFB laser with rear-grating structure

    Fujisawa T., Takahata K., Kobayashi W., Kanazawa S., Iga R., Ishii H.

    Proceedings of the Society Conference of IEICE   2012 ( 1 ) 220 - 220  2012.08

    CiNii

  • C-4-7 Large-output-power and low-driving-voltage operation of monolithically integrated transmitter for 100GbE

    Fujisawa T., Takahata K., Kanazawa S., Kobayashi W., Tadokoro T., Iga R., Ishii H.

    Proceedings of the IEICE General Conference   2012 ( 1 ) 258 - 258  2012.03

    CiNii

  • A monolithically integrated light source for future-generation 100GbE transceiver

    FUJISAWA Takeshi, KANAZAWA Shigeru, ISHII Hiroyuki, KAWAGUCHI Yoshihiro, NUNOYA Nobuhiro, OHKI Akira, TAKAHATA Kiyoto, IGA Ryuzo, KANO Fumiyoshi, OOHASHI Hiromi

    Technical report of IEICE. LQE   111 ( 267 ) 77 - 80  2011.10

     View Summary

    We have fabricated a small optical trasnmitter module based on monolithically integrated light source, in which four 25G EADFB lasers and their optical MUX are monolithically integrated on one chip, for middle and long-distance 100GbE. For EA modulators, InGaAlAs-based tensile-strained quantum wells are used for large extinction ratio and the supression of hole pile up effect. Also, a shallow-ridge waveguide buried in low-dielectric constant material (BCB) is employed for larger E/O bandwidth. For the MUX region, on the other hand, a deep-ridge wavegudie is used for its strong optical confinement and low radiation loss and a MMI coupler is used for the MUX for its short length and low wavelength sensitivity. Fabricated chip is packaged in specially designed module with the size of 12mmx20mm. By using the module, we demonstrate 10- and 40-km error-free transmission on single mode fiber under 100-Gbit/s operation at 40 degrees Celcius. These results indicate that the module is useful for future-generation transceiver for 100GbE.

    CiNii

  • A monolithically integrated light source for future-generation 100GbE transceiver

    FUJISAWA Takeshi, KANAZAWA Shigeru, ISHII Hiroyuki, KAWAGUCHI Yoshihiro, NUNOYA Nobuhiro, OHKI Akira, TAKAHATA Kiyoto, IGA Ryuzo, KANO Fumiyoshi, OOHASHI Hiromi

    Technical report of IEICE. OPE   111 ( 266 ) 77 - 80  2011.10

     View Summary

    We have fabricated a small optical trasnmitter module based on monolithically integrated light source, in which four 25G EADFB lasers and their optical MUX are monolithically integrated on one chip, for middle and long-distance 100GbE. For EA modulators, InGaAlAs-based tensile-strained quantum wells are used for large extinction ratio and the supression of hole pile up effect. Also, a shallow-ridge waveguide buried in low-dielectric constant material (BCB) is employed for larger E/O bandwidth. For the MUX region, on the other hand, a deep-ridge wavegudie is used for its strong optical confinement and low radiation loss and a MMI coupler is used for the MUX for its short length and low wavelength sensitivity. Fabricated chip is packaged in specially designed module with the size of 12mmx20mm. By using the module, we demonstrate 10- and 40-km error-free transmission on single mode fiber under 100-Gbit/s operation at 40 degrees Celcius. These results indicate that the module is useful for future-generation transceiver for 100GbE.

    CiNii

  • C-4-21 A high output power 100GbE EADFB laser array

    Kanazawa S., Nunoya N., Fujisawa T., Ohki A., Takahata K., Iga R., Ishii H.

    Proceedings of the Society Conference of IEICE   2011 ( 1 ) 236 - 236  2011.08

    CiNii

  • C-4-22 50-Gbit/s electroabsorption modulators integrated with DFB lasers for post 100GbE

    Fujisawa T., Takahata K., Kobayashi W., Tadokoro T., Kanazawa S., Oohashi H.

    Proceedings of the Society Conference of IEICE   2011 ( 1 ) 237 - 237  2011.08

    CiNii

  • C-4-2 A monolithically integrated light source for 100-Gbit/s Ethernet

    Fujisawa T., Kanazawa S., Nunoya N., Ishii H., Kawaguchi Y., Ohki A., Fujiwara N., Takahata K., Iga R., Kano F., Oohashi H.

    Proceedings of the Society Conference of IEICE   2010 ( 1 ) 192 - 192  2010.08

    CiNii

  • C-4-3 A low-voltage operation of 100GbE EADFB laser array module

    Kanazawa S., Fujisawa T., Nunoya N., Ishii H., Kawaguchi Y., Ohki A., Fujiwara N., Takahata K., Iga R., Kano F., Oohashi H.

    Proceedings of the Society Conference of IEICE   2010 ( 1 ) 193 - 193  2010.08

    CiNii

  • High-Speed Optical Packet Processing Technologies for Optical Packet-Switched Networks

    TAKENOUCHI Hirokazu, NAKAHARA Tatsushi, TAKAHATA Kiyoto, TAKAHASHI Ryo, SUZUKI Hiroyuki

    IEICE Trans. Electron., C   88 ( 3 ) 286 - 294  2005.03

     View Summary

    Asynchronous optical packet switching (OPS) is a promising solution to support the continuous growth of transmission capacity demand. It has been, however, quite difficult to implement key functions needed at the node of such networks with all-optical approaches. We have proposed a new optoelectronic system composed of a packet-by-packet optical clock-pulse generator (OCG), an all-optical serial-to-parallel converter (SPC), a photonic parallel-to-serial converter (PSC), and CMOS circuitry. The system makes it possible to carry out various required functions such as buffering (random access memory), optical packet compression/decompression, and optical label swapping for high-speed asynchronous optical packets.

    CiNii

  • B-10-78 Photonic Time-Domain Add-Drop Multiplexer

    Takahata Kiyoto, Takahashi Ryo, Nakahara Tatsushi, Takenouchi Hirokazu, Suzuki Hiroyuki

    Proceedings of the IEICE General Conference   2004 ( 2 ) 449 - 449  2004.03

    CiNii

  • 40-Gbit/s label recognition and self-routing of optical packets using serial-to-parallel conversion

    NAKAHARA Tatsushi, TAKAHASHI Ryo, TAKENOUCHI Hirokazu, YASUI Takako, TAKAHATA Kiyoto, SUZUKI Hiroyuki

    Technical report of IEICE. OPE   103 ( 428 ) 65 - 70  2003.11

     View Summary

    Optical label processing of fast and burst optical packets is the key technology for constructing large-capacity optical packet-switched networks. To realize this, we have developed components that can interface the fast optical labels over 40 Gbit/s with such an intelligent electronic circuit as a CMOS processor. The components are an optical clock-pulse generator (single pulse generator) and an all-optical serial-to-parallel converter. In this paper, we describe the characteristics of these components. We also describe the demonstration of 40-Gbit/s optical label recognition and 1x4 self-routing of optical packets by using these components and a CMOS circuit.

    CiNii

  • Enlargement of Bandwidth of 60-GHz Monolithically Integrated Photonic Millimeter-Wave Emitter

    Takahata Kiyoto, Ito Tsuyoshi, Muramoto Yoshifumi, Ishibashi Tadao, Ito Hiroshi

    Proceedings of the Society Conference of IEICE   2001 ( 1 ) 510 - 510  2001.08

    CiNii

  • PHOTONIC MICRO/MILLIMETER-WAVE SOURCES

    Ishibashi T., Fushimi H., Furuta T., Takahata K., Ohno T., Ito H.

    Proceedings of the IEICE General Conference   2001 ( 2 ) 786 - 787  2001.03

    CiNii

  • 電磁エネルギーの有効利用 電源不要な超小型光マイクロ波変換モジュール

    高畑 清人, 福島 誠治, 三田池 成幸

    EMC   13 ( 8 ) 104 - 111  2000.12

    CiNii

  • 長波長帯超高速モノリシック受信用OEIC

    高畑 清人, 村本 好史, 深野 秀樹

    NTT R & D   49 ( 9 ) 546 - 552  2000.09

    CiNii

  • 40-Gbit/s monolithic receiver OEIC with output voltage of 1 V_<p-p>

    Takahata K., Muramoto Y., Fukano H., Matsuoka Y.

    Proceedings of the IEICE General Conference   2000 ( 1 ) 294 - 294  2000.03

    CiNii

  • Edge-illuminated refracting-facet photodiode with uni-travelling-carrier structure

    Muramoto Y., Fukano H., Takahata K., Matsuoka Y.

    Proceedings of the IEICE General Conference   2000 ( 1 ) 370 - 370  2000.03

    CiNii

  • Optically-fed radio access point module for a 5.8-GHz fiber radio system

    Fukushima S., Fukano H., Yoshino K., Matsuoka Y., Mitachi S., Takahata K.

    Proceedings of the IEICE General Conference   2000 ( 1 ) 690 - 690  2000.03

    CiNii

  • Zero-biased radio access point module for a 5.8-GHz fiber radio system

    Fukushima Seiji, Fukano Hideki, Yoshino Kaoru, Matsuoka Yutaka, Mitachi Seiko, Takahata Kiyoto

      99 ( 662 ) 43 - 48  2000.03

     View Summary

    A bias-free access point module was developed for a fiber radio downlink. The module consists of a uni-traveling-carrier photodiode, an antenna, and a single-mode fiber as an input interface. The maximum output power is 1.4 dBm at a 5.8-GHz carrier frequency without any electric power supply. The module is only 5x2x1 cm.

    CiNii

  • 40-Gbit/s Photoreceiver OEIC Comprising a Multimode WGPD and a Distributed Amplifier

    Takahata K., Muramoto Y., Fukano H., Miyamoto Y., Matsuoka Y.

    Proceedings of the Society Conference of IEICE   1999 ( 1 ) 289 - 290  1999.08

    CiNii

  • 50-Gbit/s Opcration of Monolithic Photoreceiver OEIC Module

    Takahata K., Miyamoto Y., Muramoto Y., Fukano H., Matsuoka Y.

    Proceedings of the IEICE General Conference   1999 ( 1 ) 240 - 240  1999.03

    CiNii

  • 40-Gbit/s Operation of Photoreceiver OEIC Comprising a Waveguide pin-PD and a Distributed Amplifer

    Takahata K., Muramoto Y., Fukano H., Kato K., Kozen A., Nakajima O., Matsuoka Y.

    Proceedings of the IEICE General Conference   1998 ( 1 ) 386 - 386  1998.03

    CiNii

  • 30-Gbit/s Monolithic Photoreceiver Consisting of a Waveguide p-i-n Photodiode and a Distributed Amplifier

    TAKAHATA K., MURAMOTO Y., FUKANO H., KATO K., NOGUCHI K., KOZEN A., NAKAJIMA O., KIMURA S., IMAI Y.

    Technical report of IEICE. LQE   97 ( 153 ) 41 - 46  1997.07

     View Summary

    A photoreceiver OEIC composed of a waveguide p-i-n photodiode and a HEMT baseband distributed amplifier has been constructed. It has a 3-dB-down frequency of 20 GHz and operates at 20Gbit/s with a sensitivity of -10.4 dBm. It also shows good eye opening at 30 Gbit/s. Concerning the potencial of both components, our integration concept has a possibility of achieving ultra-high-speed operation over 40 Gbit/s.

    CiNii

  • 30-Gbit/s Operation of Photoreceiver OEIC Comprising a Waveguide pin-PD and a Distributed Amplifier

    Takahata K., Muramoto Y., Fukano H., Kato K., Kozen A., Noguchi K., Nakajima O., Kimura S., Imai Y.

    Proceedings of the IEICE General Conference   1997 ( 1 ) 346 - 346  1997.03

    CiNii

  • High Gain and Wide Bandwidth Photoreceiver Monolithically Integrated with Differential Amplifier

    Takahata K., Ikeda M., Akatsu Y., Kohzen A., Akahori Y., Nakajima O.

    Proceedings of the IEICE General Conference   1996 ( 1 ) 360 - 360  1996.03

    CiNii

  • A 10Gbit/s Monolithically Integrated Two-Channel Photoreceiver Array using Waveguide p-i-n PDs and HEMTs

    Takahata K., Muramoto Y., Akatsu Y., Agahori Y., Kohzen A., Itaya Y.

    Proceedings of the IEICE General Conference   1995 ( 1 ) 174 - 174  1995.03

    CiNii

  • Optical distribution of ion temperature in WT-3

    ERIGUCHI K., TAKAHATA K., SUEMITSU H., FUJIMOTO T., WT- GROUP

    Meeting Abstracts of the Physical Society of Japan   45   152 - 152  1990

    DOI CiNii

  • 6a-J-10 Radial distribution of impurity ions in a WT-III tokamaku plasma

    Takahata K., Eriguchi K., Suemitsu H., Fujimoto T., WT-III group

    Meeting Abstracts of the Physical Society of Japan   1989   254 - 254  1989

    DOI CiNii

  • 5a-E6-7 軽元素不純物イオンの分布と温度の決定

    高畑 清人, 沢田 圭司, WT-グループ

    秋の分科会予稿集   1988   196 - 196  1988

    DOI CiNii

  • 5a-E6-8 中性水素発光線強度比によるプラズマ診断〜中性水素原子・分子・電子密度

    沢田 圭司, 高畑 清人, WT-グループ

    秋の分科会予稿集   1988   197 - 197  1988

    DOI CiNii

▼display all

Research Projects

  • 自由空間電子走行型光電変換デバイスの創生とテラヘルツ波パルスビームの実現

    Project Year :

    2020.04
    -
    2023.03
     

     View Summary

    研究代表者らが開拓してきた、レーザ光のコヒーレンス性を用いたフォトミキシングによるテラヘルツ波発生・制御技術を新展開させるため、革新的デバイスを実現し、従来困難であった時間的かつ空間的なエネルギーの集中を可能とする「テラヘルツ波パルスビーム」の基盤技術大系を確立する。具体的には、半導体内で光電子を走行させる従来手法から脱却し、自由空間での電子走行により既存技術よりも100倍以上高出力な、新規概念のデバイスを創生する。そして本デバイスだからこそ実現可能となる高出力テラヘルツ波パルスビームを用いた500GHz~1THz級の超高速無線通信やテラヘルツ波深層イメージング等の新産業開拓可能性を探索する

  • Study on an inter-channel crosstalk in a multi-channel optical transmitter module for multi-level pulse amplitude modulation.

    Project Year :

    2017.04
    -
    2020.03
     

  • 光信号処理用全光シリアル-パラレル変換回路の研究

    公益財団法人電気通信普及財団  研究調査助成

    Project Year :

    2019.04
    -
    2020.03
     

  • 多値振幅変調用小型多チャネル光送信モジュールのチャネル間クロストークに関する研究

    独立行政法人日本学術振興会  科研費

    Project Year :

    2017.04
    -
    2020.03
     

     View Summary

    本研究では、次々世代以降の高速光イーサネット、及び高速高密度光インタークネクションに共通して必要となる小型多チャンネル多値振幅変調光電気インターフェイスに適用する光送信モジュールを対象として、高速多値変調信号のチャネル間クロストークの影響に着目して、次の3つの課題に取組んでいる。課題(1)クロストーク抑制に適したモジュール構造の探求。課題(2)チャネル間隔とクロストークの相関の明確化。課題(3)クロストークペナルティの簡易な評価方法を確立。以下、各々の課題について今年度の研究実績を記述する。課題(1):高速光信号を生成する電界吸収型変調器集積DFBレーザ(EML)とその変調器部への変調電気信号を伝達するための高周波伝送線路基板との接続にハンダバンプを用いる構造について、今年度導入した三次元電磁界シミュレータ上に解析モデルを構築した。解析は基礎検討の段階であり、隣接チェネル間クロストークを解析するための2チャネルモデルを用いて、バンプの位置、数を変化させた際の信号伝送特性(伝送損失、クロストーク信号レベル)の変化をチェックした課題(2):光送信モジュールの特性解析のためには電気の入力信号からEMLの光出力までを統合的に解析する光電気統合解析モデルの構築が必要となるが、今年度は基礎検討として電気回路シミュレータ上にEML等価回路モデルを構築し、それを用いてクロストークに起因する伝送信号の劣化度合いを検証した。課題(3)伝送信号の符号誤り率(BER)の劣化度合いを表す指標であるクロストークペナルティを従来の評価方法(BER測定に基づく評価)と比較して短時間で評価する方法を確立するために、クロストークの影響を雑音として捉えて信号雑音比(SNR)とクロストークペナルティの相関に着目する評価手法の基礎検討を行った。今年度は研究室内のシミュレーション環境の立上げ、及び解析モデルの検討に計画よりも時間を費やしたため、研究の進捗が若干遅れた。課題(1)については、ハンダバンプを用いた構造についての解析モデルを構築したが、条件の最適化や新たな構造の検討は完了することが出来ていない。課題(2)については、光送信モジュール内での電気クロストークの発生箇所として隣接伝送線路間を想定した解析モデルを構築し、その伝送信号への影響を検証した。しかし、隣接EML間のクロストークについては着手出来ていない。課題(3)については、クロストークペナルティの新たな評価手法について試行錯誤した結果、クロストークの影響を雑音として捉えて信号雑音比の変化に着目する手法を有力と判断した。課題(1)クロストーク抑制に適したモジュール構造の探求、については、特にLSIチップ間光インタークネクションでは高密度化の要求が高いことから、チャネル間隔を100μm以下まで狭小化してもクロストークを抑圧できるモジュール構造の探索を行う。隣接する信号線の間の強化グランドを配線基板面だけでなくその周囲の空間部分に対しても設ける構造の導入、電磁波遮断物質の利用等、広い範囲で構造、技術探索を実施し、PAM4信号に対してクロストークを十分に抑圧できる構造を提案する。課題(2):チャネル間隔とクロストークの相関の明確化、については、隣接伝送線路間だけではなく隣接EML間のクロストークも取り入れた光電気統合解析モデルを構築し、シミュレーションによりチャネル間隔とクロストークの相関を明確化する。課題(1)で検討されたクロストーク抑圧モデルを逐次取り入れることで統合モデルをアップデートし、新たな構造に対してもチャネル間隔とクロストークの相関を明確化する。課題(3)クロストークペナルティの簡易な評価方法を確立、については、SNRに基づいたクロストークペナルティ評価手法をNRZ信号に対して確立した後に、これをPAM4信号にも拡張するために必要な改良を加え、PAM4信号に対しても従来手法よりも簡易に、且つ短時間でクロストークペナルティを導出する手法を確立する

Presentations

  • Design of a photonic integrated circuit for product-sum computing

    Ruikang Luo, Kiyoto Takahata

    The 15th International collaboration Symposium on Information, Production and Systems (ISIPS 2021), B2-6 

    Presentation date: 2021.11

  • Dispersion engineering of kagome lattice Si photonic crystal waveguide

    Deji Li, Kiyoto Takahata

    The 15th International collaboration Symposium on Information, Production and Systems (ISIPS 2021), B2-3 

    Presentation date: 2021.11

  • Siプラットフォーム上O帯メンブレンInGaAlAs電界吸収型変調器

    開達郎, 相原卓磨, 前田圭穂, 藤井拓郎, 佐藤具就, 硴塚孝明, 髙畑清人, 松尾慎治

    第82回応用物理学会秋季学術講演会, 10p-N405-9 

    Presentation date: 2021.09

  • Siプラットフォーム上薄膜InGaAsP電界吸収型変調器

    開達郎, 相原卓磨, 前田圭穂, 藤井拓郎, 土澤泰, 髙畑清人, 硴塚孝明, 松尾慎治  [Invited]

    信学技報, OCS2020-41 OPE2020-73 LQE2020-79 

    Presentation date: 2021.02

  • Design of a Compact Silicon Electro-Optic Modulator Based-on Indium-Tin-Oxide Integrated Directional Coupler with Subwavelength Gratings

    Hanzhi CHEN, Kaihang LU, Takaaki KAKITSUKA, Kiyoto TAKAHATA

    The 14th International collaboration Symposium on Information, Production and Systems (ISIPS 2020), B3-5 

    Presentation date: 2020.11

  • Design of Mode Size Converter on SOI Waveguide for Improvement of Coupling Efficiency and Misalignment Tolerance with Single-mode Fiber

    Liang DONG, Deji LI, Kiyoto TAKAHATA

    The 14th International collaboration Symposium on Information, Production and Systems (ISIPS 2020), B3-2 

    Presentation date: 2020.11

  • New evaluation method of crosstalk penalty for multi-channel transmitters

    Siyuan DUAN, Hanzhi CHEN, Kiyoto TAKAHATA

    The 13th International collaboration Symposium on Information, Production and Systems (ISIPS 2019), B8-7 

    Presentation date: 2019.11

  • Bidirectional optical delay unit for 8-bit sereial-to-parallel conversion

    Chenge AO, Ruikang LUO, Kiyoto TAKAHATA

    The 13th International collaboration Symposium on Information, Production and Systems (ISIPS 2019), B8-2 

    Presentation date: 2019.11

  • A compact SOI-based polarization beam splitter

    Jingyan Chang, Ye Bo, Kiyoto Takahata

    Presentation date: 2019.09

  • Mode size converter on SOI waveguide for improvement of coupling with SMF

    Liang DONG, Hao LI, Kiyoto TAKAHATA

    Presentation date: 2019.09

  • Training Dataset Synthesis for Planar Filter Circuits Learning

    Kosuke Katayama, Kiyoto Takahata, Takashi Ohsawa, Takaaki Baba

    Presentation date: 2018.09

  • Design of multi-layer optical waveguide with a tapered cube core structure

    Chonglun Cui, Songpin Ran, Takashi Ohsawa, Takaaki Baba, Kiyoto Takahata

    Presentation date: 2018.09

  • Evaluation method of crosstalk penalty based on SNR analysis

    Qiang Du, Liang Dong, Kiyoto Takahata

    Presentation date: 2018.09

  • Analysis on crosstalk of a multi-channel optical transmitter

    Xiangyu Gan, Chang Guo, Jingyan Chang, Kosuke Katayama, Takaaki Baba, Kiyoto Takahata

    Presentation date: 2018.09

  • IEEE802.3における400GbE標準化の状況

    髙畑 清人  [Invited]

    フォトニックデバイス・応用技術研究会  光産業技術振興協会

    Presentation date: 2014.10

  • ECOC2009 国際会議報告

    髙畑 清人  [Invited]

    エイトラムダフォーラム  イーラムダネット

    Presentation date: 2009.10

▼display all

Specific Research

  • 大容量光インターコネクション用多層光導波路構造の研究

    2021  

     View Summary

    For chip-to-chip inter-connection, a Tbit/s-classcapacity is expected in the near future. Therefore, optical chip-to-chipinterconnection has attracted considerable attention owing to its high-speedand power-saving operation. To achieve a huge capacity, a multilayer opticalwaveguide structure for connection between chips is indispensable, and such astructure requires vertical waveguide section which is much difficult to formthan a conventional horizontal waveguide. For easy fabrication of the verticalwaveguide section, a design of multilayer waveguide structure with nonuniform cuboidcores has been studied in our lab. However, an unnatural layer-numberdependence of coupling efficiency has been observed.&nbsp;&nbsp;Inthis year, we have found the reason of such an unnatural characteristics of couplingefficiency by detailed analysis on the light beam distribution and optimizedthe design of nonuniform cuboid cores. The optimized design can provide aten-layer waveguide with a coupling efficiency larger than -4 dB. In addition,the crosstalk dependence on the channel pitch between two waveguides have beeninvestigated. The results indicate that the nonuniform cuboid core structure canaccept the 28% narrower channel pitch than the uniform cube core structure whenthe crosstalk criterion is -20 dB.

  • 多値振幅変調用小型多チャネル光送信モジュールのチャネル間クロストークに関する研究

    2020  

     View Summary

    In this work, we have continued "Studyon an inter-channel crosstalk in a multi-channel optical transmitter module formulti-level pulse amplitude modulation”, which was funded by JSPS KAKENHI untilMarch 2020. In KAKENHI work, the new method which can halve a measurement timeof a crosstalk penalty by replacing some of bit-error-rate measurements with measurementof noise power was proposed and verified by optical transmission simulationusing a transmission system model equipped with ideal models ofelectro-absorption optical modulator and photodiode. In this work, accuratemodels closer to real optical devices have been used in the transmission systemmodel instead of the ideal device models. With this upgraded model, theproposed evaluation method has been verified, and its effectiveness had beenconfirmed. In addition, we have also examined a method for evaluating thecrosstalk penalty based on the degree of signal waveform deterioration due tothe influence of crosstalk.

  • 導波路型光デバイスを用いた光論理演算方法の研究

    2020  

     View Summary

    &nbsp;For future all-optical signal processing, a 3×3 multi-mode interferometer(MMI) based optical logic gate is studied by to achieve logic OR, XOR, NAND, XNOR, AND, NOR, and NOT (= seven logics) with a fixed design of the MMI. Due to the operating principle of the MMI, the logic NOR and logic AND are difficult to be achieved only by phase shift keying (PSK) signal or on-off keying (OOK) signal with MMI based optical logic gates. Therefore, a combination between two input signals and reference signal has been investigated in detail by using numerical simulation based on beam propagation method (BPM). The logic operation of the MMI is evaluated using a contrast ratio of output signal “1” to output signal “0”. It has been shown that all seven logic operations are achievable with an identical 3×3 MMI based optical logic gate by adjusting combination between input signals.&nbsp;

  • 光信号処理用小型光パラレル・シリアル変換回路構成法の研究

    2019  

     View Summary

    A simple and compact design of a delay waveguide unit for an optical serial-to-parallel conversion (OSPC) is proposed. It consists of a delay waveguide and Bragg reflectors and can supply optical path difference with one channel configuration for bit separation and unification in the time domain. In the unit, an identical delay waveguide can be used for several different carrier waves and the one delay unit is used twice in bidirectional operation. This leads to reduction in device complexity and size. The proposed unit is designed based on the silicon-on-insulator optical waveguide with eight apodized gratings for 40-Gbit/s 1:8 OSPC. The designed unit shows the potential to reduce the size of the delay part in the OSPC to about 1/8 of the reported approach, and good wavelength selectivity of eight gratings is confirmed with simulation.

  • 高速大容量光インターコネクション用高密度多チャンネル光導波路構成法の研究

    2017  

     View Summary

    将来の超高性能AI等で必須となる高速大容量LSIチップ間通信への適用を目的として、並列光インタークネクション用高密度多チャンネルポリマー光導波路について、以下2項目の基礎検討を行った。1) 高密度化のための多チャネル導波路レイアウトの最適化1.55 mm帯シングルモード導波路に対して面心正方格子状導波路レイアウトを用いた場合に、チップサイズの1/4のエリアに10,000ch以上の光導波路を配置可能であること確認した。2)垂直方向の低損失光導波構造の検討多層光導波路を用いたチップ間接続でキーとなる垂直方向の光導波構造について、クラッド層にも付加的に導波路構造を導入することで大幅な損失改善が見込めることを示した。

 

Syllabus

▼display all