In the last year, thetunable extinction ratio of dual-parallel Mach-Zehnder (DPMZM) modulator hasbeen experimentally demonstrated. The working parameter of DPMZM can bemeasured by the characterization method. Precise bias control can be applied onMZMs to compensate the power imbalance of sub MZMs. Under this bias state, theextinction ratio can be enhanced and a typical two-tone signal. The outcome ofthis research is summarized in a preparing manuscript and will be submitted toIEEE Access.Based on theproposed method, the application related to opto-electronic oscillator (OEO) canbe investigated. The target of this research is to enhance the extinction ratio(ER) of the optical modulator used inside the OEO and investigate theperformance improvement of the entire OEO. By improving the performance of theOEO, we aim to reduce the gain of the electric amplifier used inside the OEO,and eventually realize a low-cost OEO without the electric amplifier.The theoretical backgroundof OEO has also been reviewed. The most famous theory of OEO is the Yao andMaleki model. According to Yao and Melaki model, in order to reduce the gain ofthe electrical amplifier while maintaining the overall voltage gain, it isnecessary to increase the optical amplification of the EDFA and improve theextinction ratio of the modulator. A serious of experiments has been establishedto verify this issue. The next step is to realize the close loop of OEO withoutelectrical amplifier consider the suppression of phase noise. This work is support by the funding from Grant-in-aidfor transformative research areas A“Photonic Computing” (JSPS KAKENHI Grant Number JP22H05196).Anotherapplication based on precise measurement of DPMZM is real-time RF phase measurementusing single sideband modulation of Mach-Zehnder modulators.  In this method, the phase measurementresults can be derived from the ratio of the 1st order and -1st ordersidebands, meaning the measurement of two data points. Moreover, themeasurement method was experimentally demonstrated, and the calculation was conductedusing a field-programmable gate array (FPGA) in the electrical signal domain. Thistype of measurement technique will be useful for key technologies, such asbeamforming, thereby supporting the future beyond 5G networks. The outcome of thisresearch has been accepted as oral presentation by the 29th Opto-Electronicsand Communications Conference 2024 (OECC2024).