An approach for frequency division of an optical pulse train (OPT) based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator (MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed.

提出了一种基于耦合式光电振荡器的动态腔长长时稳定控制方案，当光谐振腔腔长变化时，通过同相正交（in-phase/quadrature，I/Q）混频器测量光谐振腔内选定两点的谐振相位变化量，反馈控制光电再生腔的光延迟线进行再生腔长跟随补偿，实现可变腔长的耦合式光电振荡器的锁模控制输出，从而将变化的谐振腔腔长转化为变化的谐振频率进行精密测量。经过系统实验，当谐振腔长变化时，振荡器可实时锁定输出可变的微波信号，并保持边模抑制比优于47.26 dB，1 h内功率抖动小于0.28 dB，锁定相位误差抖动在±1.5°以内。

提出了一种基于电吸收调制激光器的双功能系统，可以同时实现微波信号的产生和其相位噪声的测量。该系统由基于电吸收调制激光器的光电振荡器模块和基于光延时线技术的相位噪声测量模块构成。通过使用单个电吸收调制激光器代替激光源和强度调制器，所提出的双功能系统不仅成本低廉、结构简单，而且性能表现优异；有利于在基于OEO的射频系统，特别是信号产生系统的研制、优化与工作过程中，及时评估信号源的质量并作出相应的参数调整以优化其性能，为光电振荡器的相位噪声测试提供了简单的解决方案。实验结果表明，由光电振荡器生成的9.952 GHz信号的边模抑制比为66 dB，相位噪声为-116.53 dBc/Hz@10 kHz。此外，相位噪声测量系统的相位噪声基底达-133.71 dBc/Hz@10 kHz，其测量灵敏度优于商用信号分析仪R&S FSV40。

Parity‐time (PT) symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator (OEO) loop. However, most OEO implementations depend on discrete devices, which impedes proliferation due to size, weight, power consumption, and cost. In this work, we propose and experimentally demonstrate an on-chip tunable PT‐symmetric OEO. A tunable microwave photonic filter, a PT‐symmetric mode‐selective architecture, and two photodetectors are integrated on a silicon‐on‐insulator chip. By exploiting an on‐chip Mach–Zehnder interferometer to match the gain and loss of two mutually coupled optoelectronic loops, single‐mode oscillation can be obtained. In the experiment, the oscillation frequency of the on-chip tunable PT‐symmetric OEO can be tuned from 0 to 20 GHz. To emulate the integrated case, the OEO loop length is minimized, and no extra-long fiber is used in the experiment. When the oscillation frequency is 13.67 GHz, the single‐sideband phase noise at 10-kHz offset frequency is -80.96 dBc / Hz and the side mode suppression ratio is 46 dB. The proposed on-chip tunable PT‐symmetric OEO significantly reduces the footprint of the system and enhances mode selection.