A precisely tunable heterodyne-injection-locked dual-loop optoelectronic oscillator (HIL-DL OEO) is analyzed and experimentally demonstrated. The primary loop, utilizing a narrow bandpass filter, generates a frequency-fixed signal, and the secondary loop, incorporating a yttrium iron garnet filter, outputs the tunable signal. The oscillating signal in each loop experiences frequency translation at an external frequency translation module (FTM) and is then fed to the other loop. The frequency translation at the FTM, which is composed of two mixers and a power splitter, is realized with the help of a tunable low-frequency signal. Thanks to the low-frequency signal, the oscillation frequency in the secondary loop would vary accordingly under injection locking.

中文翻译：

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精确可调外差注入锁定双环光电振荡器

分析和实验证明了一种精确可调的外差注入锁定双环光电振荡器（HIL-DL OEO）。利用窄带通滤波器的初级环路产生一个固定频率的信号，而结合钇铁石榴石滤波器的次级环路则输出可调信号。每个回路中的振荡信号在外部频率转换模块（FTM）处经历频率转换，然后馈送到另一个回路。FTM的频率转换由两个混频器和一个功率分配器组成，它是通过可调的低频信号来实现的。由于低频信号，在注入锁定下，次级回路中的振荡频率将相应地发生变化。