Precisely Tunable Heterodyne-Injection-Locked Dual-Loop Optoelectronic Oscillator

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. (C) 2021 Society of Photo-Optical Instrumentation Engineers (SPIE)