High-Resolution Brillouin Optoelectronic Oscillator Using High-Order Sideband Injection-Locking

Microwave signals with high frequency, flexible tunability, and low phase noise are highly desired in signal processing and radar systems. In this letter, an optical injection-locking scheme using the high-order phase modulation sideband is introduced to realize a stable Brillouin optoelectronic oscillator (OEO). Pure microwave signals up to 40 GHz with low phase noise are obtained using an electrical drive signal below 5 GHz. A flexible frequency tuning with high resolution of 8 MHz is maintained by controlling the electrical drive signal and the slave laser, and the side mode suppression ratio is higher than 60 dB. The phase noise of the OEO-generated microwave signals under different master lasers is measured and compared to verify the significance of the master lasers with ultralow frequency noise. The maximum frequency drift of a 10.79-GHz signal is 1.4 kHz within 600 s, showing the stability of the proposed Brillouin OEO.