Liu Pengcheng, Zheng Pengfei, Yang Huimin, Lin Dongdong, Hu Guohua, Yun Binfeng, Cui Yiping
Appl Opt. 2021 Mar 1;60(7):1930-1936. doi: 10.1364/AO.417003.
The optoelectronic oscillator (OEO) generates low-phase noise and high-frequency microwave signals thanks to a high Q-factor cavity with long and low-loss fiber delay. Traditionally, for the desired mode selection from the ultradense cavity modes, a narrowband electrical filter is needed, whose frequency tuning is very limited. On the other hand, for a tunable OEO offered by a microwave photonic filter (MPF), a paradox existed between the large number of cavity modes and the wide MPF bandwidth. Here, we achieve a tunable OEO using the mode-selection mechanism of parity-time symmetry, which overcomes the paradox. A high Q-factor silicon nitride microdisk resonator ( MDR) is introduced to achieve frequency filtering and tuning. Moreover, the experimental results reveal that the tunable OEO generates a signal range from 3 GHz to 20 GHz with a phase noise about -120/ at a 10 kHz offset frequency.
光电子振荡器（OEO）借助具有长且低损耗光纤延迟的高Q因子腔来产生低相位噪声和高频微波信号。传统上，为了从超密集腔模中选择所需模式，需要一个窄带电滤波器，但其频率调谐非常有限。另一方面，对于由微波光子滤波器（MPF）提供的可调谐OEO，在大量腔模和宽MPF带宽之间存在一个矛盾。在此，我们利用宇称时间对称的模式选择机制实现了一个可调谐OEO，它克服了这一矛盾。引入了一个高Q因子的氮化硅微盘谐振器（MDR）来实现频率滤波和调谐。此外，实验结果表明，可调谐OEO在10 kHz偏移频率下产生的信号范围为3 GHz至20 GHz，相位噪声约为-120dBc/Hz。
