基于光学-微波同步的低噪声微波产生方法

低噪声微波在冷原子光钟、光子雷达、大科学装置远程同步等领域具有重要的应用价值.本文介绍了一种基于光学-微波相位探测技术的低噪声微波产生方案,利用光纤环路光学-微波鉴相器,将超稳激光的频率稳定度相干传递至介质振荡器.实验采用梳齿相位参考至超稳激光的窄线宽掺铒光纤飞秒光学频率梳,结合光纤环路光学-微波鉴相器和精密锁相装置,将7 GHz介质振荡器同步至光频梳重复频率的高次谐波,同步后的光脉冲序列与微波信号的剩余相位噪声为–100 d Bc/Hz@1 Hz,定时抖动为8.6 fs 1 Hz—1.5 MHz];通过搭建两套低噪声微波产生系统,测得7 GHz微波的剩余相位噪声为–90 d Bc/Hz@1 Hz,对应的频率稳定度为4.8×10^–15@1 s.该研究结果对基于光学相干分频的低噪声微波产生提供了一种新思路.

Low-noise microwave generation based on optical-microwave synchronization

Low-noise microwave signals are of vital importance in fields such as cold atomic optical clocks,photon radars,and remote synchronization at large facilities.Here,we report a compact all-optical-fiber method to generate a low noise microwave signal,in which the fiber loop optical-microwave phase detector is used to coherently transfer the frequency stability of the ultra-stable laser to the microwave.Combining a narrow linewidth optical frequency comb and a fiber loop optical-microwave phase discriminator,a tight phase-lock between 7 GHz dielectric oscillator and optical frequency comb is achieved,the remaining phase noise of the synchronized optical pulse sequence and the microwave signal is–100 dBc/Hz@1 Hz,and the timing jitter is 8.6 fs(1 Hz—1.5 MHz);by building two sets of low-noise microwave generation systems,the measured residual phase noise of the 7 GHz microwave is–90 dBc/Hz@1 Hz,and the corresponding frequency stability is 4.8×10^–15@1 s.These results provide a novel idea for generating the low-noise microwaves based on optical coherent frequency division.