基于微波锁模的超低噪声微波频率梳的产生

Generation of Ultra-Low Noise Microwave Frequency Comb Based on Microwave Mode-Locking Technology

提出了一种利用微波主动锁模的光电振荡器产生微波频率梳的方案,该方案采用传统的光电振荡器(OEO)作为振荡器,利用混频器从外部加入微波调制信号,形成对光电振荡器振荡模式的模式锁定,从而实现微波主动锁模,此时振荡器就产生了一系列频率间隔相等的频率梳。在腔长为1 km时,实验得到了频率间隔为201.2 kHz的微波频率梳信号,其一阶边带相位噪声小于-97.2 dBc/Hz@1 kHz和-116.721 dBc/Hz@10 kHz,单个频率的线宽约为10 Hz。与传统的微波频率梳产生方式相比,该方案的相位噪声指标有很大提高,并且通过改变OEO腔长以及调制信号频率,实现了高次谐波锁模,得到了从100 kHz到6 MHz的不同信号间隔的微波频率梳信号。

This paper proposes a microwave mode-locking frequency comb scheme using active mode-locking technology and photoelectric oscillator.The scheme uses traditional optoelectronic oscillators(OEO)as oscillators,and uses a mixer to add microwave modulation signals from outside to form an optoelectronic oscillator.The mode-locking of the oscillator oscillation mode realizes the microwave active mode-locking.At this time,the oscillator generates a series of frequency combs with equal frequency intervals.When the system loop cavity is 1 km long,low-phase-noise microwave comb signals with a frequency interval of 201.2 kHz are obtained through experimental analysis.The firstorder carrier phase noise of the microwave comb signal is-97.2 dBc/Hz@1 kHz and-116.721 dBc/Hz@10 kHz,and the line width is approximately 10 Hz.The scheme is considerably improved in the phase-noise index compared to the conventional microwave frequency comb generation method.Furthermore,microwave frequency combs signals with a tunable frequency interval ranging from 100 kHz to 6 MHz can be obtained by changing the cavity length and modulation signal frequency of OEO.