激光强度起伏及相位噪声对光学双频探测的影响

针对利用光纤延时自差系统获得双频拍频光的方法, 建立了激光源强度起伏和相位噪声对拍频光功率谱影响的理论模型, 并基于该模型进行了数值分析和模拟。结果表明, 短延时差比长延时差更有利于减小激光器的噪声干扰。当延时差小于激光相干时间时, 激光线宽越大, 强度起伏越大, 信号的信噪比越低。当延时差远大于激光相干时间时, 激光器的相位噪声成为拍频光信号展宽的主要来源, 且相位噪声越大, 拍频光信号功率越小; 强度起伏也有一定的展宽效应, 但对于拍频信号功率有增大作用。在长延时情况下, 拍频光信号功率和线宽随两个频率光的延时差呈余弦规律变化, 存在最佳工作点。

Abstract

Aiming at the dual-beat-frequency light which is obtained by using fiber delayed self-heterodyne system, the theoretical model for power-spectrum of beat-frequency signal influenced by intensity fluctuation and phase noise of laser source is built. Based on the model, the numerical analyses and simulations are carried out. The results show that the short delay time between the two paths of laser can better decrease the influence of laser noise than the long delay time. When the delay time is shorter than the coherence time of the laser, the signal to noise ratio (SNR) of the beat-frequency signal can decrease as the laser linewidth and the intensity fluctuation increase. When the delay time is much longer than the coherence time of the laser, the laser phase noise becomes the main reason for spectral broadening of the beat-frequency signal. In addition, the power of the beat-frequency signal can decrease as the phase noise increases. The intensity fluctuations also make contribution to the broadening of the beat-frequency signal while increasing the power of the beat-frequency signal. When the delay time is long, the linewidth and power of the beat-frequency signal will change in accordance with the law of cosine as the delay time changes, and there are optimum operating points.

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单慧洁, 杨宏志, 杨苏辉, 赵长明, 张海洋. 激光强度起伏及相位噪声对光学双频探测的影响[J]. 光学学报, 2016, 36(12): 1212005. Shan Huijie, Yang Hongzhi, Yang Suhui, Zhao Changming, Zhang Haiyang. Effects of Laser Intensity Fluctuation and Phase Noise on Dual-Frequency Laser Detection[J]. Acta Optica Sinica, 2016, 36(12): 1212005.

激光强度起伏及相位噪声对光学双频探测的影响

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