Zhou Wen, Yu Benli, Zhang Jihao, Shi Jinhui, Guang Dong, Zuo Cheng, Mu Shengquan, Fang Chongxu, Zhang Daoxin, Lin Jiping, Wu Xuqiang
Opt Express. 2023 Oct 9;31(21):33765-33775. doi: 10.1364/OE.493033.
The reference interferometer scheme is an effective noise reduction method, but the optical path length difference (OPD) of the two interferometers must be strictly equal, which limits its application in practical environments. In this paper, an improved reference interferometer demodulation technique without strictly equal OPDs is proposed to suppress phase noise. By introducing a reference interferometer, the phase noise can be removed from the demodulation results. The combination of the differential self-multiplication algorithm and the fitted phase modulation depth calculation formula can evaluate the phase modulation depth of both interferometers in real time and simultaneously eliminate the nonlinear distortion caused by phase modulation depth drift and the effect of different OPDs on the reference interferometer scheme. The experimental results show that the technique can obtain highly stable and accurate demodulation results even if the OPDs of the two reference interferometers are different. The phase modulation depth calculation error is less than 0.57%, the maximum phase noise reduction is 15 dB, the average reduction is 9 dB, the minimum total harmonic distortion is 0.17%, and the SINAD reaches 35.90 dB.
参考干涉仪方案是一种有效的降噪方法，但两个干涉仪的光程差（OPD）必须严格相等，这限制了其在实际环境中的应用。本文提出了一种改进的参考干涉仪解调技术，该技术无需严格相等的光程差即可抑制相位噪声。通过引入参考干涉仪，可以从解调结果中去除相位噪声。差分自乘法算法与拟合相位调制深度计算公式相结合，能够实时评估两个干涉仪的相位调制深度，并同时消除由相位调制深度漂移引起的非线性失真以及不同光程差对参考干涉仪方案的影响。实验结果表明，即使两个参考干涉仪的光程差不同，该技术也能获得高度稳定且准确的解调结果。相位调制深度计算误差小于0.57%，最大相位噪声降低15 dB，平均降低9 dB，最小总谐波失真为0.17%，信纳比达到35.90 dB。
