Zhao Rui, Yuan Hongyu, Jin Baoquan, Xu Yuelin, Chen Yu, Liu Xin, Bai Qing, Wang Yu
Appl Opt. 2021 Jan 10;60(2):459-464. doi: 10.1364/AO.410938.
A difference-fitting method is proposed to mitigate the low frequency drift of a phase-sensitive optical time domain reflectometry (-OTDR) system caused by laser phase noise. The effective difference region for phase demodulation is theoretically analyzed and experimentally verified, which should be greater than the convolution of the spatial resolution and the length of disturbed optical fiber. Then, a median-fitting algorithm is used to obtain the phase noise of the differential region. The vibration signal of 0.2 Hz is first demodulated with the SNR of 41.79 dB on the optical fiber of 11 km. The low-frequency vibration signals of 0.05 Hz and 0.02 Hz are then successfully restored by using the difference-fitting method, which can effectively eliminate the influence of low frequency drift.
提出了一种差分拟合方法来减轻由激光相位噪声引起的相敏光时域反射仪（-OTDR）系统的低频漂移。从理论上分析并通过实验验证了相位解调的有效差分区域，该区域应大于空间分辨率与受干扰光纤长度的卷积。然后，使用中值拟合算法来获取差分区域的相位噪声。在11 km长的光纤上，首先解调了信噪比为41.79 dB的0.2 Hz振动信号。然后，通过使用差分拟合方法成功恢复了0.05 Hz和0.02 Hz的低频振动信号，该方法可以有效消除低频漂移的影响。
