基于偏振态变化时延估计的分布式光纤传感系统

Distributed optical fiber sensing system based on SOP time delay estimation

提出一种基于偏振态(SOP)变化时延差估计的分布式光纤传感系统。本系统采用两个直流光信号在传感光纤中双向注入,振动会对正向和逆向光造成SOP变化,在各自的尾端利用起偏器检测SOP变化并转换为光强信息。两路信号间的时延差表明了振动的位置信息。对时延差形成的原因进行了理论分析,并阐明利用互相关算法计算该时延差并进行分布式传感、定位的原理。实验证明了该定位原理的正确性,将所得两路电信号利用快速傅里叶变换(FFT)互相关算法,对偏振扰动点进行定位,取得到较好的结果,实验结果表明系统定位精度可达0.8%,定位误差小于300m。

This paper presents a distributed optical fiber sensing system based on the state of polarization（SOP） changes delay estimation.Two optical signals are fed into the sensing fiber bi-directionally.The vibration will result in the polarization of light changes both forward and backward.At the end of each side,a polarizer is employed to convert polarization changes to light intensity information.The time delay between two signals indicates the location of the vibration.The analysis of the reason for the formation of two signals′ delay is performed,the correlation algorithm is used to calculate the time delay and the distributed sensing positioning principles are clarified.Experiments are done to show the positioning accuracy of the principle,where good results are obtained from cross-correlation algorithm using FFT of the two-way electric signals,and are used to locate the position of the vibration.Results show that the positioning precision is up to 0.8%,and the maximum error is within 300 m.