偏振态退化对双马赫-曾德尔分布式光纤传感系统定位性能的影响分析

Analysis on the influence of polarization state degradation to the performance of Mach-Zehnder distributed optical-fiber sensing system

基于线偏光进入长程传感光路后退偏为椭圆偏振光的基本事实,利用椭圆偏振光干涉法得出了退偏情况下干涉信号的一般公式。通过实际干涉信号与理想干涉信号的对比分析,发现由于退偏作用的存在,输出信号可见度减小为V0(V0=(α21+b21)^(1/2)≤1);辅以琼斯矩阵法,鉴于顺、逆时针光路退偏作用的非对称性,探测器D1、D2探测到的干涉信号相位误差ζ1≠ζ2,从而将误差引入信号时延Δτ,严重影响传感系统定位精度。进一步揭示出对系统进行偏振态衰落抑制方法研究的重要意义。

Based on the facts that polarization degeneration will happen when the linear polarized light transmits into long - distance sensing fibers , use ellipti- cally polarized light interferometry to ohatain the general formula of interference signals. Through comparing practical interference signal to the ideal one, during to the existence of depolarization effect, find that the output signal visibility reduced to V0（V0=√a1^2＋b1^2≤1）; supplemented by Jones matrix method, in view of the non - symmetry characteristics of polarization degeneration in clockwise and anti - clockwise optical - fiber path, the phase errors of interference signals are not equal, which will introduce error to signal delay Ar, and then seriously affect sensing system positioning accuracy. Further reveal the importance of taking research on the method, of inhibiting the polarization state decline.