干涉型光纤安防系统偏振误差机理分析

对应用于安全防范、石油管道监测的双马赫-曾德型光纤安防系统的结构及工作原理进行分析.针对现场测试结果,分析了影响系统精度的误差因素,提出影响系统精度和增加误报率主要是由于偏振态变化不一致导致的两路干涉信号幅值波动以及附加相位噪声引入的距离定位误差.并展开对系统偏振衰落形成机理及其主要影响因素的定量定性分析,同时建立数学模型,进行仿真计算.最后通过对双马赫-曾德型光纤安防系统样机进行实验,验证了分析结果的正确性.

Analysis of polarization dependence of fiber optic security systems

The fiber-optic distributed disturbance sensor with dual Mach-Zehnder interferometers can be used in detecting intruder, cracks, and oil or fuel leaks. The position of the disturbance was obtained by the time delay difference between the output signals of the two Mach-Zehnder interferometers. According to the theory analysis, the records of the experiments in the major cases are compared. The polarization-induced fading phenomenon will lead to the inaccuracy of the position of the disturbance. The factors affected the system error are discussed. In order to find the relationship between the change of the environment conditions and the output states of polarization, the experiments were made. The experimental data and the simulation result on the Poincare sphere are similar.