用于 BOTDR 的双通道可调 M-Z 干涉仪研究

摘要

In order to separate and extract the Brillouin scattering signal from backscattering light in BOTDR distribu-ted optical fiber sensing technology,a high extinction ratio dual-pass tunable Mach-Zehnder interferometer was de-signed.The interferometer consists of two 3dB coupler,electric fiber delay line,polarization controller and optical iso-lator.The performance of the M-Z interferometer was tested by using a C band broadband light source (ASE).Pulse light which pulse wide is 1 00 ns,repetition frequency is 20 kHz was injected into a single mode fiber with the length of 5 km.The backscattering light that generated from the fiber was filtered through the M-Z interferometer,then the output spectrum signal was detected by the spectrometer.Experimental results show that the M-Z interferometer can a-chieve a large range of high precision adjustable filtering function,and Rayleigh scattering light was suppressed greater than 20 dB.It can effectively separate and extract the Brillouin scattering light signals from the backscattering light.%针对 BOTDR 分布式光纤传感技术中背向散射光中布里渊散射信号光的分离提取问题，设计了一种高消光比双通道可调 M-Z 干涉仪，该干涉仪由两个3 dB 耦合器、电动光纤延迟线、偏振控制器及光隔离器构成。使用 C 波段宽带光源（ASE）对 M-Z 干涉仪性能进行了检测。并将脉宽为100 ns，重复频率为20 kHz 的脉冲光入射到长度为5 km 的普通单模光纤中，将其产生的背向散射光经过 M-Z 干涉仪滤波后，通过光谱仪检测其输出的光谱信号。实验结果表明该干涉仪能够实现大范围高精度可调节滤波功能，对瑞利散射光的抑制超过20 dB，可以有效地将背向散射光中的布里渊散射光信号分离提取出来。