基于环结构的新型分布式光纤振动传感系统

提出并验证了一种新颖的基于环形马赫-泽德干涉仪结构的全分布式光纤振动传感系统.采用直流光实时动态定位技术，通过在干涉仪光路中引入环结构，将直线型干涉仪转化为环型回路，使得一个马赫-泽德干涉仪中相向传输两路光波，相当于构成双马赫-泽德干涉仪.当振动信号作用于传感光纤时，相向传输的两路直流光同时产生相同的相位信号并沿不同的路径传输至光接收单元，采用数字信号处理技术分析接收信号即可实时获得振动的空间位置和频率、幅度等特性参数.实验中成功实现了监测距离为1.01km的分布式振动传感，单点振动的空间分辨率小于40m.另外，从理论上分析并模拟了系统对多点同时振动进行检测和定位的可行性.

A novel ring structure-based distributed optical fiber vibration sensing system

A novel distributed optical fiber vibration sensing system is proposed and demonstrated, using a ring structure-based Mach-Zehnder interferometer (MZI). The direct current light-based real-time and dynamic locating technique is exploited. By introducing the ring structure into the interferometer, the linear interferometer is changed into ring type, resulting in two counter-propagating light waves, thus one MZI equally operates as two. When a vibration acts on the sensing fiber, the counter-propagating signals produce identical phase-changes simultaneously, which propagate along different paths to optical receivers. With the help of digital processing technologies to analyze the received signals, the characteristic parameters of vibration, including the spatial position, frequency and amplitude can be achieved in real time. A spatial resolution better than 40m is successfully verified in a 1.01 km prototype system of single vibration. Furthermore, the feasibility of detecting and locating multiple vibrations is theoretically analyzed and simulated.