A 150 Km Distributed Fiber-Optic Disturbance Location Sensor With No Relay Based On The Dual-Sagnac Interferometer Employing Time Delay Estimation

A distributed fiber-optic sensor based on a hybrid configuration of dual-Sagnac interferometer is proposed and demonstrated. The polarization compensation module is used to stabilize the polarization state of Sagnac interferometer so that it can be used for sensing. Through the time delay estimation algorithm, two signals with a time delay can be constructed, and the vibration position can be obtained by extracting the time delay. The experimental results show that the maximum sensing distance of the sensor can reach 150 km and the positioning error is within +/- 30 m. It is easy to install and can be widely used in long-distance security monitoring.