High Sensitivity Distributed Vibration Sensor Based on Polarization-Maintaining Configurations of Phase-OTDR

A system based on all-polarization-maintaining configurations of the phase-sensitive optical time-domain reflectometry (OTDR) is presented for vibration sensing. Both polarization-induced signal fading and noise are mitigated via polarization-maintaining components. The detectable frequency response is increased to ~2.25 kHz. Moreover, only a straight sensing fiber segment of ~0.13 m instead of several closed fiber loops is needed to sense the vibration event with a spatial resolution of 1 m, which makes it convenient for vibration monitoring in practical applications. The maximum distance between the sensing fiber and vibration event can be 18 cm.