The influence of fiber inhomogeneity on the positioning accuracy of distributed fiber vibration sensor

摘要

Fiber inhomogeneity induced random birefringence in single mode fiber (SMF) can lead to the polarization fading effect in distributed fiber vibration sensor using Mach-Zehnder interferometry. By considering the contributions of both visibility and phase noises in interference output signal, the influence of polarization fading effect on the position accuracy of distributed vibration sensor using cross-correlation algorithm is theoretically derived. A new term of equivalent signal to noise ratio (SNR_e) is defined in the model. Based on the theory, a novel method for decreasing the positioning error of low-frequency vibration signal is given and verified by field test results.