Distributed optical fiber vibration sensing using phase-generated carrier demodulation algorithm

摘要

A novel optical fiber-distributed vibration-sensing system is proposed, which is based on self-interference of Rayleigh back-scattering with phase-generated carrier (PGC) demodulation algorithm. Pulsed lights are sent into the sensing fiber and the Rayleigh back-scattering light from a certain position along the sensing fiber would interfere through an unbalanced Michelson interferometry to generate the interference light. An improved PGC demodulation algorithm is carried out to recover the phase information of the interference signal, which carries the sensing information. Three vibration events were applied simultaneously to different positions over 2000 m sensing fiber and demodulated correctly. The spatial resolution is 10 m, and the noise level of the Phi-OTDR system we proposed is about 10(-3)rad/root Hz, and the signal-to-noise ratio is about 30.34 dB.