Phase Noise Mitigation in Continuous Chirp Phase-sensitive OTDR with Digital Filtering

Laser phase noise is detrimental to the sensing performance in continuous chirp phase-sensitive optical time domain reflectometry (CC Phi-OTDR). In this work, we theoretically analyze the effect of the phase noise on the sensing performance and use a Lorentzian filter to mitigate the impact of the laser phase noise. Compared to the raw signal, the proposed method improves the sensing accuracy by approximately 9 dB at the 22-km position.