oa Long Range Distributed Acoustic Sensor with Phase Noise Compensation

In this work, we propose a novel phase noise compensation (PNC) method aiming at mitigating impact of the laser phase noise on DAS, by deploying an auxiliary interferometer together with an appropriate two-step compensation algorithm. In experimental demonstration 100 µs linear frequency modulation (LFM) laser pulses are injected into sensing fiber without any optical amplification under different strategies (PNC on / off). Strain resolution of 55 pε/√Hz with 47 km measurement distance and 4.3 m spatial resolution is realized in demonstration system. The concept-proof experiment suggested that our PNC scheme provides an effective solution for long range DAS facing the nonideal light source phase noise level.