Impact of the laser spectral purity on high-resolution distributed acoustic sensing based on optical frequency domain reflectometry

We present our recent results on the impact of the laser performances on a high-resolution distributed acoustic sensor using a phase resolved optical frequency domain reflectometry. Two tunable laser sources with equivalent modulation capabilities but different noise characteristics are implemented in an interrogator configured to sense a 1 km fiber with 10 cm spatial resolution at a 3 kHz repetition rate. A deskew filter is used to compensate sweep nonlinearities in post-processing. We first study the impact of the laser noise on static traces, before exciting the fiber with a piezo stretcher at 300 Hz in comparable experimental conditions. We confirm that laser phase noise is limiting the sensing performances once the backscattered intensity is maximized.