Investigations on the Laser Spectral Purity in High-Resolution Distributed Acoustic Sensors Based on Optical Frequency Domain Reflectometry

We recently proposed a distributed acoustic sensing (DAS) architecture based on phase-sensitive optical frequency domain reflectometry (φ-OFDR) and a deskew filter to post-process the chirp non-linearities [1]. The cornerstone is a frequency modulated solid-state (FMSS) laser [2]. With the development of frequency modulated lasers on photonic integrated circuits [3], we started investigating the impact of the laser spectral purity on DAS measurements. We here present our first results comparing our FMSS laser with a commercially available semi-conductor (SC) laser designed for frequency modulation in a similar high-resolution dynamic <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\varphi-{}$</tex> OFDR setup (10 cm spatial resolution over 1 km, 3 kHz interrogation rate).