BOTDA sensor utilizing digital optical frequency comb based phase spectrum measurement

Abstract

An Ultra-Fast Sweep-Free distributed BOTDA sensor is proposed and experimentally demonstrated employing coherent de-modulation of digital optical frequency comb (DOFC) probe signal. The phase shift of each frequency tone induced during the Stimulated Brillouin Scattering (SBS), corresponding to the Brillouin Phase Spectrum (BPS), is simultaneously measured in a single shot without frequency sweeping and averaging. We demonstrate an ultra-fast BOTDA sensor in10km long fiber with the measurement time of 10 ìs, which is depending on the time-of-flight of the fiber. The minimum detectable fiber length is 51.2m with a 1.95 MHz frequency resolution among 1 GHz sensing coverage. The BFS uncertainty of our ultra-fast BOTDA using BPS is calculated to be~1.5 MHz near the end of fiber under test (FUT), which is significantly improved by ~50% compared with that using BGS.