Single-measurement digital optical frequency comb based phase-detection Brillouin optical time domain analyzer

Abstract

A single-measurement sweep-free distributed Brillouin optical time domain analyzer (BOTDA) sensor based on phase detection is proposed and experimentally demonstrated employing digital optical frequency comb (DOFC) probe signal. Brillouin Phase Spectrum (BPS) of DOFC probe induced by Brillouin interaction is measured using coherent detection in a single acquisition, without any frequency scanning and data averaging. Single-measurement BOTDA sensor based on BPS in 10km long fiber is demonstrated with a response time of 100 mu s, which is limited only by the fiber length. The spatial resolution is 51.2m, determined by the duration of DOFC. And the Brillouin frequency shift (BFS) uncertainty is estimated to be similar to 1.5 MHz at the end of fiber under test (FUT). Benefiting from the fast response time, dynamic measurement up to 1 kHz vibration frequency has been demonstrated.