Coherent-detection-assisted BOTDA system without averaging using single-sideband modulated local oscillator signal

Abstract

A novel setup for coherent-detection-assisted Brillouin optical time domain analysis (BOTDA) is proposed and demonstrated. Performance enhancement is enabled by a power-controllable local oscillator (LO) generated using single-side-band (SSB) modulation. Through employing a commercial coherent receiver and polarization diversity scheme, the Brillouin gain traces carried on a stable intermediate frequency (IF) are obtained in real time without any averaging and processed by digital signal processing (DSP) without the need of ultra-narrow optical band pass filter. A spatial resolution of 4 m and frequency uncertainty of 1.473 MHz are achieved over 40 km sensing range using a single scan.