Resolution Enhancement in Brillouin Optical Correlation Domain Analysis by Differential Lock-in Detection

Abstract

We newly propose and experimentally demonstrate a differential lock-in detection scheme for the enhancement of Brillouin optical correlation domain analysis (BOCDA), where additional phase modulation is applied to the Brillouin pump wave and the on-off control on which is used for data acquisition. The theoretical model and the experimental results show that at least three-fold improvement is obtained in the spatial resolution of the distributed measurements and the Brillouin gain spectrum (BGS) with much narrower 3dB bandwidth than that of conventional BOCDA systems is acquired by the differential lock-in detection.