Distributed Strain Sensing Based on Combination of Brillouin Gain and Loss Effects in Brillouin Optical Correlation Domain Analysis

摘要

We propose a novel scheme to improve the Brillouin optical correlation domain analysis (BOCDA) system by combining Brillouin gain and loss effects. Periodical chopping of the dc bias of a dual-parallel Mach-Zehnder modulator is used to successively generate upshifted or downshifted single-sideband signal with suppressed carrier. The successively generated signal serves as a Brillouin pump (probe) to amplify (absorb) the carrier for lock-in detection of the net gain between Brillouin gain and loss effects. The signal-to-noise ratio of the novel scheme is twofold enhanced and the feasibility of distributed strain sensing with a nominal spatial resolution of 1.6 cm is experimentally demonstrated.