Multipath Quasi-Distributed Acoustic Sensing Based on Space Division Multiplexing and Time-Gated OFDR

Quasi-distributed optic sensing system has been widely used in various applications for its simple configuration, high sensing resolution, and long sensing range. In large sensing network, multipath sensing arrays are needed to be monitored simultaneously. This article proposes a multipath quasi-distributed acoustic sensing system based on time-gated digital optical frequency-domain reflectometry (TGD-OFDR) and space division multiplexing (SDM) technique. The single-mode fiber (SMF) segment between weak reflectors is efficiently used. In experiments, vibrations on two weak reflectors array are detected simultaneously, and crosstalk between paths is analyzed. This multipath system does not require additional hardware equipment and the bandwidth of the system is not sacrificed, which has great potential in large-scale sensing network.