Quasi-distributed acoustic sensing with DSB-OFDR for large measurement range and enhanced frequency response

We demonstrate a quasi-distributed acoustic sensor with a large measurement range and high-frequency response, based on time-frequency-multiplexing double-sideband optical frequency domain reflectometry (TFMDSB- OFDR) and a weak reflectors array. The Doppler frequency method detects vibration signals by measuring Doppler shifts caused by vibrations, enabling detection of signals with exceptionally large amplitudes. Combined with the time-frequency multiplexing scheme, the system’s frequency response is enhanced. In the experiment, the system achieves a sampling rate of 500 kHz, a 50-fold increase.