Distributed vibration/acoustic sensing with high frequency response and spatial resolution based on time-division multiplexing

A novel time-division multiplexing scheme is proposed and demonstrated for distributed vibration/acoustic sensing with broad frequency response range and high spatial resolution. By setting the time delay between a narrow pulse and a quasi-continuous wave properly, conventional phase optical time-domain reflectometry and polarization diversity scheme can be combined without crosstalk to determine position and frequency of vibration event, respectively. Detections of high vibration frequency of 0.6 MHz and low frequency of 1 Hz are presented with 1 m spatial resolution over 680 m single-mode sensing fiber.