Distributed optical fibre audible frequency sensor

A distributed optical fibre sensor is demonstrated which is capable of quantifying acoustic and dynamic strain disturbances along a 1 km sensing fibre. A phase-OTDR technique is used to detect the dynamic perturbations using the phase-difference between the backscattered light from two separate sections of the sensing fibre. The demonstrated sensor detects multiple dynamic perturbations simultaneously within a frequency range of 200 Hz to 5000 Hz with a frequency resolution of 10 Hz and a spatial resolution of 1m