A novel fiber-optic acoustic vector sensor

A novel fiber optic acoustic vector sensor based on all polarization maintaining fiber optic interferometers is studied, one dimensional pressure-gradient sensor and two dimensional inertial sensor is used to construct the vector sensor. The pressure gradient sensor utilizes two mandrel air cavity pressure sensors with both pressure sensitivity -139dB re.rad/μPa, the inertial sensor is two dimensional push-pull mandrel fiber optic accelerometer with acceleration sensitivity 33dB and 35 dB re. rad/g for each axis. Tests in standing wave tube show that the pressure gradient sensor and inertial sensor both have approximately ideal frequency-response characteristic of pressure sensitivity between 20Hz and 1250Hz, -147.4dB, -153.0dB and -149.9dB@1000Hz for each axis, the results of directivity of each axis show that the vector sensor is of high performance. The particular structure of the novel acoustic vector sensor has intrinsic ability of anti-acceleration in pressure gradient dimension, so it has potential in towed array application.