Experimental Research of an All-Polarization-Maintaining Optical Fiber Vector Hydrophone

This paper reports a new-style all-polarization-maintaining optical fiber vector hydrophone (OFVH) that is composed of a three-component optical fiber accelerometer and an optical fiber hydrophone. In order to make the OFVH small and compact in volume, the orthogonal and unitized structure of the three-component optical fiber accelerometer is adopted. The sensitivity and the operating frequency band of the accelerometer are increased by this proposed structure. The signal fading caused by the random phase shift in the interferometer is eliminated by phase-generated carrier technology. Calibration results show that the acceleration sensitivity is 32.6 dB re rad/g and its fluctuation is less than 1.4 dB over the frequency range of 20-2000 Hz. The phase sensitivity of the optical fiber accelerometer is dB re rad/ Pa at 1000 Hz. This OFVH has an excellent directivity; its maximum asymmetric index is less than 0.4 dB and its directivity index is greater than 45 dB. The excellent performance of this new-style OFVH for use in source localization measurements is also proved by the sea trial.