All polarization-maintaining fiber optic hydrophone based on phase generated carrier modulation/demodulation technique

The experimental result of all polarization-maintaining fiber optic hydrophone based on phase generated carrier modulation/demodulation technique was presented. Because of polarization-maintaining fiber structure, the system gets rid of instability of polarization. A phase generated carrier scheme is used to demodulate the interferometer output to reduce the optical phase shift. The fiber optic hydrophone attained stable acoustic signal and had the character of all optical fiber. The phase sensitivity of the fiber optic hydrophone is -162.5 dB and undulation of the phase sensitivity is 1.4 dB in the frequency range from 20 Hz to 1600 Hz, while undulation of the phase sensitivity at 500 Hz is not greater than 0.1 dB.