Reduction Method of Sinusoidal Noise due to Phase Drift of Interferometric Optical Fiber Hydrophone

This paper describes a method of reducing sinusoidal noise due to a phase drift of an interferometric optical fiber hydrophone based on the fiber Bragg grating (FBG). An FBG-based interferometric optical fiber hydrophone is based on path-matched differential interferometry conducted with a compensating interferometer. Then, if the ambient temperature of the hydrophone is not equal to that of the compensating interferometer, a sinusoidal noise due to a demodulated phase drift of the interferometer occurs. To reduce this sinusoidal noise, it is proposed that the compensating interferometer be controlled by a supplementary Peltier device. The feedback-controlled compensating interferometer cancels the influence due to the difference between the ambient temperature of the hydrophone and that of the compensating interferometer. The effectiveness of the feedback-controlled compensating interferometer combined with the Peltier device is verified through waterpool experiments.