Fiber Bragg grating hydrophone with polarization-maintaining fiber for mitigation of polarization-induced fading

Abstract

In this paper, we describe an interferometric optical fiber hydrophone using a pair of fiber Bragg gratings (FBGs) with a polarization-maintaining fiber (PMF). Signal fading induced by random fluctuations in the state of polarization for interfering beams of a fiber interferometer is a common problem for all interferometric optical fiber sensors. To overcome this signal fading problem, a PMF was utilized to construct an interferometric optical fiber hydrophone using a pair of FBGs. Then the performance of the PMF hydrophone was compared with that of a conventional single-mode optical fiber hydrophone. In our experiment, we adopted a 3-3 coupler scheme for the demodulation of acoustic signals to reduce the computational load required for the demodulation scheme, and the effectiveness of the proposed optical fiber hydrophone with the 3-3 coupler scheme was confirmed. © 2012 The Acoustical Society of Japan.