Acoustic field modeling and experimental research of an overflow cavity fiber optic hydrophone based on COMSOL simulation

Abstract

The fiber-optic hydrophone, with the characteristics of high sensitivity, easy multiplexing and long transmission distance, is becoming a new direction for the development of the underwater detection system. The overflow cavity type optical fiber hydrophone is composed of a sensitizing inner shell, a rigid outer housing, sensing optical fiber and other auxiliary structures. It is a small-size and high-sensitivity hydrophone in the form of the air-backed sensitized structure, which could be applied to new towed array and fixed array system. In this paper, the acoustic performance of the hydrophones in different sound fields was simulated using the COMSOL finite element analysis. In the light of the design of the overflow cavity type optical fiber hydrophone, the acoustic field distribution of the hydrophone surface and the strain distribution of the optical sensing fiber were analyzed and compared with the free sound field model and the standing wave field model. And the sensitivity response of the hydrophone was predicted. On this basis, the sample of the overflow cavity type optical fiber hydrophone with the same design parameters was developed, and the sensitivity test was carried out in the standing wave tube. The experimental results show that the test frequency is 315 Hz to 2 kHz, the phase shift sensitivity of the hydrophones is -143 dB ref.1 rad/μPa. The difference between the test results and the simulation results is less than 1.5 dB under 1kHz.