A High-Performance Fiber-Optic Hydrophone for Large Scale Arrays

In this paper, to develop a high-performance fiber-optic hydrophone for large-scale hydrophone arrays, a general sensing model is theoretically built from mandrel-wound structures of fiber-optic hydrophones. By analyzing and optimizing the structural parameters of the model, a high-performance fiber-optic hydrophone is designed from two aspects. First, the structure of the mandrel is optimized by elastic theory and finite element analysis approach, and the structural design of fiber-optic hydrophone with high acoustic pressure sensitivity and wide frequency response range is realized. Then, the winding ratio of the fiber is optimized by mathematical simulation to realize an Omni-directivity fiber optic hydrophone design. The feasibility of the designed fiber-optic hydrophone is further experimentally demonstrated. The results indicate that the proposed hydrophone achieves a high average acoustic pressure sensitivity of $-$ 113 dB ( $re$ 1 rd $/$ $\mu$ Pa) within the flatness of $\pm$ 1.5 dB from 10 Hz to 1000 Hz, and a horizontal directivity of $\pm$ 1 dB at 1 kHz. Moreover, the average minimum detectable acoustic pressure is achieved as low as 14.1 $\mu$ Pa. The capability of weak acoustic signal detection and large-scale multiplexing offers great potential for application in underwater faint target detection.