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

Abstract

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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 113 dB ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$re$</tex-math></inline-formula> 1 rd / <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> Pa) within the flatness of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 1.5 dB from 10 Hz to 1000 Hz, and a horizontal directivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 1 dB at 1 kHz. Moreover, the average minimum detectable acoustic pressure is achieved as low as 14.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> Pa. The capability of weak acoustic signal detection and large-scale multiplexing offers great potential for application in underwater faint target detection.