Theoretical analysis of acoustic sensitivity of mandrel fiber optic hydrophone with fiber optic layer

This paper analyzes and investigates the acoustic sensitivity of mandrel fiber optic hydrophones (FOHs) with fiber optic layers (FOLs). Sensitivity models for both single-column and push-pull air-backed structures influenced by the FOL were established, and simulations were conducted to compare the theoretical acoustic sensitivity of mandrel structures with and without the FOL. Three sets of single-column FOHs and two sets of push-pull FOHs were fabricated using different materials and tested. The experimental results show that: in the model considering FOL, the deviation between theoretical and measured values for different material mandrel structures is controlled within 1.5 dB; in the model neglecting the FOL, the maximum deviation between theoretical and measured values of the polyurethane single-column probe reaches 29.2 dB, and the maximum deviation between the theoretical and measured values for the polycarbonate push-pull probe reached 4.29 dB. Therefore, this model can more accurately estimate the acoustic sensitivity of mandrel structures with lower Young's modulus, providing guidance and reference for the design of high-sensitivity mandrel FOHs.