Design of resistant static pressure probe for DFB fiber laser hydrophone

In the deep working environment, the hydrostatic pressure can cause the reflection center wavelength of distributed feedback (DFB) fiber laser hydrophone drifting out of the multiplexing window of demodulation system, and the target sound pressure signal cannot be demodulated by the water receiver; different hydrostatic pressures also cause changes in the sensitivity of the distributed feedback fiber laser hydrophone, which affects the consistency of the fiber laser hydrophone array. Based on the theory of electric sound analogy, a distributed feedback fiber laser hydrophone probe with static pressure compensation was proposed. The sound pressure transfer function of the structure was established, and the influence of various structural parameters on the transfer function was analyzed, which provided a theoretical basis for the flattening design of the frequency response for distributed feedback fiber laser hydrophone probe. The resistant static pressure distributed feedback fiber laser hydrophone sample was processed and tested. The fluctuation range of sound pressure sensitivity was no more than ±2.4 dB in the frequency range of 0 kHz～10 kHz, and the wavelength drift of the exiting laser center within 2.3 MPa was no more than 0.06 nm. The results are of guiding significance for the research of deep water fiber laser hydrophone.