Optical Fiber Hydrophone Based on Distributed Acoustic Sensing

Based on the principle of phi-sensitive optical time domain reflectometry (phi-OTDR), the distributed optical fiber acoustic sensing (DAS) system can detect long distance and real-time acoustic signal by demodulating the phase change of backward Rayleigh scattering in the single mode fiber. Low sensitivity of single-mode fiber limits the underwater acoustic signal detection. In this paper, we design an elastic sensitizing layer base element encapsulation structure, and establish a theoretical analysis model. The theoretical analysis and experiment are carried out, the sensitivity of the acoustic pressure sensitivity of the elastic sensitizing layer structure is -141.6dB re 1rad/mu Pa, which is in good agreement with the theory.