Modeling and experimental research on receiving signal of multi-layer distributed acoustic sensing optical fiber in shallow water

Abstract

To better apply the distributed acoustic sensing optic fiber (DASF) based on phase-sensitive optical time domain reflection (Ф-OTDR) to underwater target detection, on the basis of the two-layer optical fiber model, the single-mode optical fiber model composed of core, one-layer cladding and multi-layer coatings is established, which is closer to the reality. Based on this model, the receiving signal model of DASF is set up. The relationship between the phase change of backward Rayleigh scattering (BRS) signal in optical fiber before and after the disturbance caused by acoustic field is derived. Experiment in the lake is carried out, which results show that the data received by the underwater distributed optical fiber system can better reconstruct as the acoustic source information in shallow water, and the feasibility of DASF sensing underwater acoustic signals in shallow water is verified. The rationality of receiving signal model of DASF is verified by comparing the simulation modeling with the experimental results.