[Research on the phase-shifted fiber grating spectrum characteristics in the inhomogeneous strain fields]

Based on the transfer matrix method, the spectrum characteristics of phase-shifted fiber grating were analyzed systematically, and the reflection spectra of phase-shifted fiber grating under uniform strain, linear strain, secondary strain and cubic strain were simulated respectively. The regularity conclusion that the influence of different strain distribution functions on reflectivity, transmission bandwidth, wavelength of transmission window and spectral shape came out. In order to verify the simulation result, strain-tuning equipment was designed based on cantilever with different structures. Finite element method was carried out to simulate the strain distribution of phased shift fiber grating fixed on the surface of cantilever during the strain-tuning experiment. Experiment result demonstrated that the reflection spectra of phase-shifted fiber grating under uniform strain, linear strain and secondary strain exhibited a regular change, which is in agreement with simulation results.