Study on polarization maintaining fiber Bragg grating strain sensor

The special polarization maintaining fiber Bragg grating(PMFBG) with fusion spliced joint was proposed to overcome the cross-sensitivity of the temperature and the axial stain. The structure introduced a bulge by splicing the two fibers, then the FBG was inscribed symmetrically in the middle of the fusion spliced joint. The special PMFBG was manufactured by panda polarization-maintaining fiber and the reflection spectra was measured under 0~2N axial stress. It is found that the reflection spectra of the fast and slow axis split to two peaks respectively and shift towards the longer wavelength side with increasing axial stress, the ratio of the peaks decreases at the same time and is not affected by the temperature. Moreover, the axial strain character of the structure was simulated by the finite element method, and the reflection spectra of the PMFBG were calculated by the transfer matrix method. The simulation and experimental results are in good agreement, verifying that the peak ratio of the PMFBG reflection spectrum can be used to eliminate the cross-sensitivity of axial strain and temperature, and the measurement of axial strain can be realized.