Fiber grating sensor demodulation method based on polarization interference

A novel wavelength shift detection scheme for use in fiber Bragg grating sensing systems is proposed. The structure of the polarization maintaining fiber loop mirror is studied and its theoretical model is established. In addition, the distribution characteristics of the input light wavelength and the output power are analysed. Moreover, numerical simulation and experimental validation are also performed. The results show that the device has simple structure, high stability and high detection precision. The measuring range and the precision can be adjusted by varying the parameters of the fiber loop mirror. In the demodulation range larger than 1 nm, the average precision of the wavelength demodulation is lower than 1 pm.