Research on the characteristics of a twisted high birefringence fiber grating

Abstract:

A novel torsion sensor, which can be embedded in the engineering material, is proposed. Based on the coupled mode theory and the characteristic of twisted high birefringence fiber, we have established the mathematical model of twisted high birefringence fiber grating transfer matrix. Two numerical simulation methods based on the transfer matrix method and coupled mode theory were used to analyze the consequent changes in reflection spectra. The simulation results of the two methods show good agreement with each other. The two main peak wavelengths of the high birefringence fiber grating shift as the twist angle changes from 0 to 360. And a peak was produced among the wavelengths of two main peaks. Its wavelength basically does not change and is about 1552.225 nm. Its corresponding reflected peak valueR _c basically presents the linear relationship with the twist angle α. The experiments show that the system has a wide measurement range. The resolution is 0.012° and the sensitivity is 0.13/rad. Good agreements between experimental results and numerical simulations have been obtained. Supported by National Natural Science Foundation of China (60377002)