SRI-Immune Highly Sensitive Temperature Sensor of Long-Period Fiber Gratings in Ge-Sb-Se Chalcogenide Fibers

This work exhibits design and characteristic study of highly sensitive temperature sensors of long-period fiber gratings (LPFGs) in Ge-Sb-Se fibers. Temperature characterization of the designed LPFGs with different working modes, operating wavelengths, and surrounding refractive indices (SRI) were studied. Results showed that temperature sensitivity of the proposed Ge-Sb-Se LPFGs reached 0.5787 nm/at 1.55 mu m at the lowest LP02 cladding mode, which is approximately 12 times higher than silica LPFGs and 1.2 times higher than that of As-Se LPFGs. When grating period of the designed Ge-Sb-Se LPFG was selected at its dispersion-turning-point, temperature sensitivity reached a maximum absolute value of 24.715 nm/degrees C. Influences of operating wavelength and temperature sensitivity of these LPFGs on SRI are extremely weak due to relatively high refractive index of Ge-Sb-Se fiber, indicating that the designed Ge-Sb-Se LPFG temperature sensor possesses extremely strong sensing stability on SRI.