High-Temperature Fiber Bragg Grating Sensor Array Based on Femtosecond Fiber Grating

In this study, a high -temperature sensing array based on a femtosecond fiber grating was designed to address the temperature measurement needs of high -power spallation targets. The temperature range and mechanical strength of the sensor were enhanced using a femtosecond laser -engraved fiber grating and a tubular encapsulation method. The annealing process, i. e. , annealing steps, annealing time, and annealing temperature, was investigated and optimized. Additionally, multiple annealing (800 & DEG;C , 20 h) was conducted to improve the stability of the fiber Bragg grating. An accurate fitting function of temperature -wavelength was obtained through its calibration test. The sensor has an accuracy of & PLUSMN;0. 2 & DEG;C in the temperature range of 100-500 & DEG;C, with good repeatability. Moreover, on -site testing results indicate that the proposed sensor can achieve precise temperature testing of high -power spallation targets.