A Novel High-temperature Sensor Based on Fiber Bragg Grating

Optical fiber sensor is the most common type of temperature sensors due to its suitability for high temperature, strong radiation environment and so on. A novel high-temperature sensor based on fiber Bragg grating (FBG) is proposed in this paper. The radiation resistance and mechanical strength of the sensor are improved by both an irradiation-resistant FBG inscribed by femtosecond laser and tubular packaging technology. Then, the annealing process considering of annealing steps, annealing time and annealing temperature is studied. The stability of FBG is greatly improved by the many times of high-temperature and long-term annealing (700°C, 20h). Finally, the high-temperature response of sensor is studied, and the temperature-wavelength fitting functions of FBG are obtained. The experimental results show that the temperature measurement range is from 0 to 500°C, the measurement accuracy of the sensor is about ± 0.6°C. The FBG sensor is expected to be used for high-temperature measurement in extreme environments such as aeroengines, high-speed aircraft, and nuclear reactor cores.