Study on temperature sensing properties of different fiber Bragg grating at low temperature

In this paper, in order to understand the fiber Bragg grating (FBG) sensor´s temperature sensing properties with different coating materials and packaging materials at low temperature, and choose a FBG sensor for engineering application, an experimental platform is designed at first, the temperature sensing performance of five different type of FBG sensors at low temperature (77K-296K) is studied, and then the wavelength-temperature curve and temperature sensitive coefficient curve of these five FBG sensors is analyzed. At last, a nonlinear fitting for the best wavelength-temperature curve is made to provide a reference for practical application. It is concluded that polyimide-coated FBG sensor can be used normally at low temperature, and the temperature sensitive coefficient increases 4.32pm/K as reference to bare FBG, packaging has few effect on the sensor´s performance of grating sensors. The OS4200 whose wavelength-temperature curve´s cubic curve fitting is better than quadratic curve fitting has high accuracy and good stability, it can meet the requirement in practical engineering.