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.