Fiber sensing scanner system based on A-thermal fiber bragg gratings

This study is to achieve a new interrogation system for fiber Bragg grating (FBG) sensors, wavelength demodulation is commonly performed using a Fabry-Pérot (FP) scanner. However, for the thermal effects to a FP scanner, using a single A-thermal FBG as the reference to extract the correct sequence index and position of FBG sensors is introduced. In addition, a third-order polynomial curve fitting function is used to account for the nonlinear relationship between the FP driving voltage and the FP transmission wavelength. To enhance the accuracy of the FP scanning system, an additional interrogation structure based on four A-thermal reference FBGs is also proposed and the proposed interrogation system can accurately extract the Bragg wavelength down to 7.2 pm. Also, the performance of a FP scanning system with a high-end or low-end FP scanner is discussed.