Design and Implementation of Dual-Edge Filter Demodulation System Based on the Dual LPFG and Embedded Technology

This investigation aims to design and implement an dual-edge filter fiber grating sensor demodulation system based on the dual Long Period Fiber Grating (LPFG) and embedded technology. The principle of linear dual-edge filter is introduced first, and the system architecture and runtime logic is designed and implemented based on the MCU system architecture. The LPFG is employed as the linear filtering equipment. As filter output differs when reflection light passes filters of different spectral characteristic, the Logarithm operation of light intensity ratio can be used to calculate the wavelength. Experiments demonstrate that this system designed in this investigation can stably demodulate the FBG sensor signals. The difference between linear fitting computation value and optical spectrometer measured value is 10pm, the dynamic rage is 4nm. The results indicate that the linearity is good and accurate is high, and this method provides valuable reference for engineering wavelength calibration and debugging.