Development Of A Dynamic Demodulation System For Optical Rotation Dispersion Wavelength Based On FPG

In the application of Fiber Bragg Grating sensing,the demodulation of wavelength information is a very important segment,especially in the application of explosion,shock,acoustic emission and other special dynamic signal measurement,the demodulation of Fiber Bragg Grating signal is very difficult,so it is urgent to study the wavelength demodulation scheme for the corresponding sensing signal.A rotatory dispersion wavelength dynamic demodulation system based on FPGA has been proposed,which is composed of rotatory optical path with high extinction ratio,photodetector,high-speed ADC,FPGA,host computer and other parts.On the basis of theoretical analysis,a rotatory dispersion optical path with high extinction ratio and solid-state integration has been constructed;the wavelength demodulation algorithm has been theoretically analyzed and simulated,and the rotatory dispersion wavelength demodulation algorithm has been preliminarily verified in FPGA and PC respectively;the rotatory dispersion principle of quartz rotatory crystal and the rotatory dispersion wavelength demodulation optical path have been experimentally verified by using tunable laser;Verilog HDL program of FPGA data acquisition system is written in Quartus Ⅱ,and the correctness of the program has been verified by Modelsim simulation and SignalTap test;The Matlab GUI upper computer software has been designed to realize the functions of data receiving,transmitting and wavelength signal demodulation;the influence of environmental temperature fluctuation on the wavelength demodulation accuracy of quartz rotatory dispersion has been analyzed,and a temperature compensation method of quartz rotatory dispersion effect using Fiber Bragg Grating temperature sensor has been proposed.To sum up,this design has been based on the rotatory dispersion effect of quartz crystal,combined with high-speed dynamic photoelectric detection and data acquisition and transmission circuit,which lays the foundation for the realization of dynamic wavelength signal demodulation and analysis and processing system.