| Fiber Bragg Grating (FBG) is one of the most studied of the fiber grating.Compared with sensors based on other principles, FBG sensors have several distinguishing advantages, such as, excellent electric insulation, resistance of the interference of electromagnetic, high sensitivity. FBG sensor is widely used in the aviation industry, civil engineering, electric power industry, the oil industry, the medical industry, and so on. FBG sensors are one of the most exciting developments in the field of fiber-optic sensors in recent years. Although kinds of demodulation techniques have been developed, most of them have not yet met the requirements of the practical application. FBG sensing signal demodulation system based on tunable fiber Fabry-Perot filter method is designed in this paper.Firstly, the coupled-mode theory and the sensing principle of fiber Bragg grating is analyzed, Bragg formula and the sensing principle Formula between the temperature or the strain and the center wavelength of the fiber Bragg grating are deduced.Distinguish technology between the temperature and strain and Parameter performance of fiber Bragg grating sensor are analyzed and studied.By comparing several kinds of fiber Bragg grating demodulation method, this paper choose tunable Fabry-Perot filtering method. Analysis the working principle and characteristic parameters of tunable Fabry-Perot filter,and calibration of the relationship between the driving voltage of the filter and the center wavelength of fiber Bragg grating. Analyzed the performance of broadband light source in the sensing system.The module circuits of the system are designed, such as, photoelectric conversion circuit, amplified circuit, shaping circuit and capturing signal circuit based on PIC. A mathematical model is given to calculate the sensing FBG center wavelength, and simulation is conducted using Lab VIEW. The experimental results are consistent with theoretical analysis, which conform the feasibility of the demodulation system. |
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