| With the improving technique and the emergence of more and more advance research production, fiber Bragg grating(FBG) had become one of the most successful optic passive device. So developing high-resolution and low-cost FBG demodulator is the key issue of FBG sensors industrializations. The main research of the paper is the linear demodulated technique based on MZ interferometer. At first, FBG and the theory of sensing with FBG are introduced systematically with the characteristics and applications of FBG sensor. Secondly, contrast study of some typical demodulation methods is made. A novel FBG linear demodulation method based on Mach Zehnder interferometer on the basis of traditional linear demodulated technique is proposed. The superiority of the method is the pectinate filter characteristic, that is, the power ratio of the two output arms changes fast with the Bragg wavelength while in the rising or falling edge of the output spectrum. Different steep edge filters can be gotten by adjusting optical path difference (OPD) of MZ interferometer, and the output of the system adopts a kind of normalized ratio to eliminate influence of light source dithering. It is advantageous to get a wavelength displacement detection method with the features as easy to be operated, low-cost, applicable for distributed static measurement, liable to actualize relative detection of all-optical network, and suitable for engineering application. Finally, the optical unit and electric circuits such as photodetector, I-V circuit, processing circuit and low-pass filter circuit of the system are designed and selected in this paper, and then the method is applied to temperature sensing demodulated experiment. Furthermore, the resolution of the experiment system are given, and temperature demodulation experiment is done to validate this solution. In addition, Approach to improve the performance of the system is put forward. This tests indicate that the method is about to be ready for engineering applications.
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