Study On Temperature Sensing Demodulation System Based On Matching Fiber Bragg Gratings

With the development of the communication network, the optical fiber sensing technology iswidely concerned, especially optical fiber grating sensor, it has so many big advantages,such asanti-interference capability, corrosion resistance, high temperature resistant, high sensitivity, signalbroadband and so on to occupy the communication market. Optical fiber grating center reflectionwavelength changes with optical fiber grating period and effective index, and optical fiber changeswith grating period, effective index and external conditions such as temperature, strain and so on,according to this characteristic, we can test out the change of external conditions through the opticalfiber grating reflection wavelength and the variation of articles. So the fiber grating sensingtechnology is widely used in military, environmental testing, large buildings and oil fields.This paper mainly uniform fiber Bragg grating (FBG) as the research object. It has theoreticalresearch and experimental verification for optical fiber grating theory, tuning technology andmatching fiber grating demodulation system, the main content includes:(1) It introduces the development of optical fiber Bragg grating sensing technology and theapplication of fiber Bragg grating, a brief analysis of the writing methods and the characteristics ofthe fiber Bragg grating sensor. It is learned the different types of optical fiber grating characteristicsthrough optical fiber grating is classified. Then it introduces fiber grating sensing demodulationtechnology.(2) Fiber grating coupling mode theory is analyzed, the interpretation of the two waveguidesbehavior. According to Maxwell equation derived coupling mode equation, it is concluded that fibergrating Bragg conditions and reflectivity formula.(3) The fiber grating center wavelength tuning technology is discussed, specially discusses thetemperature tuning and strain tuning. Both of two can pass the modulation grating period andeffective index for the purpose of turning the optical fiber grating center wavelength. Thetemperature sensing experiments of bare grating and organic glass packaged grating are studied.(4) The matching fiber grating filter demodulation principle is discussed, with optical fibergrating tuning technology as the foundation, use and sensing fiber grating matching other opticalfiber grating tracking sensing fiber grating wavelength change, by changing the temperature forsensing grating wavelength changes, and the wavelength change detection scheme validation.