Study On Spectrum Characteristic Of Fiber Grating In Non-Uniform Temperature Filed

Fiber Grating is one of the passive fiber devices that have been developed most quickly in recent years. It's an important milestone in the history of Fiber Technology. Fiber grating sensing is one of the important fields in fiber grating application. Now temperature, a very crucial factor in many situations, makes the temperature sensors indispensable. Temperature measure is one of the important fleild of fiber grating sensors.Basing on the period longth of the fiber grating, we usuall call the fiber grating that period is less than 1μm as short period fiber grating, we olso call it as fiber bragg grating(FBG) or refrective grating; We call the fiber grating that the period is about many decades to many hundrdeds as long period fiber grating(LPFG) or transmission grating. The paper analysis the spectral characteristics of this two fiber gratings in non-uniform temperature fields.First, the paper describe the fiber grating in concept,the development of history, the research actuality in domestic and foreign, and the problems of fiber grating sensor in development and application.Secondly, the paper analysis the theoretical model of fiber grating, and detailed analysis the theory of coupled mode, the transfer matrix method, as well as temperature characteristics of FBG and LPFG.Finally, in this paper, based on the transfer matrix method, we simulate the spectrue characteristict of FBG and LPFG and analysis the result of simulation using MATLAB. We discuss the effection on PFG's and LPFG's spectrue characterasric of the different parameter, such as different kinds of non-uniform temperature, the length of fiber grating, the positive or negative of the wavelength temperature sensitivity and the modulation coefficient.Many papers have disscused the spectrue characterastics of fiber grating in the uniform temperature fileds. In common situation, the temperature is not a constant. The papers of mersuring non-uniform temperature are extraordinary few. In this paper, we systems analysis the spectrue characteristic of fiber grating in non-uniform temperature filed.