Study On The Nonlinear Characteristiccs Of Fiber Bragg Grating

Fiber Bragg Grating (FBG) is widely applied in the study of fiber laser and amplifier, such as filter, dispersion compensator, WDM device, gain equalizer, etc. These research and application are all related with the linear nature of FBG. In recent years, nonlinear properties of fiber grating have become more important to researchers. Fiber grating soliton can be formed if the nonlinearity of fiber grating is combined with some properties of linear grating. Bistable state and optical switch can be formed if narrowband reflection is combined with nonlinearity and the light pulses compressing can be realized using nonlinearity of grating. But the nonlinearity of ordinary Bragg grating is very low, and it is difficult to obtain high nonlinear properties parameter with conventional means, so it is limited in application. So it is necessary to do in-depth theoretical research on the nonlinear characteristics of FBG and explore new theory and method to improve its nonlinearity. Also, it is expect to realize more extensive applications in optical fiber sensor, optical switch, filtering, etc. through the development and use of its nonlinear characteristics.This paper has done theory and simulation research on bistable state of FBG and the two important nonlinear characteristics of grating soliton, obtained the relation curves about the non-linear characteristics of fiber Bragg grating and optical fiber grating parameters, and studied the method to improve the nonlinearity of FBG. Nonlinearity of Fiber Bragg grating is the main contents of this research, combined with certain scientific research projects Natural Science Foundation of Shandong Province (No.ZR2009AM017). The main content of this paper includes:1, The nonlinear coupling; equations based on coupled mode theory is solved and non-linear bistable switch characteristics of Optical fiber Bragg grating and characteristics of grating soliton are numerical simulated.2. The analytical solutions of nonlinear bistable estate equations according to Jacobi elliptic sine function, Jacobi elliptic cosine function and the third class Jacobi elliptic function is obtained. The nonlinear bistable switch characteristics in the cases of the three solutions are studied.3. The relation curve of switch characteristics and detuning quantity, coupling coefficient, grating length, gain coefficient, switching threshold is obtained. These conclusions can be applied to the analysis and construction of non-linear bistable FBG optical switch.4. The soliton properties of fiber grating are theoretical and simulate studied.