Analysis Of Dynamical Response Characteristics Of FBG

Fiber Bragg Grating(FBG) is a kind of linear and passive device. It is low-power, and fully compatible with optical fiber with small size and high precision and it is applied to optical telecommunication and optical sensor field as dispersion compensator, filter, OADM, temperature sensor, pressure sensor and so on more and more extensively. With deeper research into the FBG theory and improved manufacture technology, not only the linear characteristics of FBG get applied, but the FBG show great potential as the nonlinear component.The origin and development and various appliance of FBG in optical telecommunication and optical sensor field is explicitly introduced in this paper. It follows that the deduction of nonlinear coupled-mode equations from Maxwell equations, which precisely describes the Coupled-mode Theory of fiber grating mathematically. To solve the equations without analytical solutions, a numeric method based on the combination of coordinate-transformation and finite difference is depicted and an implementation based on it is arrived with avoiding coordinate-transformation on the solution. By making use of this realization-based Matlab programme, the linear and nonlinear dynamical characteristics of Bragg fiber are analyzed. Firstly the dynamic response feature of the reflectivity of average, Gauss- and Cosine-apodized FBG is analyzed and compared for continuous wave input, and then the reflective and transmitted figure of three kinds of FBG under Gaussian pulse input.