Abstract
This paper examines the nonlinear effects of alpha and gamma changes on the motion of photon in a Fiber Bragg Grating. The study has been successfully performed out under Bragg resonance condition where the initial frequency of the light has the same value with the Bragg frequency. The Stokes parameter is chosen to provide important information on the total energy and energy difference between the forward and backward propagating modes. The motion of a particle moving is shown using the classic anharmonic potential where beta is set to zero for power conservation along the grating structures.