Abstract
The effect of nonlinear parametric known as alpha (alpha), beta (beta) and gamma (gamma) has been successfully calculated and a new effect of theta (theta) is introduced to describe the motion of photon in a fiber Bragg grating as a factor of external disturbance. This study is developed under Bragg resonance condition where the initial frequency of the light,. 0 is the same value as the Bragg frequency, omega(B). We found that the potential well is not symmetric and conserved.