Simulation of vibration induced changed in the fiber Bragg grating reflection spectrum

This study investigates the vibration induced changes in the reflection spectrum of an optical Fiber Bragg Grating. In most cases the strain distribution associated with vibration through the Fiber Bragg Grating length is uniform and the vibration can be measured just by the observation of Bragg wavelength shift in time. But if the strain profile associated with the vibration is not uniform or if there is some primary strain gradient in FBG, not only the Bragg wavelength but also the shape of the reflection spectrum will change. Although the exact simulation of the Fiber Bragg Grating response can be obtained via the couple mode theory and the Runge-Kutta method but they usually require a long running time. Beside the fact that higher convergence speed can be obtained with implementation of transfer matrix method, neglecting the induced chirp created by the distribution field nonuniformities decrease the precision. A modified transfer matrix formulation used in this paper, provides a high accuracy and computationally efficient mean for simulation of a vibration induced change in FBGs reflection spectra.