Spectral properties of nonlinearly chirped fiber Bragg gratings for optical communications

Numerical investigation of spectral properties of nonlinearly chirped grating under strain is made. Calculation is performed using Matlab code based on solving the coupled mode equations using transfer matrix method. Our findings show that, by optimizing the linear and higher-order nonlinear chirp coefficients, the reflection bandwidth, side lobes, and group delay could be tunable with the increment of the applied tension. Indeed, the fiber grating chirp is tunable by the applied tension represented by the increase of the reflection spectrum bandwidth and the decrease of the group delay ripples. Besides, the time delay curve typically exhibits two behaviors within the rejection bandwidth: a linear variation for large wavelengths and a quadratic variation for short wavelengths. Therefore, with such kind of grating, it is possible to compensate both linear and nonlinear dispersion in high speed optical networks.