Aperiodic Phase-Only Sampled Chirp Gratings with High Reflectivity for Compensating the Dispersion and the Dispersion Slope

For compensating the chromatic dispersion and the dispersion slope simultaneously, an optimization method is presented to design aperiodic phase-only sampled gratings. To obtain a low insert loss, all sub-gratings with the same reflectivity of 99.9% and the different dispersion values are synthesized using the layer-peeling algorithm. By using the simulated annealing algorithm, an optimal set of the relative phases for each of the equally spaced sub-gratings can be found to reduce the difference between the minimum and the maximum values of the amplitude of the sampling function. Then, the Gerchberg-Saxton algorithm is applied to eliminate the amplitude modulation of the sampling function. As a result, the aperiodic phase-only sampled chirp grating is finally obtained. This multi-channel grating can compensate precisely the dispersion and the dispersion slope of an 80Km fiber link over WDM channels.