VALIDATION OF THE VARIATIONAL APPROACH FOR CHIRPED PULSES IN FIBERS WITH PERIODIC DISPERSION

We consider the propagation of chirped optical solitons in a fiber wit h periodic dispersion and describe this by a variational approach assu ming a single pulse ansatz. We obtain a good agreement between the var iational equations and the full numerical solution for the low-frequen cy region below the fundamental resonance. In that case we study the n onlinear resonances and chaotic oscillations of the pulse width and wi th this analysis we can predict the stochastic decay of pulses under a periodic modulation of the dispersion. For the main resonance and res onances above it, this simple variational approach fails because of a strong emission of linear waves. Then the numerical solution decays sl owly while the simple model predicts a fast breakup. In the high-frequ ency limit the pulse is stable and we can describe it via averaged var iational equations for its width and chirp, which we derive. We show t hat this dynamical model yields interesting physical estimates for sol iton propagation in a fiber with dispersion management. [S1063-651X(98 )12110-4].