On the robustness of optical solitons in the presence of periodic amplification

Abstract
Nonlinear optics is a paradigm for the importance of solitons in non-Hamiltonian systems. An asymptotic analytical approach for optical solitons in the presence of loss and rapidly varying periodic gain in fibers is proposed. It is shown that up to terms of order epsilon2/q4 (where epsilon and q are the amplitude and frequency of the rapidly varying periodic gain, respectively) the averaged nonlinear dynamics can be effectively analysed in terms of a renormalized nonlinear Schrodinger (NLS) equation. The propagation of the sech-type input pulse is discussed, and it is shown which new effects might be expected dealing with the averaged dynamics instead of that described by the unperturbed NLS equation. The analytical results are confirmed by direct numerical simulations showing a good agreement with the theory.