Dynamical optical near-gap solitons

Nonlinear optical medium with periodically modulated refractive coefficient is considered. New two-parametric soliton solutions are found with frequencies, lying near the gap of linear waves spectrum of the system. Such near-gap solitons propagate with velocity varying from zero to its maximum value, which is defined by medium properties. The evolution of the system phase portrait with change of the nonlinear excitation frequency (Omega) is also studied. Moving algebraic solitons, which separate two types of two- parametric solitons, namely gap and near-gap, are also considered.