Switching dynamics of solitons in fiber directional couplers

A simple analytical approach based on a variational formalism is applied to an analysis of the switching dynamics of solitons in fiber nonlinear directional couplers. It is demonstrated that soliton switching may be described by a simplified Hamiltonian model that displays three different regimes of soliton dynamics, depending on the universal parameter, which is the ratio of the squared intensity nu(2) to the coupling parameter kappa. It follows from the analysis presented that perfect soliton switching may be achieved only for the case nu(2)/kappa < pi/2.