Switching dynamics in nonlinear directional fiber couplers with intermodal dispersion

The nonlinear directional coupler (NLDC) is studied in terms of intermodal dispersion (IMD). The system of the coupled nonlinear Schrodinger equations (CNLSE) of the coupled-mode theory is the mathematical model utilized to describe the NLDC. The strong relationship of this model with the normal-mode theory is discussed. The study is focused on the propagation of fundamental solitary pulses. Optical pulses are launched only in one of the two input ports of the coupler resembling, thus, a common situation in an actual lightwave system. Several numerical simulations are performed and conclusions on the impact of the IMD on the transmission of the NLDC are extracted. A clear picture of how the IMD influences the unity of the fundamental solitary pulse is thus obtained. (C) 2004 Elsevier B.V. All rights reserved.