Interactions among periodic optical solitons for the variable coefficient coupled nonlinear Schrödinger equations

Under investigation in this paper is variable coefficient coupled nonlinear Schrödinger equations for the fiber couplers with asymmetric self-phase modulation and cross-phase modulation. With the developed Hirota bilinear method, bilinear forms and periodic two-soliton solutions are obtained. By choosing different parameters, we have discussed the influences of them on soliton interactions following exponential curve. Two solitons propagate without interaction in the same direction and overtaking collision are displayed. Interactions between solitons propagating in different directions are analyzed. Results provide theoretical guidance for the stable transmission of periodic solitons in the fiber couplers.