SOLITON SOLUTION OF MNLS/DNLS EQUATION WITH NONVANISHING BOUNDARY CONDITION BASED ON HIROTA METHOD

Hirota's bilinear derivative transformation is a direct method which is more convenient than the inverse scattering transform to deal with a nonlinear partial deferential equation. Based on Hirota's method, the soliton solutions of the modified nonlinear Schrdinger (MNLS) equation under standing wave boundary condition, are obtained; and by simple method of parameter vanishing, the corresponding soliton solutions of the derivative nonlinear Schrdinger (DNLS) equation under constant nonvanishing boundary condition, are gotten, which allows the existence of both bright and dark solitons. The evolution of bright/ dark-soliton solutions in time and space is demonstrated in figures. The results are consistent with what were obtained by the inverse scattering transform.