Dark and bright soliton exchange in a nonlinear dispersive medium

The interactions; between solitons and kinks in the nonlinear Schrodinger e quation with a generalized nonlinearity are studied. The system has bright- soliton, dark-soliton, and kink solutions. Among them, the kinks play the r ole of a domain wall dividing the space into self-focusing and self-defocus ing regions. Numerical analysis shows that the bright (dark) solitons can b e exchanged into dark (bright) ones upon collisions with kinks, directly sh owing the reciprocity between the two classes of solitons.