SOLITON COLLISION AND SOLITON FUSION IN DISPERSIVE MATERIALS WITH A LINEAR AND QUADRATIC INTENSITY DEPENDING REFRACTION INDEX CHANGE

In dispersive materials with saturable or higher-order nonlinear refraction index change under certain conditions two-valued (or two-state) soliton solutions exist, which describe undistorted pulses with the same duration but different peak power. In this paper the collision of such solitons with a frequency shift is investigated. Solitons of the lower solution branch behave similar as in the case of a Kerr-nonlinearity and retain their shape. In contrast, two solitons of the upper solution branch with a low frequency shift fuse to a single high-energy soliton after the collision. For larger frequency shifts after the collision three or more pulses appear. The results can also be used for the description of two-state bistable spatial soliton collisions in planar waveguides. In this case two colliding solitary light beams can fuse to a single beam with a changed propagation direction. The possible applications of the investigated effects for nonlinear photonic switching are discussed.