Soliton collision and soliton fusion in dispersive materials with a linear and quadratic intensity depending refraction index change

The collision of two-valued (or two-state) solitons with a frequency shift is investigated. Solitons of the lower solution branch behave in a manner similar to that of solitons in the case 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