Asymmetric optical Y junctions and switching of weak beams by using bright spatial-soliton collisions

We show that a collision between two bright spatial solitons acts as an asymmetric optical Y junction and, in specific cases, as an optical switch for the weak beams that they guide. The output energy of the probe beams in each optical channel can be controlled by adjustment of either the relative direction or the phase of the two colliding solitons or by a change in the wavelength of the probe beams. A physical description of such behavior based on the diffraction of the incident probe beams by a diffraction grating formed by the spatial-soliton collision profile is presented.