Interaction of spatial solitons in biased photorefractive photovoltaic media

Numerical investigations of the interactions among bright screening-photovoltaic solitons are performed in detail by using the Crank-Nicholson scheme. The numerical results show that a number of parameters, such as the initial separation and phase difference between solitons, can determine the interaction forces of solitons. The numerical study indicates that two in-phase solitons attract each other, and soliton fusions do occur at certain interaction length. The distance of the soliton fusions increases monotonously with the increment of initial separation between two solitons. On the other hand, two interacting beams repel each other when they are 180 degrees out of phase, the force of repulsion between them decreases monotonously with the increase of their initial separation. While the phase difference between two solitons is in the ranges of (0,pi) or (-pi,0), the situation is more complex because the power is transferred between the two solitons. Moreover, interactions among multiple solitons are also investigated.