Spatial screening solitons as particles

Photorefractive spatial screening solitons are treated as rays using geomet rical optics. The ray picture is transformed into a classical mechanics pic ture, in which solitons move self-consistently as particles in a potential created by the induced change in the refractive index. The Hamiltonian equa tions of motion are integrated to yield trajectories that agree with the op tical center-of-mass trajectories. The motion in the transverse plane is fo und to be not central and the orbits are not closed, preventing the spirali ng of solitons.