Particle-optical self-trapping

The formation of a self-guided beam pattern via optical trapping in a suspension of Rayleigh scatterers is studied. An analytic self-guided solution is presented that is valid for low intensities. A numerical solution of the coupled diffusion and optical-wave equations is presented, which shows an evolution toward a steady state that is independent of the initial optical beam shape. At higher intensities, the numerical solution shows the influence of higher-order nonlinearities, which lead to instability. We define a critical optical intensity, in terms of the particle size, refractive index contrast, and thermal energy, that characterizes the onset of higher-order effects. Instability is found that is consistent with past parametric studies of solitons.