Adaptive Waveguides Using Photorefractive Creening Solitons

Abstract

Photorefractive screening solitons appear when self-focusing inside a photorefractive material exactly balances the diffraction of the propagating light beam. The refractive index change induced by these solitons can effectively guide other beams and therefore spatial photorefractive solitons can be used as adaptive waveguides. In time resolved measurements we show that a HeNe-probe beam exactly follows the trajectory of the inducing beam. If two incoherent solitons are launched simultaneously, strong interaction effects (attraction, repulsion, rotation, energy exchange) occur due to their common anisotropic potential. These effects offer the possibility of using photorefractive solitons for the realization of different waveguide devices such as switches, dividers or couplers. For this purpose an exact knowledge of the soliton trajectories during propagation is indispensable. We realized a time- and spatially resolved examination of the interacting solitons, which gives a detailed insight into the trajectories of the beams. Furthermore we present the successful guidance of a probe beam in interacting photorefractive solitons with and without mutual exchange of energy and therefore the realization of an adaptive all-optical switch and a l-to-2-coupler using photorefractive solitons.