INVESTIGATION OF THE SPATIOTEMPORAL DEVELOPMENT OF BISTABLE OPTICAL SWITCHING IN THIN CDS CRYSTALS USING A 2-EXCITING-BEAM GEOMETRY

We report the investigation of the spatio-temporal development of the photo-thermal bistable switching process in thin CdS platelets using t wo exciting beams of variable geometry. Transient as well as stationar y regimes are used. The propagation of stable and unstable switching w aves as well as the state of a partial switching are investigated expe rimentally and numerically, solving the heat flow equation. It can be shown that the parameters characterizing the switched area all follow the same rule for the switching down process in stationary and transie nt regimes. Such resemblance disappears for the switching back process in a transient mode. It is further demonstrated experimentally that t he spatio-temporal parameters of the switching process can be controll ed selectively by varying the parameters (intensity, form and polariza tion) of both switching beams.