Optical Structures and their Control in a Liquid-Crystal-Light-Valve Experiment

We review the conditions for the control of optical structures in a nonlinear optical experiment, which is a Liquid-Crystal-Light-Valve with optical feedback. The optical structures we deal with may be either localized states or spatially extended patterns. Indeed, the localized structures here described represent the localized solutions of a pattern-forming system. We will show that there exists different regions of existence of such localized states, and that different types of localized structures can be selected depending on the choice of the control parameters. Localized states, stable for some range of parameters, are in general characterized by complex spatio-temporal dynamics. In the same way, spatially extended patterns show space-time chaotic behaviors. We show that pattern targeting and control may be achieved by adding an extra control loop to the experiment. Different target patterns can be stabilized in real time and synchronization between space-time chaotic signals is demonstrated.