Patterns, fronts and structures in a Liquid-Crystal-Light-Valve with optical feedback

Finally, a more fundamental approach to the liquid crystal physics is presented, showing how the Fréedericksz transition becomes a first-order one in the presence of a light-driven feedback. In the corresponding experimental regime, instead of patterns there are fronts connecting different metastable states. When the bistability coexists with pattern formation, due to the diffractive feedback, stable localized structures can be excited in the system, either in the form of isolated or bound states. Highly ordered clusters of localized structures may also be obtained by choosing a close recurrence for the feedback rotation angle. Recent results on the dynamics of localized structures are reported, showing a complex radial and azimuthal motion along concentric rings, as selected by the diffractive feedback.