Electrically switchable polymer-stabilized cholesteric diffraction gratings

We present the structure of electrically switchable diffraction gratings using low concentration polymer network stabilized pattern-forming state (fingerprint texture) of a host cholesteric liquid crystal. In this polymer-stabilized cholesteric diffraction grating (PSCDG)s, both the pattern-forming state and its diffraction state are the result of complex combinations of dielectric, flexoelectric, and electrohydrodynamic torques induced by applying an electric field at specific amplitudes and frequencies and for specific ratios of the sample thickness to cholesteric pitch. In each case, key structural features of the patterned distortion in orientational order of the liquid crystal can be recorded into the morphology and optical anisotropy of an internal polymer network, which is formed via photopolymerization of a low concentration monomer additive. The observed morphologies reported in this paper include one-dimensional arrays of thin parallel and zig-zag walls. We also discuss issues how the polymer network enhances the potential of complex pattern-forming states in liquid crystals for optical beam steering and switching applications.