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We have investigated the in-plane switching of cholesteric liquid crystals for reflective wavelength shifters for visible and near-infrared applications. These devices are based on the elongation of the cholesteric pitch by an electric field perpendicular to the helical axis. The transmission notch-reflection peak position can be tuned continuously to a longer wavelength (redshift) by application of an in-plane electric field. The helix is completely unwound when the electric field is higher than the cholesteric-to-nematic transition field, and the sample is transformed to a transparent state. We have investigated the electro-optic performance of in-plane switching of cholesteric samples and developed a simple phenomenological model to describe the underlying electro-optic phenomena.

We report a holographic polymer-dispersed liquid crystal cell whose reflection peak can be tuned as a function of applied voltage. Electro-optic results are presented which are in excellent agreement with our model based on coupled wave theory.

We report single-layer holographic polymer-dispersed liquid-crystal materials with multiple reflection and/or diffraction gratings. Three switchable gratings are observed in a single film formed in a three-beam interference pattern. Two reflection gratings and one transmission grating are formed, corresponding to each of the three possible two-beam interference fringes. We present scanning electron microscopy and electro-optic results which are in good agreement with our model based on matrix methods and coupled-wave theory.