Alignment of cholesteric liquid crystals using periodic anchoring

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Abstract
Previous work has shown that when short-pitch cholesteric liquid crystals are aligned in cells with the helical axis in the plane of the substrate in a well-defined direction, then application of an electric field across the cells may result in microsecond in-plane switching due to the flexoelectric effect. Moreover, the response to the electric field is linear and temperature independent. Hence this device geometry has great potential since fast, temperature-independent switching with analogue gray scale may be realized. Up to now, however, the alignment of the helix in the plane of the substrate achieved, for example, by rubbed polyimide layers has been rather unstable, since it relaxes to a Grandjean texture in a time scale determined by the cell thickness. This time is generally of the order of minutes. Here we report a method for the attainment of stable anchoring of the unidirectional lying helix texture using periodic anchoring conditions.