Alignment of the Uniform Lying Helix Structure in Cholesteric Liquid Crystals

Abstract

The uniform lying helix (ULH) configuration in cholesteric liquid crystals, where the helical axis of a chiral nematic is aligned uniformly in the plane of two confining substrates is of interest for both electro-optic and photonic applications. However, the formation of the well-aligned ULH structure required is non-trivial. Since the helical axis tends to align at an angle with respect to the surface alignment direction, cells where both substrates have planar alignment layers can cause the formation of a two-domain ULH structure. Here we investigate the orientation and nature of the domains as a function of field application. Further we show that it is possible to obtain mono-domain structures when the alignment directions on each substrate are skewed so as to match the angle that the helix forms with respect to the alignment at the electric field applied. This improves the electro-optic contrast of devices.