CONTINUOUS ELECTROOPTIC EFFECT IN TWISTED STRUCTURES OF ACHIRAL SMECTIC-C LIQUID-CRYSTALS

Existence of a continuous electro-optic (EO) effect is predicted in tw isted structures of achiral smectic C liquid crystals (Sm C LCs). In a twist geometry, the smectic layers are formed perpendicular to the su bstrates such that the director is twisted by twice the molecular tilt on going from one surface to the other. In this configuration, the mo lecules are forced to continuously rotate along the cone surface forme d by the requirement that the molecules be tilted with respect to the layer normal and pinned at the surfaces. The basic principles of the o ptical modulation in such devices are similar to those in twisted nema tic LC structures except for the existence of smectic layers and the i ntrinsic biaxiality.