HOMEOTROPIC TO TWISTED PLANAR TRANSITION IN NEMATIC LIQUID-CRYSTALS WITH NEGATIVE DIELECTRIC ANISOTROPY

We have studied the effect of molecular chirality and cell gap on the electro-optic (EO) modulation associated with a homeotropic to twisted -planar (HTP) transition. It is found that an optimum condition of the cell gap and the corresponding chirality exists for the maximum EO mo dulation. A surface layer of the KTP structure is somewhat thicker tha n that of a conventional twisted nematic one. The helical pitch predom inantly governs waveguiding characteristics and the resultant EO prope rties of the HTP structure. The polar and azimuthal surface anchoring on treated homeotropic alignment layers is also discussed.