Layer structure and electro-optic properties in surface stabilized ferroelectric liquid crystal cells

Abstract

The selective pretilting of the C-directors at the bounding surfaces, which causes characteristic disclination loops during the switching process, has been ascribed to the chevron structure of smectic layers. A zig-zag defect is the boundary between the two possible layer bend directions. By applying an electric field parallel to the substrate plates and the smectic layers, the bold, flat heads of its hairpin part has been identified as the > < type misarrangement, and the bow of a boat-shaped loop has been concluded to contain +2 π wedge disclination. Evolution from focal conics to zig-zag defects has also been discussed. When the spontaneous polarization P_s is very large, the third state has been confirmed to become stable in addition to the bistable, uniform states; this stabilization originates from the chevron structure and the tendency of avoiding the C-director bend deformation which inevitably accompanies the polarization charge - div P_s. In the SA phase of a ferroelectric liquid crystal with large P_s, it has been verified that not only the tilt angle but also the chevron structure is induced by an applied electric field.