HELIX DEFORMATION AND BISTABLE SWITCHING OF FERROELECTRIC LIQUID-CRYSTALS

We studied electro-optical properties of 5-13-mu m-thick films of a sh ort pitch (0.43 mu m) chiral smectic C liquid crystal in bookshelf str ucture. The anchoring at the silane treated surfaces was relatively we ak so that the relaxed bookshelf structure was helical also at the sur faces. Low fields cause only a deformation of the helix. Larger fields unwind the helix and give a quasibistable switching since the helix r ecovers at zero fields only slowly via a nucleation process. There is an intermediate field range where the sample is in a mixed state: In s ome areas the helical structure remains stable, while in other areas s witching occurs between two unwound states. In the intermediate field range bistable switching with a gray scale is possible. (C) 1996 Ameri can Institute of Physics.