Non-conventional alignment surfaces for antiferroelectric liquid crystals

Antiferroelectric liquid crystals(AFLC)feature interesting properties for a number of photonic applications. However, alignment of planar structures of these materials using conventional alignment layers is not satisfactory. One of the main problems dealing with these materials is the limited alignment obtained with standard manufacturing procedures, and the contrast decrease in multiplexed devices derived from the presence of pretransitional effect. The influence of alignment layers on AFLC contrast and switching has been studied. Using different alignment materials or manufacturing processes, it is possible to obtain different threshold voltage, dynamic range, and time response for the same material. We have studied the influence of alignment in two kinds of AFLC materials, namely regular tristate AFLCs and orthoconic AFLCs. Regular tristate materials feature long pitch and relative small cone angle. Contrast is not very good, but dynamic switching properties are excellent. Orthoconic materials are short pitch, wide cone angle(90degrees)materials. Contrast is excellent(200-300), but dynamic behavior is below regular materials.