SHEAR ALIGNED POLYMER-DISPERSED FERROELECTRIC LIQUID-CRYSTAL DEVICES

Fast switching liquid crystal devices can be produced by forming a dis persion of ferroelectric liquid crystal droplets in a polymer film. Su ch PDFLCs have been fabricated using a polymerization-induced phase se paration technique involving ultraviolet photopolymerization, during w hich the film was sheared to obtain a uniform orientation of the liqui d crystal medium. These birefringence devices show fast response times (sub-millisecond), optimum tilt angle (22.5 degrees), and good contra st (similar to 30:1) at room temperature, using ferroelectric switchin g. We studied the tilt angles, response times and contrast ratio as a function of voltage and temperature to determine the effects of the pr eparation parameters on the electro-optic behaviour of these devices. Using a ferroelectric liquid crystal with long helical pitch, such dev ices appear to be bistable.