Electro-Optical Effects in Other Phases of Liquid Crystals

ELECTRO-OPTICAL EFFECTS IN OTHER PHASES OF LIQUID CRYSTALS 

Although by far nematics are the most extensively used ones, other phases (smectic, cholesteric, etc.) of hquid crystals and mixed systems such as polymer-dispersed liquid crystals capable of field-induced reorientation have also been employed for electro-optical studies and applications. They are basically based on the same basic mechanism of field-induced director axis reorientation similar to nematic hquid crystals i.e., the response is Kerr like in that it is independent of the direction of the electric field. In general, nematic liquid crystal electro-optics devices switch at a rate of several terrs of hertz, corresponding to response times from a few to tens of microsecorrds. 

On the other hand, ferroelectric liquid crystals operate very much like Pockel cells their response depends linearly on the applied electric field vector, that is, they depends on both the magnitude and direction of the electric field. They generally switch faster than nematic cells. To date ferroelectric liquid crystals possess a switching speed of 1 ps or less. 

---