Liquid crystal spatial light modulators for optical interconnects and space switching

Many schemes for parallel optical interconnects involve the use of spatial light modulators (SLMs). Advances have occurred in liquid crystal technology that promise major improvements in the performance of SLMs. These are not based on electro-optic effects in the familiar nematic and cholesteric phases, but on a number of newer electro-optic effects in chiral smectic liquid crystals. The authors examine two of these electro-optic effects; the so called ferroelectric switching in chiral smectic C liquid crystals and electronic switching in chiral smectic A phases. They assess their prospects in electrically addressed spatial light modulators and emphasise the problems of obtaining in large arrays of pixels the same performance as can be obtained from single pixels. A hybrid technology, combining chiral smectic liquid crystals and silicon VLSI, is proposed as a means of obtaining addressable structures of large arrays of pixels. The problems and prospects of this hybrid technology are briefly reviewed