Optically addressed electroclinic liquid crystal spatial light modulator with an a-Si:H photodiode

A fast optically addressed spatial light modulator (OASLM) is demonstrated using a p-i-n photodiode of hydrogenated amorphous silicon (a-Si:H) and the electroclinic effect in chiral smectic A liquid crystals. The response time depends on the material and the temperature. We used a material with a response time of 40 μs at 29°C and 4 μs at 51°C. This work shows that there is an excellent match between a-Si:H photodiodes as photosensors and high speed liquid crystals as electrooptic modulators. The optical response varies with the field and write-light intensity, allowing for grey level applications.