Abstract
Optically-addressed spatial light modulators (OASLMs) utilizing a hydrogenated amorphous silicon photodiode as the photosensor and a ferroelectric liquid crystal as the modulator show great promise in high-speed, high-contrast spatial light modulation. We present the initial design, modelling, and performance of such devices. The devices are driven by a square-wave voltage, such that write and read operations take place under reverse bias, and an erase operation occurs under forward bias. Under continuous write-beam illumination the optical modulation is determined by the photoconductivity of the photosensor under forward bias. During chopped write-beam illumination the modulation is produced by the photocurrent produced under reverse bias. We find an increase in the contrast with reduced bias voltage, which is explained in terms of a series capacitance effect. Several polarization-based logic gates are described which utilize a single OASLM devices.