Optimization of gray-scale performance in pixellated-metal-mirror FLC-OASLM by equivalent circuit model

An equivalent circuit model of a pixellated-metal-mirror ferroelectric liquid crystal (FLC) optically addressed spatial light modulator (OASLM) is proposed. Using both structure and FLC material parameters of a real device and real material as the simulation parameters, the model is firstly confirmed by good agreement of simulation results and the reported experimental ones, and then utilized to optimize gray-scale performance of the OASLM. The model is developed from an improved FLC equivalent circuit, and has the ability to describe the voltage dropped across the modulating layer and to predict how optical outputs vary over time with the input drive voltage and control image. Simulation results indicate that gray-scale performance of the OASLM is highly dependent on write pulse width. More than 10 gray scales are observed when write pulse width is 100 μs and the number reduces to four when it reaches 500 μs. Other parameters of drive voltage can be set to adjust the region of write light intensity over which gray scales are best produced, and write pulses are found to be primary at high write light intensities, whereas erase pulses are dominant at low write light intensities. Furthermore, although gray-scale performance is weakly dependent on erase-light intensity, the erase light is necessary to ensure a proper erasure of the device and at least 1 mW/cm2 is required in this study.