An equivalent circuit model of Optically Addressed Spatial Light Modulator (OASLM) incorporating Ferroelectric Liquid Crystal (FLC) is proposed. The model is used in studying gray-scale response of the OASLM and intensity transfer characteristics while drive voltage frequency varying from 100~1 kHz and write-light intensity varying from 0~10 mW/cm

2

. The results indicate that the rise time of electro-optical responses decreases from 1.44 ms to 74 μs as write-light intensity increases from 0.5 mW/cm

2

to 10 mW/cm

2

. It also indicates that write-light intensity has a range over which gray-scales are best produced since output-light intensity increases linearly or nearly linearly with write-light intensity in this region. The intensity transfer characteristic is highly dependent on drive voltage frequency which can be set to adjust the region producing gray-scales

the slope of intensity transfer characteristic in the region producing gray-scales

and so forth. When write-light intensity increases from 0.5 mW/cm

2

to 10 mW/cm

2

the gray-scale range (0.08 mW/cm

2

1 mW/cm

2

) is changed to (2 mW/cm

2

10 mW/cm

2

)

and the slope of intensity transfer characteristic in the region is decreased. Furthermore

although intensity transfer characteristic is weakly dependent on erase-light intensity

the erase-light is necessary to restrain the unexpected optical response when write-light is not injected and ensure a proper erasure of the device. The simulation results from the model have shown good agreement with the reported experimental results in both magnitude and tendency.