Design of an optically addressed spatial light modulator sensitive to 1.55-μm write light

Abstract

Most optically addressed spatial light modulators (OASLMs) utilize photosensors of hydrogenated amorphous silicon (a-Si:H), Si, GaAs, CdS, CdSe or other photosensors which are sensitive from visible to near IR wavelengths (< 1.1 µm). Some applications such as correction of atmospheric turbulence in the eye-safe region of the spectrum for free-space optical communication demand OASLMs that have high sensitivity at 1.55 µm, high frame rate (> 1 kHz), and high resolution (MTF = 50% at 40 lp/mm). Ferroelectric liquid crystal (FLC) has very fast response and FLC OASLMs can be operated at frame rates of a few kHz[l]. An IR-OASLM with an In0.53Ga0.47As-InP photosensor and an FLC light modulating layer is being developed in our laboratories. The design, preliminary experimental results, and practical issues for such an IR-OASLM will be presented and discussed.