Reflector-type optically controllable light modulators based on smectic liquid crystals

Projection and holographic techniques are used to investigate reflective-ty pe, optically controllable modulators based on an intrinsic a-Si:C:H photoc onductor in which the light-modulating medium is a layer of smectic liquid crystal operating by the deformed-spiral-or-a-helicoid effect. New semicond uctor-light-blocking-layer-mirror structures are proposed. A discussion is presented of how the diffraction efficiency of the modulators is affected b y the properties of two types of multilayer thin-film mirrors based on a-Si :C:H layers with different refractive indices and the oxides HfO2 and SiO2. (C) 2001 The Optical Society of America.