Liquid crystals as materials for real-time holographic optical devices

This paper describes low-molecular-mass liquid crystals doped with suitable dyes which can be used for real-time holographic purposes. We describe the origins of the diffraction gratings or holograms induced by a light intensity pattern in a dye-doped nematic liquid crystal sandwiched between two conducting glass plates. The mechanism is linked to electric-field-driven reorientation of the nematic director. The modulation of the electric field is induced mainly by the bulk photoconductivity of the system. Design and characterization (response time, diffraction efficiency) of the optically addressed spatial light modulator (OA-SLM) is presented. Interesting applications of these materials enabling phase conjugation and optical correlation are discussed.