Optically Addressed Liquid Crystalline Light Valves – Theory of their Operation and Applications

Abstract

We report on our research which is focused on developing liquid crystalline optically addressed light valves, their characterization, performances and drawbacks. We study various processes leading to creation of index grating in nematic liquid crystals by incident light. This can be done via molecular reorientation induced by intrinsic photoconductivity of the liquid crystal mixture or by use of semi-transparent photoconducting electrodes containing photochromic dyes. Depending on construction of liquid crystal panels, materials used or even external optical systems several useful optical devices have been constructed, like: phase conjugate mirrors, Fourier optical correlators for pattern recognition, coherent light amplifiers, incoherent-to-coherent light converters, etc. The physical description of these devices must involve the electrical transport properties of liquid crystal used (ion mobilities, photoconductivity, role of dyes and also resistivity of electrode materials, etc.), its optical and mechanical properties (birefringence, order parameter, light scattering, dynamics of molecular reorientation and index profile along the thickness).

Key Words:

• liquid crystal
• spatial light modulator
• real-time holography