Bistable reflective polarizer-free optical switch based on dye-doped cholesteric liquid crystal [Invited]

The work demonstrates a polarizer-free bistable reflective electro-optical switch that is based on dichroic dye-doped cholesteric liquid crystal (DDCLC). Bistable opaque and transparent states can be achieved using the planar and ULH textures of CLC, respectively. In the planar texture, the liquid crystal and dye molecules have a periodic helical structure with axes perpendicular to the substrate surface. They therefore absorb arbitrarily polarized light. In the ULH texture, the liquid crystal and dye molecules twist along the helical axes parallel to the substrate, and allow most of the arbitrarily polarized light to pass. Both the planar and ULH textures of CLC are stable states, and each can be switched to the other by applying a low-frequency (30Hz) electrical field, owing to the electro-hydrodynamic effect. A bistable electro-optical switch has the advantages of being polarizer-free and consuming low power. It can therefore potentially be used in portable information systems.