Alignment-Controlled Holographic Polymer Dispersed Liquid Crystal for Reflective Display Devices

Abstract

A new type of holographic polymer dispersed liquid crystal (HPDLC) device in which liquid-crystal (LC) alignment is controlled by polymerized layers has been developed. In the alignment-controlled HPDLC device, the polymerized regions (polymer layers) are formed periodically in homogeneously aligned LC. When an electric field is applied vertically between the substrates, the LC molecules in the residual regions (LC layers) rotate towards the electric field. This causes a difference in refractive index between the polymer layers and LC layers, so selective reflection occurs in accordance with Bragg's law. The selectively reflected light shows strong polarization dependence. Only light polarized parallel to the alignment direction of LC molecules is reflected.