Liquid Crystalline Soft Materials with 3-Dimensional Periodic Structure

Abstract

The blue phases (BPs) are kinds of liquid crystal (LC) phases that appear in a temperature range between a chiral nematic phase and an isotropic liquid phase. Since BPs have a three-dimensional cubic structure with lattice periods of several 100 nm, they exhibit the selective Bragg reflections in the range of visible light corresponding to the cubic lattice. From the viewpoint of the application, although BPs are of interest for fast light modulators or tunable photonic crystals, it has been a problem that the temperature range of BPs is very narrow, usually less than a few K. The stabilization of BPs was shown over a larger temperature range than 60 K (260 K-326 K) across the room temperature. Furthermore, an electro-optical switching with a response time on the order of 10^-4 s was demonstrated for the stabilized BPs at room temperature. Here, fundamental properties and recent topics on BPs are reviewed.