Self-Organized Periodic Photonic Structure in a Nonchiral Liquid Crystal

A hybrid-aligned cell of the smectic A liquid material 8CB gives two stable director configurations, one of which is periodic and gives strong diffraction of light. This photonic lattice director profile arises from "frustration" caused by conflicting constraints imposed by the boundary conditions and the constant amplitude smectic density wave. A model is proposed which accords well with the experiment results, predicting correctly the dependence of the periodicity on the cell thickness and reproducing optical polarization microscopy results.