Electrically tuned phase transition and band structure in a liquid-crystal-infilled photonic crystal

We studied a nematic liquid crystal (LC) cylinder under the action of an axial electric field E-0. Elaborate modeling of the free energy leads to the conclusion that the configuration of the molecules is "escaped radial" for low E-0; a phase transition, however, occurs for a critical value E-c, the configuration becoming axial for E-0 > E-c. From these results, the position-dependent dielectric tensor is determined and the photonic band (PB) structure is calculated for a photonic crystal of LC cylinders. It is shown that by varying E-0 a PB gap can be fully tuned from open to closed. Also, switching to a supercritical field can give rise to interesting polarization and directional effects in the propagation of light.