Model of a two-dimensional photonic bicrystal - art. no. 045101

Assuming a stack of two layers of one single dielectric anisotropic materia l, a crystallographic twist between the layers results in a dielectric cont rast at the interface. If the one-dimensional stack is considered to have a discrete translational symmetry along the direction of light propagation, the periodic structure resembles a dielectric Bragg stack. Extending the co ncept of dielectric contrast by crystallographic contrast in two or more di mensions, an interesting type of photonic crystal is developed. Due to the anisotropic nature of the proposed structure, the optical properties vary b y changing the crystallographic twist of the layers, and by changing the di rections of the lightflow. In directions of sufficiently large dielectric c ontrast, propagating electromagnetic modes are confined in regions of high and low dielectric constants. In directions of zero or low dielectric contr ast, the electromagnetic modes are coupled, and light propagates through a continuous transparent medium. The photonic band structures of a two-dimens ional photonic bicrystal are calculated for different bicrystalline structu res. Guidelines for the design of photonic bicrystals by twist wafer bondin g are included.