Numerical investigation of negative refraction effect in two-dimensional photonic crystal fabricated in gallium nitride

We investigated the conditions for obtaining negative refraction in photonic crystals fabricated in gallium nitride (GaN). Negative refraction at the interface between air and two-dimensional photonic crystals was numerically analyzed using Plane Wave Expansion Method (PWE) and Finite Difference Time Domain Method (FDTD). To describe the origin of negative refraction we have carried out simulations of equifrequency surfaces (EFS) of each photonic crystal structure. The presence of negative effective refractive index has been shown in two dimensional photonic crystal with hexagonal lattice of air holes etched in GaN. We have also observed all-angle negative refraction without existence of negative refractive index for 2D photonic crystal with square lattice of air holes. Additionally, the superlensing effect as a potential application of negative refraction in two dimensional photonic crystal was simulated.