Negative refraction in two-dimensional photonic crystals:: Role of lattice orientation and interface termination -: art. no. 235115

Negative refraction at the interface between air and a two-dimensional photonic crystal is analyzed at frequencies corresponding to the second photonic band. In the study, several lattice orientations and interface terminations of a photonic crystal slab are considered. Finite-difference time-domain simulations are carried out and compared to an analysis using equifrequency contours. The results show that negative refraction and the resulting focusing effects occur under certain conditions but the photonic crystal does not behave in general as an effective refractive medium because the propagation inside the crystal strongly depends on the interface termination. In addition, the Goos-Hanchen effect must be taken into account to obtain the effective index of refraction for a finite photonic crystal slab when negative refraction occurs.