Negative refraction and subwavelength imaging of a photonic-crys...

Negative refraction and subwavelength imaging properties of a two-dimensional (2D) photonic crystal (PC) slab are studied by the finite-difference time-domain method. The PC consists of a triangular lattice of air holes immersed in a dielectric. For a certain frequency range in the third photonic band, the directions of the group velocities and the phase velocities can be opposite, so the PC can work as a kind of negative refractive-index material. The light radiated from a point source can form