Experimental and theoretical analysis of the self-focusing of light by a photonic crystal lens

We demonstrate the self-focusing of electromagnetic waves in the microwave regime by using a two-dimensional photonic crystal lens with rectangular shape. A detailed study of the band structure shows that the focusing is due to the refractivelike behavior of the photonic crystal with a negative effective index of refraction in the frequency range under study. In contrast to lenses based on homogeneous isotropic materials, it is shown that the symmetry of the mode and the direction of incidence play a fundamental role in the performance of the photonic crystal lens.