Waveguiding, collimation and subwavelength concentration in photonic crystals

By means of both finite elements and FDTD calculations, we demonstrate that a structure of photonic crystal, constituted by two dimensional arrays of dielectric cylinders in air, or viceversa, previously proposed as capable of producing negative refraction with superlensing properties and subsequently proved to lack this characteristic, do possesses however the property of giving rise to effects of total internal reflection that allow both waveguiding, bending and collimation with high intensity subwavelength concentration of wavefronts. This is a consequence of both the dominant propagation along the Gamma M direction due to diffraction, and of intensity localization in the cylinder regions as a result of the operating frequency being in the lower part of the bandgap, namely, in the so-called dielectric band. (c) 2005 Optical Society of America.