Negative refraction in two-dimensional photonic crystals

Recently, the phenomena of negative refraction and left-handed behavior in two-dimensional photonic crystals (PCs) have been investigated systematically. We find that the PCs consisting of coated cylinder possess some new characters that those do not exist in pure dielectric and metal system. Absolute negative refraction regions for both polarizations of electromagnetic wave in these systems have been found. Especially, absolute all-angle negative refraction for both polarizations has also been demonstrated. Thus, the focusing and image of unpolarized light can be realized by a microsuperlens consisting of these 2D PCs. These new phenomena had never been observed before our works appeared. Furthermore, high-quality images and focusing, with relative refractive index of -1, have been observed in these systems for both polarized waves. In contrast to the images in near-field region for the lowest valence band, non-near-field images, explicitly following the well-known wave beam negative refraction law, have also been demonstrated. Thus, extensive applications of such a phenomenon to optical devices are anticipated.