Subwavelength focusing of light in the planar anisotropic metamaterials with zone plates.

We present here a structure with just a single slit covering the planar anisotropic metamaterial. The metamaterial has hyperbolic dispersion and can be realized using metal-dielectric multilayers. The structure combines the focusing performance of the zone plates and subwavelength resolution of the anisotropic metamaterials so that subwavelength focal spots can be obtained at the focal plane. The relationship between the focal spot size and slit width has been investigated, and a resolution of 36 nm about 1/10 of 365 nm incident wavelength is obtained with a 100 nm wide single slit.