Subwavelength imaging by metallic slab lens with nanoslits

A metallic slab lens featured with specially designed nano slits is presented to realize imaging for arbitrary object and image distances. Based on the particular propagation properties of surface plasmon polaritons in nanostructures, slits perforated in silver slab are designed with variant widths to produce desired optical phase retardations. Numerical simulation of an illustrative lens is performed through finite-difference time-domain method and shows that subwavelength imaging is realized at the designed position.