Principle and design approach of flat nano-metallic surface plasmonic lens

The principle of a flat nano-metallic surface plasmonic lens is analyzed based on phase matching and effective refractive index theory. The complex relationships between the macro-parameters such as focal length with other design freedoms, e.g. material properties of the lens, sheet thickness, slit width, and slit pitch, are disclosed as well. A set of tailored formulae are derived for the design of such a nano-metallic surface plasmonic lens. Several simplified implementations of the nano-metallic lens such as a lens with equidistant slits but bearing different widths, and a lens with equal slit widths but different pitches are given. The performance of the beyond-diffraction-limit focusing effect is given as well. PACS 02.60.Cb; 78.20.Ci; 71.36.+c; 78.68.+m