Focusing light with a single subwavelength aperture flanked by surface corrugations

In this letter, we show theoretically how a single subwavelength aperture surrounded by a finite array of grooves made on a metallic film can act as a lens for electromagnetic radiation within a certain frequency range. The dependence of this resonant focusing ability with the geometrical parameters defining the structure is extensively analyzed. Universal curves for the depth, length and width of the focus as a function of the number of grooves are also given. (C) 2003 American Institute of Physics.