Design of a meta-screen for near-zone field focalization at optical frequencies

In this letter, we propose the design of a nano-circuit reactive artificial screen for the synthesis of a given field pattern with sub-wavelength features at visible frequencies. The meta-screen consists of a discrete set of dielectric cells, behaving as lumped reactive elements. The cells have been designed according to the recently proposed new concept of metactronics. The spatial distribution of the cells, and the inter-element electrically small spacing enables the focalization of a sub-wavelength spot beyond the diffraction limit at a prescribed focal distance. The design is supported by full-wave simulations, showing the actual focusing properties of the artificial screen proposed.