Superfocusing by Nano-Shells

TL;DR

This paper extends super-focusing techniques using nano-shells from microwave to optical wavelengths, providing a generalized design method for arbitrary shapes with potential for arbitrarily sharp focusing within fabrication limits.

Contribution

It introduces a new design procedure for nano-shell scatterers of arbitrary shapes to achieve super-focusing at optical wavelengths, expanding previous microwave-based methods.

Findings

Analytical and numerical validation of the design.

Potential for arbitrarily sharp focusing within fabrication constraints.

Extension of super-focusing concepts to optical range.

Abstract

Recently Merlin and co-workers demonstrated, both theoretically and in the microwave range experimentally, subwavelength focusing of evanescent waves by patterned plates. The present paper extends these ideas and the design procedure to scatterers of arbitrary shapes and to the optical range of wavelengths. The analytical study is supported by numerical results. The most intriguing feature of the proposed design is that, in the framework of classical electrodynamics of continuous media, focusing can in principle be arbitrarily sharp, subject to the constraints of fabrication.