A spatially shifted beam approach to subwavelength focusing

TL;DR

This paper introduces a novel metal transmission screen with subwavelength slots that achieves near-field focusing beyond the diffraction limit, scalable across frequency regimes, supported by analytical, simulation, and experimental validation.

Contribution

It proposes a new spatially shifted beam method using a metal transmission screen for subwavelength focusing, overcoming losses in negative-refractive metamaterials.

Findings

Achieves subwavelength focusing beyond diffraction limit

Analytical model matches full-wave simulations

Experimental validation at microwave frequencies

Abstract

Although negative-refractive-index metamaterials have successfully achieved subwavelength focusing, image resolution is limited by the presence of losses. In this Letter, a metal transmission screen with subwavelength spaced slots is proposed that focuses the near-field beyond the diffraction limit and furthermore, is easily scaled from microwave frequencies to the optical regime. An analytical model based on the superposition of shifted beam patterns is developed that agrees very well with full-wave simulations and is corroborated by experimental results at microwave frequencies.