Sub-wavelength focusing meta-lens

TL;DR

This paper demonstrates a plasmonic meta-lens capable of focusing transmitted light into sub-wavelength hot-spots beyond the near-field, utilizing superoscillation phenomena, achieved through nano-structuring a gold film.

Contribution

It introduces a novel plasmonic meta-lens design that achieves sub-wavelength focusing beyond the near-field using superoscillation.

Findings

Achieved 160 nm focal spots at 800 nm wavelength.

Demonstrated sub-wavelength focusing beyond near-field.

Linked superoscillation to hot-spot formation.

Abstract

We show that planar a plasmonic metamaterial with spatially variable meta-atom parameters can focus transmitted light into sub-wavelength hot-spots located beyond the near-field of the metamaterial. By nano-structuring a gold film we created an array of meta-lenses generating foci of 160 nm (0.2{\lambda}) in diameter when illuminated by a wavelength of 800 nm. We attribute the occurrence of sub-wavelength hotspots beyond the near field to the phenomenon of superoscillation.