Gradient Index Metamaterial Based on Slot Elements

TL;DR

This paper introduces a gradient-index metamaterial made of annular slot arrays that can be used to create compact, high-contrast lenses for terahertz radiation, demonstrated through simulations.

Contribution

It presents a novel annular slot-based GRIN metamaterial enabling large refractive index variation with few layers, suitable for THz lens applications.

Findings

Achieved an index contrast of Delta n = 1.5

Designed a 3-unit-cell thin GRIN lens for THz

Focused THz radiation to sub-wavelength spot size

Abstract

We present a gradient-index (GRIN) metamaterial based on an array of annular slots. The structure allows a large variation of the effective refractive index under normal-to-plane incidence and thus enables the construction of GRIN devices consisting of only a small number of functional layers. Using full-wave simulations, we demonstrate the annular slot concept by means of a 3-unit-cell thin GRIN lens for the terahertz (THz) range. In the presented realizations, we achieved an index contrast of Delta n = 1.5 resulting in a highly refractive lens suitable for focusing THz radiation to a spot size smaller than the wavelength.