Optical left-handed metamaterials made of arrays of upright split-ring pairs

TL;DR

This paper introduces a novel optical left-handed metamaterial made of upright split-ring pairs that exhibits negative refraction, high figure of merit, and broad bandwidth, advancing the design of optical negative index materials.

Contribution

It proposes a new design of optical left-handed metamaterials using upright split-ring pairs, achieving superior electromagnetic properties at near-infrared frequencies.

Findings

Refractive index of -2 achieved

Figure of merit of 21 demonstrated

Negative refraction confirmed in simulations

Abstract

Electromagnetic metamaterials are man-made structures that have novel properties such as a negative refraction index, not attainable in naturally occurring materials. Although negative index materials (NIMs) in microwave frequencies were demonstrated in 2001, it has remained challenging to design NIMs for optical frequencies especially those with both negative permittivity and negative permeability [known as left-handed metamaterials (LHMs)]. Here, by going beyond the traditional concept of the combination of artificial electronic and magnetic meta-atoms to design NIMs, we propose a novel LHM composed of an array of simple upright split-ring pairs working in the near infrared region. Our electromagnetic simulations reveal the underlying mechanism that the coupling of the two rings can stimulate simultaneously both the electric and magnetic resonances. The proposed structure has a highest refractive index of -2, a highest figure of merit of 21, good air-matched impedance and 180 nm double negative bandwidth, which excel the performances of many previous proposals. We also numerically demonstrate the negative refraction of this metamaterial in both the single-layer form and wedge-shaped lens.