Robust wedge demonstration to optical negative index metamaterials

TL;DR

This paper introduces a robust wedge setup to clearly demonstrate negative refraction in optical metamaterials, providing a new method to verify negative index properties and estimate material losses.

Contribution

The paper presents a novel wedge demonstration method for negative refraction, including a quantitative approach to estimate material loss and a design for visible-range negative index metamaterials.

Findings

Successfully demonstrated negative refraction in various optical metamaterials.

Derived a simple expression to estimate wedge material loss.

Designed a visible-range negative index metamaterial compatible with nano-imprinting.

Abstract

A robust wedge setup is proposed to unambiguously demonstrate negative refraction for negative index metamaterials. We applied our setup to several optical metamaterials from the literature and distinctly observed the phenomena of negative refraction. This further consolidates the reported negative-index property. It is found there generally exists a lateral shift for the outgoing beam through the wedge. We derived a simple expression for calculating this beam shift and interestingly, it provides us a strategy to quantitatively estimate the loss of the wedge material (Im[n]). Addition- ally, we offered a design of metamaterials, compatible with nano-imprinting-lithography, showing negative refractive index in the visible regime (around yellow-light wavelengths). The multi-layer- system retrieval was utilized to extract the effective refractive index of the metamaterial. It was also intuitively characterized through our wedge setup to demonstrate corresponding phenomena of refraction.