Ultra-light \AA-scale Optimal Optical Reflectors

TL;DR

This paper demonstrates that graphene-hexagonal boron nitride heterostructures can serve as ultra-light, highly reflective optical components in the mid-infrared range, surpassing metals in performance and tunability.

Contribution

It introduces a novel class of aa-scale graphene-based metamaterials with exceptional reflectivity and tunability for mid-IR applications, outperforming traditional noble metals.

Findings

Reflectivities exceeding 99.7% at wavelengths >10bcm

Greater plasmonic mode confinement and quality factors than noble metals

Potential for actively tunable optical devices via doping

Abstract

High-reflectance in many state-of-the-art optical devices is achieved with noble metals. However, metals are limited by losses, and for certain applications, by their high mass density. Using a combination of ab initio and optical transfer matrix calculations, we evaluate the behavior of graphene-based \AA-scale metamaterials and find that they could act as nearly-perfect reflectors in the mid-long wave infrared (IR) range. The low density of states for electron-phonon scattering and interband excitations leads to unprecedented optical properties for graphene heterostructures, especially alternating atomic layers of graphene and hexagonal boron nitride, at wavelengths greater than $10~\mu$m. At these wavelengths, these materials exhibit reflectivities exceeding 99.7% at a fraction of the weight of noble metals, as well as plasmonic mode confinement and quality factors that are greater by an order of magnitude compared to noble metals. These findings hold promise for ultra-compact optical components and waveguides for mid-IR applications. Moreover, unlike metals, the photonic properties of these heterostructures could be actively tuned via chemical and/or electrostatic doping, providing exciting possibilities for tunable devices.