Radiative Emission Enhancement Using Nano-antennas Made of Hyperbolic Metamaterial Resonators

TL;DR

This paper demonstrates that hyperbolic metamaterial resonators can significantly enhance free-space radiative emission from quantum emitters, with about 100-fold increase at 660 nm, and explores how array configurations affect this enhancement.

Contribution

It introduces a numerical analysis of hyperbolic metamaterial nano-antennas for radiative emission enhancement, focusing on free-space coupling and array effects, which was not extensively studied before.

Findings

Approximately 100 times emission enhancement at 660 nm.

Enhancement depends on dipole orientation and emitter position.

Array of resonators retains most of the single-resonator enhancement.

Abstract

A hyperbolic metamaterial (HM) resonator is analyzed as a nano-antenna for enhancing the radiative emission of quantum emitters in its vicinity. It has been shown that the spontaneous emission rate by an emitter near a hyperbolic metamaterial substrate is enhanced dramatically due to very large density of states. However, enhanced coupling to the free-space, which is central to applications such as solid-state lighting, has not been investigated significantly. Here, we numerically demonstrate approximately 100 times enhancement of the free-space radiative emission at 660 nm wavelength by utilizing a cylindrical HM resonator with a radius of 54 nm and a height of 80 nm on top of an opaque silver-cladded substrate. We also show how the free-space radiation enhancement factor depends on the dipole orientation and the location of the emitter near the subwavelength resonator. Furthermore, we calculate that an array of HM resonators with subwavelength spacings can maintain most of the enhancement effect of a single resonator.