Hyperbolic Metamaterial Nano-Resonators Make Poor Single Photon Sources

TL;DR

Hyperbolic metamaterial nano-resonators provide large Purcell enhancements but result in very low single photon output efficiency, making them unsuitable as single photon sources due to increased Ohmic quenching.

Contribution

This study reveals that hyperbolic metamaterial nano-resonators, despite high Purcell factors, are ineffective as single photon sources because of low output efficiency caused by Ohmic losses.

Findings

Purcell enhancements are nearly ten times larger than plasmonic resonators.

Single photon output $eta$-factors are around 10%, much lower than metallic resonators.

Low $eta$-factors are due to increased Ohmic quenching from redshifted resonances and stronger light confinement.

Abstract

We study the optical properties of quantum dipole emitters coupled to hyperbolic metamaterial nano-resonators using a semi-analytical quasinormal mode approach. We show that coupling to metamaterial nano-resonators can lead to significant Purcell enhancements that are nearly an order of magnitude larger than those of plasmonic resonators with comparable geometry. However, the associated single photon output $\beta$-factors are extremely low (around 10$\%$), far smaller than those of comparable sized metallic resonators (70$\%$). Using a quasinormal mode expansion of the photon Green function, we describe how the low $\beta$-factors are due to increased Ohmic quenching arising from redshifted resonances, larger quality factors, and stronger confinement of light within the metal. In contrast to current wisdom, these results suggest that hyperbolic metamaterial nano-structures make poor choices for single photon sources.