Combined metallic nano-rings and solid-immersion lenses for bright emission from single InAs/GaAs quantum dots

TL;DR

This paper demonstrates a combined nano-ring and super-solid immersion lens to significantly boost photon extraction efficiency from single InAs/GaAs quantum dots, enabling near-million photon counts per second for quantum photonic applications.

Contribution

It introduces a novel integrated device combining metallic nano-rings and super-solid immersion lenses to enhance light extraction from quantum emitters.

Findings

Photon fluxes approaching 1 million counts/sec achieved.

Extraction efficiency increased by up to a factor of 200.

Broadband enhancement applicable to various solid-state emitters.

Abstract

Solid-state single-photon emitters are key components for integrated quantum photonic devices. However, they can suffer from poor extraction efficiencies, caused by the large refractive index contrast between the bulk material they are embedded in and air: this results in a small fraction (that can be as low as <1%) of the emitted photons reaching free-space collection optics. To overcome this issue, we present a device that combines a metallic nano-ring, positioned on the sample surface and centered around the emitter, and an epoxy-based super-solid immersion lens, deterministically deposited above the ring devices. We show that the combined broadband lensing effect of the nano-ring and of the super-solid immersion lens significantly increases the extraction of light emitted by single InAs/GaAs quantum dots into free space: we observe enhancements in the emitted intensity by the nano-ring of up to a factor 20 and by the super-solid immersion lens of up to a factor 10. Such cumulative enhancements allow us to measure photon fluxes approaching 1 million counts per second, from a single InAs/GaAs quantum dot in bulk. The combined broad-band enhancement in the extraction of light can be implemented with any kind of classical and quantum solid-state emitter and opens the path to the realisation of scalable bright devices. The same approach can also be implemented to improve the absorption of light, for instance for small-area broadband photo-detectors.