A circular dielectric grating for vertical extraction of single quantum dot emission

TL;DR

This paper presents a nanostructure that enhances the vertical extraction efficiency of single quantum dot emission, achieving significant improvements in photon collection and radiative rate, with potential applications in quantum photonics.

Contribution

The study introduces a novel circular dielectric grating design that significantly improves emission extraction and Purcell enhancement for single quantum dots.

Findings

Over 80% collection efficiency with high NA optics in simulations

Approximately 10% photon collection efficiency in fabricated devices

Fourfold reduction in exciton lifetime indicating Purcell enhancement

Abstract

We demonstrate a nanostructure composed of partially etched annular trenches in a suspended GaAs membrane, designed for efficient and moderately broadband (approx. 5 nm) emission extraction from single InAs quantum dots. Simulations indicate that a dipole embedded in the nanostructure center radiates upwards into free space with a nearly Gaussian far-field, allowing a collection efficiency > 80 % with a high numerical aperture (NA=0.7) optic, and with 12X Purcell radiative rate enhancement. Fabricated devices exhibit an approx. 10 % photon collection efficiency with a NA=0.42 objective, a 20X improvement over quantum dots in unpatterned GaAs. A fourfold exciton lifetime reduction indicates moderate Purcell enhancement.