A circular dielectric grating for vertical extraction of single quantum dot emission
Marcelo I. Davanco, Matthew T. Rakher, Dieter Schuh, Antonio Badolato, Kartik A. Srinivasan
We demonstrate a suspended circular grating composed of partially etched annular trenches in a thin GaAs membrane, designed for e±cient and moderately broadband ( approx. 5 nm) extraction of emission from single InAs quantum dots. Simulations indicate that a single dipole embedded in the center of the nanostructure radiates upwards into free space with a nearly Gaussian far-feld, allowing a collection e±ciency > 80% with a high numerical aperture (NA=0.7) optic, and with 12 times Purcell radiative rate enhancement. Fabricated devices exhibit a 10 % photon collection effciency with a NA=0.42 objective, a 20 times improvement over quantum dots in unpatterned GaAs. A fourfold reduction in quantum dot exciton lifetime is observed, suggesting moderate Purcell enhancement.