Monolithic Polarizing Circular Dielectric Gratings on Bulk Substrates for Improved Photon Collection from InAs Quantum Dots

TL;DR

This paper presents a novel monolithic circular dielectric grating design on bulk substrates that significantly enhances photon collection from InAs quantum dots, enabling better integration with quantum systems and broadening application potential.

Contribution

It introduces a new monolithic dielectric grating structure with a two-tiered DBR for improved photon collection from quantum dots on bulk substrates, unlike previous suspended or bonded structures.

Findings

Enhanced photon collection efficiency demonstrated

Polarized quantum dot luminescence achieved

Designs compatible with bulk substrate integration

Abstract

III-V semiconductor quantum dots (QDs) are near-ideal and versatile single-photon sources. Because of the capacity for monolithic integration with photonic structures as well as optoelectronic and optomechanical systems, they are proving useful in an increasingly broad application space. Here, we develop monolithic circular dielectric gratings on bulk substrates -- as opposed to suspended or wafer-bonded substrates -- for greatly improved photon collection from InAs quantum dots. The structures utilize a unique two-tiered distributed Bragg reflector (DBR) structure for vertical electric field confinement over a broad angular range. Opposing ``openings" in the cavities induce strongly polarized QD luminescence without harming collection efficiencies. We describe how measured enhancements depend critically on the choice of collection optics. This is important to consider when evaluating the performance of any photonic structure that concentrates farfield emission intensity. Our cavity designs are useful for integrating QDs with other quantum systems that require bulk substrates, such as surface acoustic wave phonons.