Fine structure splitting analysis of cavity-enhanced telecom-wavelength InAs quantum dots grown on a GaAs(111)A vicinal substrate

TL;DR

This paper reports on the growth and characterization of telecom-wavelength InAs quantum dots on a vicinal GaAs(111)A substrate, demonstrating enhanced photon extraction, reduced density, and insights into how substrate miscut affects exciton fine structure and polarization.

Contribution

It introduces a droplet epitaxy method for embedding InAs QDs in optical cavities on a vicinal substrate, analyzing the effects of miscut on optical properties and exciton fine structure.

Findings

Enhanced photon extraction efficiency compared to previous reports.

Reduced quantum dot density facilitating single spectral line isolation.

Substrate miscut influences exciton polarization and symmetry orientation.

Abstract

The effcient generation of entangled photons at telecom wavelength is crucial for the success of many quantum communication protocols and the development of fiber-based quantum networks. Entangled light can be generated by solid state quantum emitters with naturally low fine structure splitting, such as highly symmetric InAs quantum dots (QDs) grown on (111)-oriented surfaces. Incorporating this kind of QDs into optical cavities is critical to achieve sufficient signal intensitiesfor applications, but has so far shown major complications. In this work we present droplet epitaxy of telecom-wavelength InAs QDs within an optical cavity on a vicinal (2{\deg} miscut) GaAs(111)A substrate. We show a remarkable enhancement of the photon extraction efficiency compared to previous reports together with a reduction of the density that facilitates the isolation of single spectral lines. Moreover, we characterise the exciton fine structure splitting and employ numerical simulations under the framework of the empirical pseudopotential and configuration interaction methods to study the impact of the miscut on the optical properties of the QDs. We demonstrate that the presence of miscut steps influences the polarisation of the excitonic states and introduces a preferential orientation in the $C_{3v}$ symmetry of the surface.