Exciton Fine Structure in InAs Quantum Dots with Cavity-Enhanced Emission at Telecommunication Wavelength and Grown on a GaAs (111) A Vicinal Substrate

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.