Contrast of 83% in reflection measurements on a single quantum dot

Pia Lochner,Martin Geller,Rüdiger Schott,Axel Lorke,Andreas D Wieck,Annika Kurzmann,Arne Ludwig

doi:10.1038/s41598-019-45259-z

Pia Lochner, Martin Geller + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-45259-z

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Abstract

We report on a high optical contrast between the photon emission from a single self-assembled quantum dot (QD) and the back-scattered excitation laser light. In an optimized semiconductor heterostructure with an epitaxially grown gate, an optically-matched layer structure and a distributed Bragg reflector, a record value of 83% is obtained; with tilted laser excitation even 885%. This enables measurements on a single dot without lock-in technique or suppression of the laser background by cross-polarization. These findings open up the possibility to perform simultaneously time-resolved and polarization-dependent resonant optical spectroscopy on a single quantum dot.

Highlights

We report on a high optical contrast between the photon emission from a single self-assembled quantum dot (QD) and the back-scattered excitation laser light
A usual molecular beam epitaxy (MBE) grown sample for resonant optical measurements contains a layer of self-assembled QDs in a diode-like (Al)GaAs heterostructure, where the dots are separated from a n-doped back contact by tunneling barrier[4]
As the interaction between the QD and the light field is squeezed into c as fitting parameter, we can already conclude here, that this interaction seems to be strongly enhanced in our sample structure, showing such a high value for the fit parameter

Summary

Introduction

We report on a high optical contrast between the photon emission from a single self-assembled quantum dot (QD) and the back-scattered excitation laser light. In an optimized semiconductor heterostructure with an epitaxially grown gate, an optically-matched layer structure and a distributed Bragg reflector, a record value of 83% is obtained; with tilted laser excitation even 885%. This enables measurements on a single dot without lock-in technique or suppression of the laser background by cross-polarization. Resonance fluorescence is a widely used possibility to address resonantly the exciton transition in a single QD3–5 and generate single, indistinguishable photons[6,7,8] This requires the suppression of the laser background by several orders of magnitude, e.g., by a dark-field technique based on cross-polarization[3,9,10] or perpendicular QD excitation and photon detection[11,12].

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