ISBN 9783843948333

978-3-8439-4833-3, Reihe Physik

Stefan Hepp
Quantum dot single-photon sources based on waveguide Bragg grating cavities for integrated quantum photonics

215 Seiten, Dissertation Universität Stuttgart (2021), Softcover, A5

Zusammenfassung / Abstract

Photonic integrated circuits are a highly attractive platform for the scalable realization of modern quantum photonic devices on a small footprint. This makes the monolithic combination of certain key functionalities that enable the efficient generation, guiding, manipulation and detection of single photons on a photonic chip crucial. Among different material platforms being investigated, are gallium arsenide (GaAs) based photonic integrated circuits an appealing future platform for the realization of this goal. One reason is the straightforward combination with self-assembled quantum dots (QDs), that have proven to be an outstanding on-demand source of single photons with a simultaneous high purity and indistinguishability.

The work at hand targets the development of monolithic functional single-photon devices for QD-based photonic integrated circuits realized on a GaAs ridge waveguide platform. Here, high-Q cavities were directly integrated within the photonic circuit, dramatically increasing the inherently limited QD coupling efficiency via cavity quantum electrodynamic effects that further enabled the enhanced light-matter interaction between the emitter and the resonator.

The first part of this thesis includes a comprehensive numerical investigation of the microcavities which is followed by an experimental study demonstrating the Purcell enhanced and on-demand generation of single photons from a QD in a cavity-coupled waveguide circuit with high efficiency.

Secondly, a post-growth in-situ tuning method is realized for the spectral matching of the QD emission and the cavity resonance. Therefore, a hybrid piezoelectric-semiconductor integration scheme was realized which allowed for the strain-induced fine tuning of the emitter emission wavelength. This crucial key functionality paved the way for the controlled QD-cavity coupling and the optimal exploitation of the Purcell effect in the here presented on-chip single-photon devices.