ISBN 9783843955911

978-3-8439-5591-1, Reihe Physik

Florian Hornung
Photonic integrated circuits using III-V semiconductor quantum dots as non-classical light sources

278 Seiten, Dissertation Universität Stuttgart (2024), Softcover, A5

Zusammenfassung / Abstract

Several quantum technologies, such as photonic quantum computing, simulation, and metrology, strongly benefit from scalable photonic integrated circuits (PICs). A crucial effect in these technologies is two-photon interference (TPI) from indistinguishable single photons at a beamsplitter. Essential components to realize this effect in a PIC include efficient photon sources, single-mode waveguides, and on-chip beamsplitters. Semiconductor quantum dots (QDs) are promising emitters for such applications.

This work investigates two monolithic platforms for integrating QDs into PICs to enable on-chip TPI. The first platform incorporates self-assembled In(Ga)As QDs into GaAs/AlGaAs waveguides. Two on-chip beamsplitter designs are compared, and hafnium dioxide crystallization is introduced for spectral tuning between QDs. A statistical analysis of emission properties is performed to discuss their impact on the expected TPI visibility, before the experimental realization is tested with a candidate pair. Integrated Bragg cavities are studied to enhance efficiency, and strain tuning via planar piezo and laser-cut piezo structures is explored to align QD and cavity resonance for future TPI.

The second platform integrates GaAs QDs grown by droplet etching epitaxy (DEE) into PICs. These QDs have been used to demonstrate record values in single-photon purity and indistinguishability in recent years. The structure consists of AlGaAs layers enabling DEE and providing waveguide contrast. This work presents the first successful integration of DEE GaAs QDs into single-mode waveguides with on-chip beamsplitters. Key studies include resonant excitation and emitter characterization, yielding high photon indistinguishability. These advancements mark a significant step toward achieving on-chip TPI and advancing quantum technologies.