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Chapter and Conference Paper
Change in Microstructure and Magnetic Properties of Transition Metal Nitride Thin Films by Substrate Temperature
The magnetic and mechanical properties of transition metal nitrides can be altered in many ways by their composition and microstructure, thus giving them excellent usability for spintronics and corrosion resis...
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Article
Photon Echo from an Ensemble of (In,Ga)As Quantum Dots
Photon echo from trions and excitons in (In,Ga)As/GaAs quantum dots was studied theoretically and experimentally. Theoretical analysis allowed us to distinguish between photon echo signals from excitons and tr...
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Article
Open AccessPrototype of a bistable polariton field-effect transistor switch
Microcavity exciton polaritons are promising candidates to build a new generation of highly nonlinear and integrated optoelectronic devices. Such devices range from novel coherent light emitters to reconfigura...
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Article
Open AccessCarrier transfer between confined and localized states in type II InAs/GaAsSb quantum wells
Temperature-resolved photoluminescence studies were performed on tensely-strained AlSb/InAs/GaAsSb W-shaped type II quantum wells. They revealed two emission bands: one at lower energy of localized origin resu...
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Article
Open AccessVisualising Berry phase and diabolical points in a quantum exciton-polariton billiard
Diabolical points (spectral degeneracies) can naturally occur in spectra of two-dimensional quantum systems and classical wave resonators due to simple symmetries. Geometric Berry phase is associated with thes...
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Article
Open AccessPhotoluminescence quenching mechanisms in type II InAs/GaInSb QWs on InAs substrates
Optical properties of AlSb/InAs/GaInSb/InAs/AlSb quantum wells (QWs) grown on an InAs substrate were investigated from the point of view of room temperature emission in the mid- and long-wavelength infrared ra...
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Article
Multi-wave coherent control of a solid-state single emitter
The coherent control of bright excitons in InAs quantum dots is demonstrated by combining heterodyne spectral interferometry with nonlinear multi-wave mixing. The spectro-temporal shape of the coherent emissio...
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Article
Quantum dot micropillar cavities with quality factors exceeding 250,000
We report on the spectroscopic investigation of quantum dot micropillar cavities with unprecedented quality factors. We observe a pronounced dependency of the quality factor on the measurement scheme and find...
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Article
Observation of non-Hermitian degeneracies in a chaotic exciton-polariton billiard
In non-Hermitian systems, spectral degeneracies can arise that can cause unusual, counter-intuitive effects; here exciton-polaritons—hybrid light–matter particles—within a semiconductor microcavity are found t...
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Article
Dynamics of spatial coherence and momentum distribution of polaritons in a semiconductor microcavity under conditions of Bose-Einstein condensation
The dynamics of spatial coherence and momentum distribution of polaritons in the regime of Bose-Einstein condensation in a GaAs microcavity with embedded quantum wells under nonresonant excitation with picosec...
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Chapter
Single Semiconductor Quantum Dots in Microcavities: Bright Sources of Indistinguishable Photons
In this chapter we will discuss the technology and experimental techniques to realize quantum dot (QD) single photon sources combining high outcoupling efficiencies and highest degrees of photon indistinguisha...
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Article
Open AccessLasing from active optomechanical resonators
Planar microcavities with distributed Bragg reflectors (DBRs) host, besides confined optical modes, also mechanical resonances due to stop bands in the phonon dispersion relation of the DBRs. These resonances ...
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Article
Manipulating the self assembly of colloids in electric fields
During the last decade the focus in colloid science on self-assembly has moved from mostly spherical particles and interaction potentials to more and more complex particle shapes, interactions and conditions. ...
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Article
Open AccessMicrocavity controlled coupling of excitonic qubits
Controlled non-local energy and coherence transfer enables light harvesting in photosynthesis and non-local logical operations in quantum computing. This process is intuitively pictured by a pair of mechanical...
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Article
Above GaSb barrier in type II quantum well structures for mid-infrared emission detected by Fourier-transformed modulated reflectivity
Modulation spectroscopy in its Fourier-transformed mode has been employed to investigate the optical properties of broken gap ‘W’-shaped GaSb/AlSb/InAs/InGaSb/InAs/AlSb/GaSb quantum well structures designed to...
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Article
InGaN-Channel FETs - Growth, Technology and Characteristics
Making use of the polar nature of III-nitride heterostructures, a new FET device concept is proposed. The structure contains an InGaN QW channel sandwiched in between two GaN barrier layers. The charge inthis ...
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Article
GaN Homoepitaxy for Device Applications
Epitaxial growth on GaN single bulk crystals sets new standards in GaN material quality. The outstanding properties provide new insights into fundamental material parameters (e.g. lattice constants, exciton bi...
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Article
Invasive pulmonale Aspergillose
Die invasive pulmonale Aspergillose (IPA) ist eine lebensgefährliche Erkrankung, die vorwiegend bei Patienten mit gestörter Immunabwehr, z. B. im Rahmen einer akuten Leukämie, auftritt. Das vorliegende Fallbei...
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Article
Optimization of the wallplug-efficiency of laser diodes by an electro-optical-thermal black-box model
A black-box model for the optimization of the wallplug efficiency by choosing appropriate “external” parameters of an edge emitting laser – resonator length, operating current – is presented and applied to a h...
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Chapter
Strains and Stresses in GaN Heteroepitaxy -- Sources and Control
We present a study of the sources of strain in GaN heteroepitaxy by in- and ex-situ measurement techniques. With an in-situ curvature measurement technique the strain development can be directly correla...
