Durch fortschreitende Entwicklung im Bereich der Starkfeldphysik und der Lasertechnologie in den letzten Jahrzehnten kann die Dynamik von Elektronen induziert durch Laserpulse verschiedener Wellenlängen, komplexen Polarisationseigenschaften, ultrakurzer Dauer und großer Intensität in hohem Umfang kontrolliert und ausgenutzt werden. In dieser Arbeit werden maßgeschneiderte Laserpulse angewendet, um verschiedene Aspekte der atomaren Licht-Materie-Wechselwirkung im Starkfeldbereich zu untersuchen. Im ersten Teil der Arbeit wird insbesondere die Erzeugung von hohen Harmonischen erforscht, die durch zirkular polarisierte Laserfelder erzeugt werden, wobei das maßgeschneiderte Feld aus einem zirkular polarisierten Infrarotpuls und seiner zweiten Harmonischen mit entgegengesetzter zirkularer Polarisation besteht. Die Polarisation von zirkularen hohen Harmonischen wird mittels spektral aufgelöster Polarimetrie unter Verwendung eines selbst entwickelten Polarimeters gemessen und ein Verfahren vorgestellt, mit dem der Stokes-Vektor der hoch zirkular polarisierten Harmonischen vollständig rekonstruiert werden kann. Darüber hinaus wird zum ersten Mal gezeigt, dass das bizirkulare Schema auch auf erzeugende Laserpulse weniger Zyklen erweiterbar ist. Der zweite Teil der Arbeit konzentriert sich auf die Starkfeldanregung eines Atoms durch einen intensiven Laserpuls. Da die ponderomotorische Verschiebung eines ausreichend intensiven Laserpulses eine resonante Anregung eines durch den Stark-Effekt verschobenen Atomzustands sowohl an der Vorder- als auch an der Rückflanke des Pulses bewirkt, diktiert die fundamentale Quantenmechanik, dass die an diesen Instanzen angeregten Elektronenwellenpakete interferieren müssen. Durch Variation der Verzögerung zwischen den Instanzen kann ein Interferenzmuster beobachtet werden, das als Stückelberg-Oszillationen bekannt ist und wertvolle Informationen über die Ionisierungsrate stark angeregter atomarer Zustände enthält. / As our fundamental understanding of strong-field physics and laser technology have matured in the last few decades, we are able to control and exploit electron dynamics using laser pulses of multiple colors, complex polarization properties, ultrashort duration and high intensity. This thesis makes use of such tailored laser fields to study different aspects of atomic light-matter interaction within the strong-field regime. Particularly, the first part of the thesis explores high-harmonic generation driven by circularly polarized driving fields, where the tailored field is composed of a circularly polarized infrared pulse and its second harmonic with opposite circular polarization, often denoted as 'bicircular' driving field. We measure the polarization of bicircularly generated harmonics by means of spectrally resolved polarimetry using a self-developed polarimeter and present a scheme, which allows to fully reconstruct the Stokes vector of the highly circularly polarized harmonics. We further demonstrate for the first time, that the bicircular scheme is also applicable within the regime of few-cycle driving pulses. Applying driving fields containing only a few carrier oscillations, we present the generation of a broadband harmonic spectrum with highly elliptically polarized spectral content, supporting the generation of an isolated attosecond pulse. The second part of the thesis focuses on strong-field excitation of an atom by an intense laser pulse. When the ponderomotive shift of a sufficiently intense laser pulse induces resonant excitation of a Stark-shifted atomic state at both the leading and trailing edge of the pulse, fundamental quantum mechanics dictates that the electron wave packets excited at these instances must interfere. By varying the delay between the instances, we observe the interference pattern known as Stückelberg oscillations which holds valuable information about the ionization rate of strongly driven atomic states.

Many textile products are using materials with higher thickness like foams, spacer fabrics and nonwoven materials in order to provide comfortable softness of the contact surface to the body. Such materials are often joint to another external layer who have to provide optical and mechanical stability of the system, and are joined together into a 3-dimensional geometry. This paper analyses some steps of joining such materials by sewing. The forces in the sewing threads are analyzed analytically. A numerical model based on finite element method (FEM) is implemented in LS-Dyna and the process of compaction of the sewing line, based on the thread force is simulated. The thread force propagation is numerically analyzed in the time, at different friction coefficients and for different foam stiffness. All simulations demonstrate logical results and can be used as a fundament for more complex investigations and optimizations of such products.

In den letzten Jahrzehnten haben Tischlaserquellen eine bemerkenswerte Entwicklung durchlaufen. Sie sind nun in der Lage, maßgeschneiderte ultrakurze Mehrfarben-Laserpulse zu erzeugen, die es ermöglichen, die elektronische Dynamik in Materialien auf ihrer natürlichen Zeitskala von Attosekunden zu untersuchen. In dieser Arbeit werden verschiedene Kombinationen von elektrischen Feldern genutzt, von extrem-ultravioletten (XUV) bis nahinfraroten Wellenlängen, um komplexe Elektronendynamiken in Atomen und chiralen Medien zu erforschen, zu rekonstruieren und zu kontrollieren. Dabei werden grundlegende Konzepte der Licht-Materie-Wechselwirkung eingeführt, einschließlich starker Feldprozesse, die im Kern der Attosekundenspektroskopie liegen. Ein Schwerpunkt liegt auf der Nutzung eines XUV-Pulses in Kombination mit einem nahinfraroten Puls, um den Bevölkerungstransfer zu hohen Drehimpulszuständen in Heliumatomen zu untersuchen. Durch Manipulation der Laserparameter wird die Rolle des AC Stark-Effekts von gebundenen Zuständen in der beobachteten Dynamik identifiziert. Weitere Untersuchungen umfassen die Verwendung eines bicirculären elektrischen Feldes zur Induktion von HHG in Argon, wobei Anzeichen einer starken Feldfangung von Elektronen in angeregten Zuständen im HHG-Spektrum entdeckt werden. Die Arbeit zeigt die entscheidende Rolle angeregter Zustände in der HHG auf. Zusätzlich wird die Anwendung synthetischer chiraler Felder erforscht, um Chiralität auf achirale Objekte wie Atome zu übertragen, und es wird eine Verbindung zwischen synthetischen chiralen Feldern und strukturiertem Licht hergestellt. / In recent decades table-top laser sources have undergone remarkable development and are now capable of generating tailored ultrashort multicolor laser pulses, enabling the study of electronic dynamics in materials on their natural timescale of the attoseconds. In this thesis work various combinations of electric fields spanning from extreme-ultraviolet (XUV) to near-infrared wavelengths are used to investigate, reconstruct and control complex electron dynamics in atoms and chiral media. The initial chapter of this thesis introduces the fundamental concepts underlying light-matter interaction, including strong field processes which lie at the core of attosecond spectroscopy. The second chapter focuses on the utilization of an XUV pulse combined with a near-infrared pulse to study population transfer to high angular momentum states in helium atoms. By manipulating laser parameters, the study identifies the significant role played by the AC Stark shift of bound states in the observed dynamics. In the third chapter a bicircular electric field is employed to induce HHG in argon. Changing the timedelay between the two frequencies, indications of strong field trapping of electrons in excited states are uncovered within the HHG spectrum, confirming the existence of long-lived trajectories lasting multiple optical cycles. The study conclusively demonstrates the crucial role of excited states in HHG. The fourth chapter explores the application of synthetic chiral fields—whose polarization traces a chiral curve over the optical cycle—to imprint chirality on achiral objects such as atoms, both in the low- and strong-field regime. Moreover, the thesis establishes a connection between synthetic chiral fields and structured light, introducing chiral vortex beams with azimuthally varying handedness.

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For ultra-high speed communication systems at high center frequencies above 100 GHz, we propose a disruptive change in system architecture to address major issues regarding amplifier chains with a large number of amplifier stages. They cause a high noise figure and high power consumption when operating close to the frequency limits of the underlying semiconductor technologies. Instead of scaling a classic homodyne transceiver system, we employ repeated amplification in single-stage amplifiers through positive feedback as well as synthesizer-free self-mixing demodulation at the receiver to simplify the system architecture notably. Since the amplitude and phase information for the emerging oscillation is defined by the input signal and the oscillator is only turned on for a very short time, it can be left unstabilized and thus come without a PLL. As soon as gain is no longer the most prominent issue, relaxed requirements for all the other major components allow reconsidering their implementation concepts to achieve further improvements compared to classic systems. This paper provides the first comprehensive overview of all major design aspects that need to be addressed upon realizing a SPARS-based transceiver. At system level, we show how to achieve high data rates and a noise performance comparable to classic systems, backed by scaled demonstrator experiments. Regarding the transmitter, design considerations for efficient quadrature modulation are discussed. For the frontend components that replace PA and LNA amplifier chains, implementation techniques for regenerative sampling circuits based on super-regenerative oscillators are presented. Finally, an analog-to-digital converter with outstanding performance and complete interfaces both to the analog baseband as well as to the digital side completes the set of building blocks for efficient ultra-high speed communication.

In this paper, electrification of hydraulic systems is proposed using high-efficiency permanent magnet (PM) motors and wide bandgap power electronic drives. Direct driven hydraulics (DDH) is selected because of its higher efficiency compared to other conventional technologies such as valve-controlled systems. The DDH is directly driven by a servomotor. The ratings and design guidelines for a servomotor used in DDH applications are provided in this paper. Specifically, a surface permanent magnet synchronous machine (SPMSM) is designed. Finally, a state-of-the-art inverter using silicon carbide wide bandgap devices are designed for high performance operation.

This thesis develops a computationally efficient way of employing Gaussian wave packets to study laser-induced electron dynamics in atomic and molecular systems by directly solving the time-dependent Schrödinger equation (TDSE). First, we investigate charge migration (treating the nuclei classically), high-order harmonic generation (HHG), and single-isolated attosecond pulse generation in the Hydrogen molecular ion subjected to intense laser fields in a different range of frequencies with a basis of static coherent states (SCS). Then, seeking for a smarter way of constructing and guiding a minimal set of time-dependent basis functions, we introduce a fast and accurate approach for optimizing s-type Gaussian type orbitals (GTOs) and apply it to calculate electronic states of different 1D and 3D time-independent systems. Finally, we apply our optimization approach to time-dependent problems. With our approach we obtain excellent agreement with the exact results for HHG spectra of the 1D Hydrogen atom and molecular ion exposed to intense laser fields, which is not possible even with a much larger basis of static s-type GTOs. / Diese Arbeit sucht nach einem computereffizienten Ansatz für die Verwendung von Gaußschen Wellenpaketen zur Untersuchung der Quantenelektronendynamik in atomaren und molekularen laserinduzierten Systemen durch direkte Lösung der zeitabhängigen Schrödingergleichung (TDSE). Beginnend mit statischen kohärenten Zuständen (SCS) untersuchen wir die Ladungsmigration (wobei wir die Kerne klassisch behandeln), die Erzeugung von Oberwellen höherer Ordnung (HHG) und die Erzeugung von isolierten Attosekundenimpulsen im 3D-Wasserstoffmolekül-Ion \ih, das intensiven Laserfeldern in einem unterschiedlichen Frequenzbereich ausgesetzt ist. Auf der Suche nach einer intelligenteren Methode zur Konstruktion und Führung eines minimalen Satzes von Basisfunktionen stellen wir einen schnellen und genauen Ansatz zur Optimierung von Gauß-Orbitalen (GTOs) vom s-Typ vor und wenden ihn erfolgreich zur Berechnung gewünschter elektronischer Zustände verschiedener 1D- und 3D-Quantensysteme an. Letztendlich erweitern wir unseren Optimierungsansatz auf zeitabhängige Szenarien. Wir demonstrieren, wie diese Methode eine ausgezeichnete Übereinstimmung mit den exakten Ergebnissen in den HHG-Spektren des 1D-Wasserstoffatoms und des 1D-\ih, die intensiven Laserfeldern ausgesetzt sind, erzielt, wo die nicht optimierten s-Typ GTOs nicht übereinstimmen, selbst nach den ersten paar Harmonien im Plateaubereich.

One of the major obstacles for designing solutions against the imminent climate crisis is the scarcity of high spatio-temporal resolution model projections for variables such as precipitation. This kind of information is crucial for impact studies in fields like hydrology, agronomy, ecology, and risk management. The currently highest spatial resolution datasets on a daily scale for projected conditions fail to represent complex local variability. We used deep-learning-based statistical downscaling methods to obtain daily 1 km resolution gridded data for precipitation in the Eastern Ore Mountains in Saxony, Germany. We built upon the well-established climate4R framework, while adding modifications to its base-code, and introducing skip connections-based deep learning architectures, such as U-Net and U-Net++. We also aimed to address the known general reproducibility issues by creating a containerized environment with multi-GPU (graphic processing unit) and TensorFlow's deterministic operations support. The perfect prognosis approach was applied using the ERA5 reanalysis and the ReKIS (Regional Climate Information System for Saxony, Saxony-Anhalt, and Thuringia) dataset. The results were validated with the robust VALUE framework. The introduced architectures show a clear performance improvement when compared to previous statistical downscaling benchmarks. The best performing architecture had a small increase in total number of parameters, in contrast with the benchmark, and a training time of less than 6 min with one NVIDIA A-100 GPU. Characteristics of the deep learning models configurations that promote their suitability for this specific task were identified, tested, and argued. Full model repeatability was achieved employing the same physical GPU, which is key to build trust in deep learning applications. The EURO-CORDEX dataset is meant to be coupled with the trained models to generate a high-resolution ensemble, which can serve as input to multi-purpose impact models.

Solution-processed lead sulfide quantum dots (PbS QDs) are an excellent candidate for photodetector applications because they exhibit broadband absorption, a wide range of tuneable bandgaps, high stability in air, and mechanical flexibility. However, a crucial criterion for the fabrication of high-performance photodetectors is the selection of the ligands, which can facilitate charge carrier transport between the PbS QDs and passivate the surface defects. In this work, the authors have studied the effect of traps on the performance of PbS QD photodetectors that are fabricated using different types of ligands, using intensity-dependent photoresponse dynamics. The best devices with lead halide ligands show a dark current density of 5 × 10−9 A cm−2 at −0.2 V, which is one of the lowest values reported thus far for solution-processed PbS QD-based photodetectors. Moreover, these devices show a high linear dynamic range (≈90 dB) and high detectivity (>1013 Jones), in addition to an f-3 dB of greater than 100 kHz without the application of an external voltage bias at a wavelength of 784 nm. These results suggest that with an appropriate selection of ligands, solution-processed photodetectors with a lower density of traps and a better device performance can be fabricated.

Optimizing a modulator driver for linear and high-speed operation, while simultaneously achieving a high output voltage swing is very challenging. This paper investigates the design of a highlylinear, high-bandwidth yet power-efficient Mach-Zehnder modulator driver based on the breakdown voltage doubler concept, which overcomes the transistors' physical limitations and enables output voltage swings twice as high as conventional differential pair amplifiers can provide. The low-power design was enabled by the use of an open-collector topology for the output stage as well as by employing resistors instead of current mirrors in order to provide the bias currents for the emitter-follower (EF) stages. We show that by means of this EF implementation approach, the power consumption can be reduced by 19% without sacrificing the circuit's bandwidth and linearity. The driver achieves peak-to-peak differential output voltage swings above 6.5 Vpp,d and consumes 670mWof DC power, being one of the most power-efficient drivers in the literature. The 3-dB bandwidth is 61.2 GHz and the total harmonic distortion is 1%, measured at 1 GHz and for the output swing of 6.5 Vpp,d. To the best of the authors' knowledge, these are the highest linearity and output voltage swing reported in the literature for modulator drivers with bandwidths above 40 GHz.