The development of the field of the science of ultra-cold matter has opened some exciting possibilities in exploring the quantum-mechanical processes which dominate matter interactions at the sub-microscopic scale. Although methods of cooling atoms are well established, molecular cooling is made difficult by molecules’ additional vibrational and rotational degrees of freedom. It was the goal of the research in this work to approach molecular cooling indirectly, by using broadband shaped-pulse photoassociation for the generation of tightly bound ultracold Rb₂ molecules. The experiments towards this goal conducted by our group included a pumpdecay experiment to observe the generation of ground state singlet or triplet molecules. However, attempts to observe an increase in ground state population have been unsuccessful. A pump-probe study of wavepacket dynamics in the 5s+5p electronic state was conducted in order to determine the appropriate timing for the application of an additional pulse to dump population into the ground state. Although the attempt to observe wavepacket oscillations has been unsuccessful, pump-probe studies have yielded the observation of loosely bound excited state molecules as a result of the photoassociation pulse. These results are promising as a first stage in a fully coherent pump-dump approach to stabilisation into the lowest vibrational ground state. This thesis will provide an introduction and overview to the concerns involved in addressing the problem of molecular cooling and generation. Experimental techniques will be discussed including pulsed laser systems, optical parametric amplifi- cation, and the presentation of an original design for pulse shaping with an acoustooptic modulator. The emphasis of these discussions will be on the principles and operating procedures required for the use of these devices as home-built systems. The thesis will conclude with the results of pump-probe experiments utilising the pulse shaper as a spectral cutting device.

<p> The Selective Laser Melting (SLM) process is a manufacturing technique that facilitates the  production of metallic parts with complex geometries and reduces both materials waste and lead  time. The high tunability of the process parameters in SLM allows the design of the as-built part’s  characteristics, such as controlled microstructure formation, residual stresses, presence of pores,  and lack of fusion. The main parameter in the SLM process that influences these parts’  characteristics is the transient temperature field resulting from the laser-matter interaction.  Nanosecond pulsed lasers in SLM have the advantage of enabling rapid and localized heating and  cooling that make the formation of ultrafine grains possible. This work shows how different pulse  durations can change the near-surface microstructure and overall mechanical properties of metallic  parts. The nanosecond pulses can melt and resolidify aluminum parts’ near-surface region to form nanograined gradient structures with yield strengths as high as 250.8 MPa and indentation  strengths as high as 725 MPa, which are comparable to some steel's mechanical properties. Knowing that the nanosecond pulsed lasers cause microstructure refinement for high-purity metals,  the microstructure variations effects were also investigated for the cast iron alloy. Cast iron was  used alone and mixed with born or boron nitride powders to induce the precipitation of  strengthening phases only enabled under high cooling rates. Although producing parts with  superior mechanical properties and controlling the precipitation of strengthening phases, the SLM  process with nanosecond pulsed lasers is still accompanied by defects formation, mainly explained  by the large thermal gradients, keyhole effect, reduced melt pool depth, and rapid cooling rates.  Ideally, a smooth heating rate able to sinter powder grains, facilitating the heat flow through the  heat-affected zone, followed by a sharper heating rate that generates a fully molten region, but  minimizes ablation at the same time are targeted to reduce the porosity and lack of fusion. Then, a  sharp cooling rate that can increase the nucleation rate, consequently refining the final  microstructure is targeted in the production of strong materials in SLM with pulsed lasers. This  work is the pioneer in controlling the transient temperature field during the heating and cooling  stages in pulsed laser processing. The temperature field control capability by shaping a nanosecond  laser pulse in the time domain affecting defects formation, residual strains, and microstructure was  achieved, opening a wide research niche in the additive manufacturing field.  </p>

Der selektive Abtrag dünner Schichten findet für eine Vielzahl technischer Fertigungsverfahren Anwendung. Eine solche ist die Herstellung organischer Solarzellen, bei der mittels Laserabtrag die Funktionsschichten strukturiert werden, um eine monolithische Verschaltung zu erreichen. Aus Gründen der Lebensdauerverbesserung und zur Kostenreduktion gibt es Bestrebungen verschiedene Funktionalitäten wie Trägermaterial der Solarzellen und Wasserdampfbarriere zusammenzuführen. Im Rahmen der vorliegenden Dissertation wird der Abtrag von elektrisch leitfähigen, transpa-renten Schichten auf einer Wasserbarriereschicht aus Siliziumnitrid untersucht. Das Ziel ist ein vollständiger Abtrag der Elektrode zur elektrischen Separation, bei gleichzeitiger Erhaltung der Barriereeigenschaften der darunterliegenden Schicht. Die Untersuchungen zum Abtragsverhal-ten zeigen Schwankung in der Abtragsqualität der Elektrode. Mit Hilfe von Raman-Spektroskopie und der entwickelten Kontrastscan Methode kann gezeigt werden, dass diese Inhomogenität von Bereichen schwankender Brechzahl in der verwendeten Polyethylentereph-thalatfolie verursacht sind. Diese entstehen bei der Herstellung der Folie durch den Prozess des Verstreckens, um eine thermische Stabilisierung zu erreichen. Zur Entwicklung eines tieferen Verständnisses der Einflüsse auf die Abtragsqualität wird ein Simulationsmodell entwickelt. Es simuliert die optischen Gegebenheiten des gesamten Schichtverbunds und nutzt die ermittelten, lokal absorbierten Leistungen für die Berechnung der thermomechanischen Gegebenheiten in den Schichten nach dem Zwei-Temperatur-Modell. An Hand von Abtragsergebnissen zum Elektrodensystem Indiumzinnoxid (ITO) werden die Er-gebnisse des entwickelten Simulationsmodells mit dem bekannten Modell zur Absorption nach Lambert-Beer verglichen. Für ITO und einen weiteren Elektrodentyp, genannt Dielektrikum-Metall-Dielektrikum (DMD), wird die Übereinstimmung von Simulation und experimentellen Er-gebnissen zur Abtragsschwelle, der Breite des Elektrodenabtrags und zur Beeinflussung der Barriereschicht gegenübergestellt und diskutiert. Auf Basis der Erkenntnisse aus dem entwi-ckelten Simulationsmodell ist es gelungen prozesstechnische Anpassungen zu identifizieren, welche die Auswirkungen der lokalen Brechzahlschwankungen reduzieren. Durch Überführung der entwickelten Prozessabfolge auf eine Rolle-zu-Rolle-Bearbeitung wird schließlich die Ska-lierbarkeit nachgewiesen.:1 Einleitung 2 Stand der Technik 2.1 Herstellung organischer Solarzellen 2.2 Verkapselung organischer Elektronik 2.3 Flexible Barrieren 2.4 Laserprozessierung von funktionalen Schichten in der organischen Elektronik 2.5 Laserprozessierung auf flexiblen Barrieren 3 Motivation 4 Grundlagen 4.1 Physikalsiche Grundlagen 4.1.1 Verhalten elektromagnetischer Wellen an Grenzflächen 4.1.2 Lichtinterferenz und Transfermatrixmethode 4.1.3 Energieeintrag durch Absorption 4.1.4 Physikalische Effekte bei der Laser-Materie-Wechselwirkung 4.1.5 Das Zwei-Temperatur-Modell 4.1.6 Zusammenhang von Elektronendichte und Absorption 4.1.7 Generierung freier Ladungsträger 4.2 Materialgrundlagen 4.2.1 Herstellung von thermisch stabilisierten PET 4.2.2 Aufbau des verwendeten Barrieresystem 4.2.3 Herstellung und Eigenschaften der verwendeten Schichten 5 Experimentelle Arbeit und Simulation 5.1 Mess- und Analysemethoden 5.1.1 Spektrale Charakterisierung der Elektrodenschichten 5.1.2 Auflichtmikroskopie 5.1.3 Konfokalmikroskopie 5.1.4 Test auf Barriereintegrität 5.1.5 Messung des Isolationswiderstands 5.1.6 Parametertest an funktionellen Solarzellen 5.2 Laserbearbeitung 5.2.1 Laserauswahl 5.2.2 Strahlformung 5.2.3 Untersuchungen des Laserabtrags 5.2.4 Versuchsaufbau 5.3 Simulationsmodell 5.3.1 Simulationsmodell mit Absorption nach Lambert-Beer 5.3.2 Simulationsmodell mit Absorption durch Interferenzeffekten 6 Ergebnisse und Diskussion 6.1 Optische Eigenschaften der Schichten und Ermittlung von Kennwerten 6.2 Strahlcharakterisierung 6.3 Kontrastscan 6.4 Prozessentwicklung 6.4.1 Abtragsschwelle der Barriere 6.4.2 Laserabtrag der ITO-Elektrode 6.4.3 DMD-Bearbeitung 6.5 Rolle zu Rolle Prozessierung 6.5.1 Charakterisierung des Bandmaterials 6.5.2 Einzelpulsabtrag 6.5.3 Prozessfenster und Überführung auf die R2R-Laseranlage 7 Zusammenfassung 8 Literaturangaben 9 Anhang 9.1 Strahlvermessung zur Gaußsche Energieverteilung 9.2 Verwendung des VORTEX doE – Justage und resultierende Energieverteilung 9.3 Generierung einer TopHat Verteilung mit dem FBS DOE 9.4 ITO Abtrag mit dem Vortex-DOE 9.5 Prozessieren der DMD Varianten mit Alternative Energieverteilungen 9.6 Abtragsschwellen für Intensitäten 9.7 Weitere elektrische Ergebnisse

Le travail présenté dans cette thèse porte sur l’élaboration de couches minces des biomatériaux biomimétiques nanostructurées par des techniques lasers pulsés et leur évaluation de point de vue physico-chimique et biologique (biocompatibilité, prolifération et différentiation cellulaires avec des biomatériaux). Le but vise à développer une nouvelle méthode de recouvrement d’implants osseux par des techniques laser pulsé avancées (PLD – Pulsed Laser Deposition et MAPLE - Matrix Assisted Pulsed Laser Evaporation). Ces techniques sont utilisées pour la synthèse d’un système biphasique composé de nanoparticules d’hydroxyapatite (HA) associées à des protéines d’adhérence type fibronectine (FN) et vitronectine (VN) déposées sur un substrat type titane. Le support métallique permettra de maintenir la rigidité mécanique, l’hydroxyapatite favorisera la bio-intégration dans le tissu osseux et les protéines accélèreront l’adhérence cellulaire. L’objectif principal est d’accélérer l’adhérence des cellules et formation des tissus sur les implants. Les études de prolifération et différentiation cellulaire suggèrent une prédisposition des cellules à la prolifération induite par les revêtements VN et à la différentiation stimulée par les revêtements FN. Les effets significatifs sur l’attachement, l’adhésion et la prolifération observés dans nos études sont très importants pour la première phase de stabilité mécanique d’un implant. Les couches HA/protéines déposées par laser pourraient permettre de réduire cette phase. / The work presented within the thesis concern the fabrication of biomimetic nanostructured biomaterial thin films by pulsed laser techniques and their evaluation from the physico-chemical and biological (cellular biocompatibility, proliferation and differentiation) points of view. The aim is to develop a new method for coating the osseous implants by advanced pulsed laser techniques (PLD – pulsed laser deposition and MAPLE – matrix assisted pulsed laser evaporation). These techniques are used for the fabrication of a biphasic system composed of hydroxyapatite (HA) nanoparticules associated with large adhesion proteins as e.g. fibronectin (FN) and vitronectin (VN) deposited on a titanium substrate. The metallic substrate will allow keeping the mechanical rigidity; the hydroxyapatite will favor the bio-integration in the osseous tissue while the proteins will accelerate the cellular adhesion. The main objective is to speed up the cellular adhesion and the formation of new tissue around the implant. The cellular proliferation and differentiation studies demonstrated a predisposal to cell proliferation induced by the VN coatings and to cell differentiation by FN. The significant effects on the cell adhesion, proliferation and differentiation observed in our studies are of great importance for the mechanical stability phase of the implant. The layers HA/proteins deposited by laser could reduce the time of this phase.

Quantum memories are key components in photonics-based quantum information processing networks. Their ability to store and retrieve information on demand makes repeat-until-success strategies scalable. Warm alkali-metal vapours are interesting candidates for the implementation of such memories, thanks to their very long storage times as well as their experimental simplicity and versatility. Operation with the Raman memory protocol enables high time-bandwidth products, which denote the number of possible storage trials within the memory lifetime. Since large time-bandwidth products enable multiple synchronisation trials of probabilistically operating quantum gates via memory-based temporal multiplexing, the Raman memory is a promising tool for such tasks. Particularly, the broad spectral bandwidth allows for direct and technologically simple interfacing with other photonic primitives, such as heralded single photon sources. Here, this kind of light-matter interface is implemented using a warm caesium vapour Raman memory. Firstly, we study the storage of polarisation-encoded quantum information, a common standard in quantum information processing. High quality polarisation preservation for bright coherent state input signals can be achieved, when operating the Raman memory in a dual-rail configuration inside a polarisation interferometer. Secondly, heralded single photons are stored in the memory. To this end, the memory is operated on-demand by feed-forward of source heralding events, which constitutes a key technological capability for applications in temporal multiplexing. Prior to storage, single photons are produced in a waveguide-based spontaneous parametric down conversion source, whose bespoke design spectrally tailors the heralded photons to the memory acceptance bandwidth. The faithful retrieval of stored single photons is found to be currently limited by noise in the memory, with a signal-to-noise ratio of approximately 0.3 in the memory output. Nevertheless, a clear influence of the quantum nature of an input photon is observed in the retrieved light by measuring the read-out signal's photon statistics via the g⁽²⁾-autocorrelation function. Here, we find a drop in g⁽²⁾ by more than three standard deviations, from g⁽²⁾ ~ 1.69 to g⁽²⁾ ~ 1.59 upon changing the input signal from coherent states to heralded single photons. Finally, the memory noise processes and their scalings with the experimental parameters are examined in detail. Four-wave-mixing noise is determined as the sole important noise source for the Raman memory. These experimental results and their theoretical description point towards practical solutions for noise-free operation.

Du fait de leur compacité, leur robustesse et leur faible coût, les microlasers impulsionnels nanosecondes constituent des sources particulièrement attractives pour de nombreux systèmes de détection et d'analyse, en particulier les cytomètres en flux ou les dispositifs pour la spectroscopie CARS (Coherent Raman Anti Stokes Scattering). Cependant, ces applications nécessitent des performances améliorées en ce qui concerne la gigue temporelle et la cadence de répétition accessible. Dans sa première partie, cette thèse propose des solutions originales pour atteindre les performances requises à partir de microlasers passivement déclenchés, grâce à la mise en oeuvre d'une cavité hybride couplée, pompée par une onde modulée en intensité. Une cadence de répétition supérieure à 30 kHz avec une gigue demeurant inférieure à 200 ns est atteinte. Le potentiel de microlasers à fibres déclenchés par modulation du gain pour monter en cadence est aussi évalué, montrant que des impulsions à faible gigue, à une cadence de plus de 2 MHz peuvent être produites. Enfin, la dernière partie est consacrée à la mise au point et à l'exploitation d'un nouveau système de spectroscopie CARS assisté par une excitation électrique haute tension. Ce dispositif, réalisé à partir d'un microlaser amplifié, permet de s'affranchir du bruit de fond non résonnant des mesures et de réaliser une analyse spectroscopique fine de la réponse de différents milieux d'intérêt sous champ continu ou impulsionnel, pouvant conduire à une nouvelle méthode de microdosimétrie de champ. Diverses applications, dont la granulométrie à l'échelle micro ou nanométrique ou l'identification de marqueurs pour la biologie, sont démontrées. / Thanks to their compactness, robustness and low cost, pulsed nanosecond microlasers are particularly attractive sources for different detection and analysis systems, particularly flow cytometers or devices for CARS (Coherent Anti Raman Stokes Scattering) spectroscopy. However, these applications require reduced time jitter and increased repetition rate. The first part of this thesis proposes novel solutions to achieve the required performance from passively Q-switched microlasers, which are based on an hybrid coupled-cavity and intensitymodulated pump wave. A repetition rate greater than 30 kHz with jitter remaining lower than 200 ns is reached. Pulsed fiber microlasers operating by gain switching are also studied, showing that pulses with low timing jitter, at a repetition rate of more than 2 MHz can be obtained. The last part is devoted to the development and the implementation of a new system of CARS spectroscopy assisted by a high-voltage electrical stimulation. This device, based on an amplified microlaser, allows to substract the non-resonant background noise in the measurements. Thus, a fine spectroscopic analysis of the response of different environments of interest in continuous or pulsed field can be achieved. It may lead to a new method for field microdosimetry. Various applications, including granulometry at the micro or nanometric scale and the identification of markers for biology, are shown.