La tenue au flux des traitements de surfaces optiques constitue aujourd'hui un enjeu majeur pour le développement des lasers de puissance à courtes durées d'impulsion. L’étude des interactions laser-matière en régime sub-picoseconde a montré que l’initiation de l'endommagement laser est le résultat de processus d’excitation fortement non-linéaires (photoionisation, ionisation par impact et avalanche électronique). Dans cette thèse, un dispositif de tests multiparamétriques a été développé pour l’étude de la tenue au flux des composants optiques. Différentes études expérimentales ont été menées sur des matériaux diélectriques, en couche mince ou en matériau massif, afin d’apporter des données nouvelles sur les matériaux couches minces assez peu étudiés dans la littérature. L’étude de l’influence de la longueur d’onde a révélé différentes phases de prédominance des processus d’ionisation. L’influence du nombre de tirs à différentes longueurs d’ondes aussi a été étudiée, en considérant différentes techniques de dépôt de couches minces. L’interprétation de ces résultats expérimentaux est soutenue par un modèle de simulation numérique que nous présentons en détail dans le manuscrit. Une place, non moins importante, a été accordée dans notre travail à la métrologie de l’endommagement. Nous avons proposé et appliqué l’utilisation d’un dispositif original de mesure quantitative de phase pour l’analyse des processus d’endommagement. Et pour terminer nous avons développé un système de microscopie pompe-sonde afin de pousser les investigations sur les processus en jeu lors de l’interaction laser-matière en régime sub-picoseconde. / Laser fluence resistance of optical surfaces is a major challenge for the development of high power and short duration pulse lasers. Studies on laser matter interactions show that the damage initiation is the result of highly nonlinear excitation process such as photoionization, impact ionization and electronic avalanche. In this PhD thesis we focused on the study of the damage and the response of materials after this initiation and their dependence with laser parameters, this in order to better understand the complex mechanisms of damage, identify laws of relevant scales for applications, and enable new optical design with higher laser resistance and lifetimes. A multi parametric experimental testing setup was developed for studying laser resistance of optical components. To collect new data on thin film materials damage dependences, which have been less studied in the literature, different experimental studies have been conducted on dielectrics, in coating or bulk form. The study of the dependency of damage with laser wavelength reveals different ranges characterized by the electronic processes occurring during the interaction. We have considered also the effect of multiple pulse irradiations, with different wavelengths and on coatings realized by different technologies. All these experimental results have been discussed with the help of a numerical simulation model we have developed and presented in this thesis. We have also proposed an original method based on optical phase difference measurement for damage characterization and study. We finished with some experiments on the time resolved microscopy measurements and investigations of damage processes.

In the past decades, the miniaturization in optics led to new devices with structural sizes in the range of the light wavelength, where the photonic modes are con- fined and the number of states is limited. In the smallest microcavities, i.e. micrometer sized optical resonators, the propagation of only one mode is permitted that is simultaneously amplified internally. This particularly strong enhancement of the electric field is directly related to the quality factor of the cavity. By introducing an optical dipole into a high-Q microcavity, the spontaneous emission is amplified at the cavity mode frequency enabling stimulated emission in an inverted system. Although some of theses cavity e®ects can only be understood by quantum elec- trodynamic theory, most mechanisms are accessible by classical and semi-classical approaches. In this thesis, one-dimensional planar microcavities with quality factors up to 4500 have been fabricated by physical vapor deposition of dielectric thin films and organic active materials. A new cavity design based on anisotropic dielectric mirrors grown by oblique angle deposition microcavities with two energetically shifted orthogonally polarized modes is presented. The application of these anisotropic structures for terahertz di®erence signal generation is demonstrated in spectrally and time resolved transmission experiments, where optical beats with repetition rates in the terahertz range are observed. Optically pumped organic vertical cavity surface emitting lasers (VCSELs) have been realized by applying an organic solid state laser compound and high reflectance distributed Bragg reflectors. These lasers combine a very low laser threshold with small beam divergence and good stability. A transfer of the anisotropic design towards an organic VCSEL results in the generation of two perpendicularly polarized laser modes with a splitting adjustable by the fabrication conditions. The observation of an oscillation of two laser modes in a photomixing experiment proves a phase coupling mechanism. This demonstrates the potential of the anisotropic cavity design for a passive or active component in a terahertz radiation source or frequency generator. Furthermore, microcavities with two and three coupled resonators are investigated. By the application of time-resolved transmission experiments, spatial oscil- lations of the internal electric field - photonic Bloch oscillations - are successfully demonstrated. In combination with the anisotropic microcavities, this is a second concept for the modulation of transmitted light with terahertz frequencies. All experiments are accompanied by numerical or analytical models. Transmission experiments of continuously incident light and single laser pulses are compared with transfer matrix simulations and Fourier transform based approaches. For the modeling of emission experiments, a plane wave expansion method is successfully used. For the analysis of the organic VCSEL dynamics, we apply a set of rate equations that explains the gain switching process.

Im Rahmen dieser Arbeit wurde ein Niedertemperatur Sol-Gel Spin-Coating Verfahren entwickelt, mit dem sich Metalloxide und -fluoride in Form von Nanometer-dicken Schichten abscheiden lassen. Ziel dieses Verfahrens ist die Herstellung von anti- (AR) und hoch reflektierenden (HR) Schichtsystemen, die aus einem alternierenden Aufbau von niedrig brechenden und hoch brechenden Materialien bestehen. Zur Darstellung der Metallfluoride wurde dabei eine neuartige nichtwässrige Sol-Gel Synthese ausgehend von Metallalkoxiden und in Alkoholen einkondensiertem Fluorwasserstoff angewendet. Die abgeschiedenen Schichten, die bei 100 °C getrocknet wurden, sind mit REM, TEM und AFM auf ihre morphologische Struktur, mit EDX und XPS auf ihre chemische Zusammensetzung und mit Ellipsometrie und UV-vis Transmissionsspektroskopie auf ihre optischen Eigenschaften hin untersucht worden. Mit diesem Verfahren gelang die Präparation von homogenen MgF2- und TiO2-Schichten mit geringen Rauheiten (Ra < 2,0 nm) auf Si- und SiO2-Substraten. Die MgF2-Schichten haben einen Brechungsindex von n500 = 1,36. Die TiO2-Schichten weisen einen Brechungsindex von n500 = 2,05 auf. Die Dicken der MgF2- und TiO2-Schichten sind zwischen 25 nm und 500 nm einstellbar. Durch einen alternierenden Aufbau von MgF2- und TiO2-Schichten gelang außerdem erstmalig die Herstellung von Metallfluorid- und Metalloxid-basierten Schichtsystemen über einen Niedertemperatur Sol-Gel Prozess. Mit Hilfe der bestimmten optischen Eigenschaften der MgF2- und TiO2-Einzelschichten wurden einfache AR und HR Designs entwickelt und aufgebaut. Die Transmissionsspektren der Designs und der jeweiligen Schichtsysteme zeigten dabei gute Übereinstimmungen, gleiches galt für die mit Hilfe der Spektralellipsometrie aufgenommenen Reflexionsspektren. In dieser Arbeit konnte erstmals gezeigt werden, dass sich das Niedertemperatur Sol-Gel Verfahren prinzipiell zur Herstellung von einfachen AR und HR Schichtsystemen eignet. / This work deals with the development of a low temperature sol-gel spincoating process for thin films with thicknesses in the nanometer range based on metal oxides and metal fluorides. Optical films such as anti-reflective (AR) or high reflective coatings are of much interest and consist of alternating dielectric layers of low and high refractive index materials. Regarding the general procedure for the metal fluorides a novel nonaqueous sol-gel synthesis starting from metal alkoxides and alcohol-dissolved HF was used. The coatings were dried and calcined at 100 °C. The morphology of these films was characterised with REM, TEM and AFM. EDX and XPS were used to indentify the chemical composition and ellipsometry and UV-vis spectroscopy to determine the optical properties of the films. This new process allows the preparation of homogeneous magnesium fluoride and titanium dioxide layers with low roughness (Ra < 2.0 nm) on Si and SiO2 substrates. The thicknesses of the MgF2 and TiO2 single layers were adjustable between 25 nm and 500 nm depending on the number of coating steps and on the concentration of the used sols. The MgF2 layers had a refractive index of n500 = 1.36 and the TiO2 layers a refraction index of n500 = 2.05. For the first time, an alternating metal fluoride and oxide multilayer system was produced with a low temperature sol-gel method (consisting of MgF2 and TiO2). Based on the determined optical constants of the MgF2 and TiO2 single layers, AR and HR multilayer systems were calculated and fabricated. The transmission spectra of the designs and the corresponding multilayer were in good agreement. Similar results were obtained with the reflection spectra determined with spectral ellipsometry. The presented investigations were able to show that the developed low temperature sol-gel process using the spin-coating technique is suitable for the preparation of simple AR and HR multilayer systems.

No description available.