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Because compact solid-state blue/green lasers can generate high power, and short wavelength radiation, it is applied in micromaching, laser display, underwater ranging, and so forth. It is a very cost-effective approach to develop such lasers, if the laser output characteristics can be estimated precisely using software simulation. The purpose of this study is to use an optics software GLAD (General Laser Analysis and Design) to model our intracavity frequency-doubled blue/green lasers. The GLAD software considers the wave nature of laser, such as dispersion and diffraction. Moreover, it employs a modular design in modeling linear or nonlinear optical components. In order to get more precised estimation of the laser output characteristics of a quasi-three-level laser, the laser model in GLAD was modified to take into account the reabsorption loss in gain medium. In our experiment, blue/green microchip lasers were developed. We used a 3W LD to pump a quasi-three-level laser with the Nd:YAG crystal as gain medium and KNbO3 crystal as the intracavity SHG crystal for the generation of blue laser. The laser generates 17.6 mW of blue power with a cavity length of 4 mm. With almost the same structure except using Nd:YVO4 crystal as gain medium and KTP crystal as the intracavity SHG crystal for generation of green laser, the laser produces 627 mW of green power with a cavity length of 6 mm.

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Cette thèse est dédiée à l’élaboration de couches minces d'oxydes de tungstène par pulvérisation cathodique réactive. Afin de jouer sur la composition des films, le procédé de pulsation du gaz réactif (RGPP) est mis en œuvre pour changer les concentrations en oxygène et en tungstène. En parallèle, la technique de dépôt sous incidence oblique (GLAD) est développée pour produire différentes architectures, à savoir des colonnes inclinées, des zigzags ou encore des spirales, et augmenter le rapport surface-volume dans les films. La co-pulvérisation GLAD est également étudiée en utilisant deux cibles inclinées et séparées de W et WO3. Les relations entre la microstructure, la composition, les propriétés électroniques et optiques des films d'oxydes de tungstène sont systématiquement étudiées. Ils sont finalement appliqués comme couches actives pour des capteurs résistifs afin d'améliorer la détection de vapeur de dodécane et d'ozone gazeux. La microstructure poreuse élevée des colonnes inclinées produite par GLAD combinée à une composition ajustée par RGPP conduit à définir une gamme de films d'oxydes de tungstène attractifs pour améliorer les performances capteurs. / This thesis is focused on the reactive sputter deposition of W-O thin films. In order to play with their composition, the Reactive Gas Pulsing Process (RGPP) is implemented and allows tunable oxygen and tungsten concentrations. Similarly, the GLancing Angle Deposition (GLAD) technique is developed to produce various architectures, namely inclined columns, zigzags and spirals, and increases the surface-to-volume ratio of the films. The GLAD co-sputtering approach is also investigated by means of two inclined and separated W and WO3 targets. Relationships between microstructure, composition, electronic and optical properties of W-O films are systematically studied. They are finally applied as active layers for resistive sensors in order to improve detection of dodecane vapor and ozone gas. The high porous microstructure of inclined columns produced by GLAD combined to the suitable composition adjusted by RGPP leads to define a range of W-O films attractive for sensing performances.

In this work samples with silver nanocolumnar structures were successfully fabricated by glancingangle deposition. From SEM investigations of the samples it is concluded that distinct andseparated nanocolumns can be grown without pre-patterned substrates using this method (givensuitable deposition conditions). The sample that exhibits the most distinct and well separatedcolumns was modelled using HFSS with optical properties of silver in nanocolumns obtained bymeasurements on the samples grown by glancing angle deposition, thin enough to not havedeveloped columns. From numerical calculations it was shown that the unit cell arrangement of thecolumns has a large influence on the optical characteristics. It was found that a diamond-like unitcell designed as two identical square lattices shifted by half the lattice spacing in one direction and2-1/2 times the lattice spacing of the other direction gives the best and a fair agreement to theexperimental ellipsometry data. Based on this model calculations were made to determine thewavelength dependent average local current exhibited in the columns as well as the currentdensity. This study showed the occurrence of broadbanded plasmon resonances of longitudinalmode at λ=1363 nm and of transverse mode at λ=545 nm. It was also shown that the opticalcharacteristics are strongly polarization dependent as is expected for such anisotropic samples.

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Title: SERS spectroscopy of model biomolecules for SERS biosensing Author: Martin Šubr Department: Institute of Physics of Charles University Supervisor: doc. RNDr. Marek Procházka, Dr., Institute of Physics of Charles University Abstract: The main requirement for surface enhanced Raman scattering (SERS)-based biomolecular sensing is high sensitivity and spectral reproducibility. For this purpose, ordered silver and gold nanostructures fabricated by magnetron sputtering and lithography methods at cooperating institutes were tested in this work. Reproducible SERS spectra of employed model biomolecules (amino acids, lysozyme and albumin) were obtained on ordered silver surfaces at concentrations 10-4 M - 10-6 M and as low as ≈ 10-7 M in the case of porphyrins. SERS spectra of certain biomolecules were also compared to spectra measured on silver colloid. The limit of detection provided by hydroxylamine-reduced silver colloid, using KCl as an aggregating agent, is substantially lower (on the order of 10-8 M for cysteine), but with lower spectral reproducibility. The main drawback of SERS spectra measured on silver surfaces was the occurrence of spurious bands resulting from the preparation procedure. In the case of sputter-deposited silver surfaces, it was found that keeping the substrates several hours in...

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Le but de ce travail de recherche a été d’une part, de contrôler le procédé d’élaboration decouches minces d’oxynitrures de silicium par pulvérisation cathodique réactive à partir d’une ciblede silicium ; et d'autre part, de déterminer les caractéristiques structurelles et optiques de cescouches minces pour réaliser des multicouches à propriétés antireflets dans le visible. Des films deSiNy et SiOx ont été élaborés et étudiés selon trois procédés de pulvérisation cathodique réactive. Legaz réactif a été introduit soit en continu (procédé convention : CP), soit périodiquement selon uncréneau exponentiel (procédé RGPP). Le troisième procédé de pulvérisation repose sur l'orientationdu substrat dans l'espace tandis que la source de vapeur reste fixe (technique GLAD). Les analysespar spectroscopie d’électrons et par microscopie électronique ont permis de déterminer lacomposition chimique et la morphologie des films. Les caractéristiques optiques ont étédéterminées par spectroscopie UV-visible-PIR. De plus, des simulations numériques sur lespropriétés fondamentales des structures du nitrure et de l'oxyde de silicium ont été effectuées pouressayer de mieux appréhender les comportements optiques de ces films. Au final, ces travaux ontpermis l'élaboration et l'étude d'empilements multicouches SiNy/SiOx à propriétés antireflets dansles longueurs d'onde du visible sur différents substrats. / This work aims at controlling the deposition process of silicon oxynitride thin films by reactivesputtering from a silicon target. It is also focused on some correlations between structural andoptical properties of the films in order to produce antireflective multilayers. SiNy and SiOx films aresputter deposited by three different reactive processes. A continuous reactive gas injection(conventional process: CP) or a periodical supply by means of exponential pulses is implemented(RGPP process). The third process is based on a controlled orientation of the substrate (GLADtechnique). These films are analyzed by electronic spectroscopy and electronic microscopy forcomposition and morphology, respectively. The optical properties are determined by UV-Vis-IRspectroscopy. Moreover, theoretical simulations on structural silicon nitride and oxide areperformed so as to better understand optical properties of the films. Last but not least, this workleads to the growth and study of SiNy/SiOx antireflective multilayers used in the visible range anddeposited on different kind of substrates.