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Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2020. Durante las etapas iniciales de la formación estelar se desencadenan procesos de eyección de vientos a lo largo del eje de rotación. La interacción de estos vientos con el material circunestelar es observables en un amplio rango de longitudes de onda y dan origen a los llamados “outflows”, observados en longitudes de onda infrarrojas y de radio, que en el rango óptico se manifiestan como “jets” y/u objetos Herbig-Haro (HH). En esta Tesis Doctoral se presenta un estudio observacional multi-frecuencia de tres jets estelares lejanos que se encuentran en diversos entornos de formación y con morfologías sinusoidales: MHO 1502, MHO 2147 y HH 137-138. Se utilizaron datos propios obtenidos en el infrarrojo cercano con el instrumento GSAOI+GeMS del telescopio Gemini Sur, y en el submilimétrico con el receptor SHeFI, del radiotelescopio APEX. Para complementar los estudios multibanda, se emplearon imágenes extraídas de bases de datos públicas de los telescopios Spitzer, WISE y Herschel, en el infrarrojo medio y lejano, y del relevamiento ATLASGAL en el submilimétrico. El estudio no sólo indaga sobre las propiedades de los jets, sino también de la nube circundantes y de las estrella excitatrices. Además, se analiza la relación entre la morfología serpenteante de los jets y la binaridad/multiplicidad de la fuente generadora. During the early stages of star formation, wind ejection processes are triggered along the rotation axis. The interaction of these ejections with the circumstellar material is observable over a wide range of wavelengths and give rise to so-called "outflows", detected at infrared and radio wavelengths, which in the optical range manifest themselves as "jets" and/or Herbig-Haro (HH) objects. This PhD Thesis presents a multi-frequency observational study of three distant stellar jets found in different formation environments and with sinusoidal morphologies: MHO 1502, MHO 2147 and HH 137-138. We used our own data obtained with the GSAOI+GeMS instrument of the Gemini South telescope in the near-infrared, and with the SHeFI receiver of the APEX radio telescope in the submillimetre. To complement the multi-band studies, images extracted from public databases of the Spitzer, WISE and Herschel telescopes in the mid- and far-infrared and from the ATLASGAL survey in the submillimetre were used. The study investigated not only the properties of the jets but also the surrounding clouds and the exciting sources. Furthermore, the relation between the wiggling stelar jets and the binarity/multiplicity of the generating source is analysed Fil: Ferrero, Leticia Virginia. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.

The fundamental semiconductor concept of doping has recently been transplanted to photonics in the platform of epsilon-near-zero (ENZ) media. By doping nonmagnetic impurities, ENZ media can exhibit almost arbitrary magnetism. However, this original photonic doping approach results only in isotropic media and thus cannot achieve impedance matching for all incident angles. We extend the photonic doping approach of ENZ media by adding anisotropy, which enables full transparency with omnidirectional impedance matching. More importantly, such anisotropically doped ENZ media preserve their material parameters under arbitrary coordinate transformations, thereby providing a powerful platform to construct various ideal transformation optical devices. As an example, a full-parameter omnidirectional invisibility cloak is demonstrated to hide objects from a wide range of incident angles. The transformation-invariant material proposed not only supplements and extends the rising technologies of ENZ media but also constitutes a significant step towards the practical implementation of ideal transformation optical devices. Published version

The surface integral equation (SIE) method, discretized with the method of moments, is a well-established methodology for the scattering analysis of subwavelength plasmonic nanoparticles. SIEs are usually discretized with low-order basis functions that preserve the normal continuity of the surface currents across the edges arising in the meshed boundary, such as Rao-Wilton-Glisson (RWG) functions. However, the plasmonic enhancement modeling on sharp-edged particles is an extremely challenging task, especially due to the singular fields exerted at sharp corners, exposing a slow (or no) convergence in the computation of the scattering and absorption spectra. In this paper, we propose an alternative discretization strategy based on a discontinuous basis function set in conjunction with a volumetric-tetrahedral testing scheme. We demonstrate the potential of the proposed discretization scheme by studying scattering and absorption spectra of three canonical plasmonic polyhedra, i.e., a hexahedral, an octahedral, and a tetrahedral silver inclusion. The results expose an improved accuracy and faster convergence in both far-field and near-field regions when compared to the standard RWG implementation. The proposed discretization scheme can offer faster and more accurate routes towards the exploration and design of the plasmonic resonant spectrum of sharp-edged nanoparticles and nanoantennas.

International audience; This communication deals with the optical characterization of droplets and fluids parameters that are relevant for liquid-liquid extraction processes, and notably, for nuclear fuel reprocessing. In immiscible liquid-liquid dispersions, i.e. droplets with a homogeneous but low value relative refractive index, the first order rainbow is localized in the near forward to sideways region. It exhibits also an unusual higher contrast for a parallel polarization illumination. Nevertheless, it is possible, considering appropriate light scattering models and inverse methods, to derive from its analysis the droplets' size and composition. When a mass transfer occurs, the refractive index of the droplets and the surrounding fluid become inhomogeneous. In a pure molecular diffusion regime, the rainbow patterns can still be interpreted as well, allowing the estimation of relevant properties for chemical engineering processes, like molecular diffusivities or the distribution constant. 1 Immiscible systems-homogeneous droplets We first consider that the extraction process is already completed or has not yet started [1]. The composition of the single or cloud of droplets is thus homogeneous. For obvious safety reasons, simulant and mixing fluids (TPH and Marcol) were used in this study in place of the real fluids involved in nuclear fuel reprocessing. TPH is the diluent employed in the actual process, while Marcol is a saturated hydrocarbon liquid with a higher refractive index than TPH but with comparable viscosity and surface tension. In the same way, for the continuous phase, demineralized water (HPLC-grade) replaces the nitric aqueous solution used in the process.; Cette communication traite de la caractérisation optique des gouttelettes et des paramètres fluides pertinents pour les procédés d'extraction liquide-liquide, et notamment, pour le retraitement du combustible nucléaire. Dans les dispersions liquide-liquide non miscibles, c'est-à-dire des gouttelettes avec un indice de réfraction relatif homogène mais de faible valeur, l'arc-en-ciel de premier ordre est localisé dans la région proche de l'avant vers les côtés. Il présente également un contraste plus élevé inhabituel pour un éclairage à polarisation parallèle. Néanmoins, il est possible, en considérant des modèles de diffusion de la lumière appropriés et des méthodes inverses, de déduire de son analyse la taille et la composition des gouttelettes. Lorsqu'un transfert de masse se produit, l'indice de réfraction des gouttelettes et du fluide environnant devient inhomogène. Dans un régime de diffusion moléculaire pure, les motifs arc-en-ciel peuvent également être interprétés, permettant l'estimation de propriétés pertinentes pour les processus de génie chimique, comme les diffusivités moléculaires ou la constante de distribution. Systèmes non miscibles-gouttelettes homogènes Nous considérons d'abord que le processus d'extraction est déjà terminé ou n'a pas encore commencé. La composition de l'unique ou du nuage de gouttelettes est ainsi homogène. Pour des raisons de sécurité évidentes, des fluides simulants et de mélange (TPH et Marcol) ont été utilisés dans cette étude en lieu et place des fluides réels impliqués dans le retraitement du combustible nucléaire. Le TPH est le diluant utilisé dans le processus réel, tandis que le Marcol est un liquide d'hydrocarbure saturé avec un indice de réfraction plus élevé que le TPH mais avec une viscosité et une tension superficielle comparables. De même, pour la phase continue, de l'eau déminéralisée (qualité HPLC) remplace la solution aqueuse nitrique utilisée dans le procédé.

We report on the coupling of an electric quadrupole transition in atom with plasmonic excitation in a nanostructured metallic metamaterial. The quadrupole transition at 685 nm in the gas of Cesium atoms is optically pumped, while the induced ground state population depletion is probed with light tuned on the strong electric dipole transition at 852 nm. We use selective reflection to resolve the Doppler-free hyperfine structure of Cesium atoms. We observed a strong modification of the reflection spectra at the presence of metamaterial and discuss the role of the spatial variation of the surface plasmon polariton on the quadrupole coupling., Comment: 6 pages, 5 figures

International audience; We theoretically discuss the link between the phase measured using a scattering optical scanning near-field microscopy (s-SNOM) and the local density of optical states (LDOS). A remarkable result is that the LDOS information is directly included in the phase of the probe. Therefore by monitoring the spatial variation of the trans-scattering phase, we locally measure the phase modulation associated with the probe and the optical paths. We demonstrate numerically that a technique involving two-phase imaging of a sample with two different sized tips should allow to obtain the image the pLDOS. For this imaging method, numerical comparison with extinction probe measurement shows crucial qualitative and quantitative improvement.