The deposition of superconducting Nb3 Sn on copper accelerating cavities is interesting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. The magnetron sputtering technology allows the deposition of Nb 3 Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require target with non-planar shape, which are difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD technique is a wire fabrication technology, already developed in the past at LNL for superconducting radio frequency (SRF) applications [2], that allows the deposition of very thick and uniform coating on Nb substrates even with complex geometries [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb 3 Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work.

L'astronomie gravitationnelle a débuté en septembre 2015 avec la première détection de la fusion de deux trous noirs par LIGO. Depuis lors, plusieurs fusions de trous noirs et une fusion d'étoiles à neutrons ont été observées. Advanced Virgo a rejoint les deux observatoires LIGO dans la prise de données en août 2017, augmentant fortement les capacités de localisation du réseau. Afin d'exploiter pleinement le potentiel scientifique de ce nouveau domaine, un énorme effort expérimental est nécessaire pour améliorer la sensibilité des interféromètres. Cette thèse, développée dans ce contexte, est composée de deux parties. La première concerne Advanced Virgo : nous avons développé un budget de bruit automatique pour le bruit de fréquence du laser et nous avons effectué des mesures de caractérisation optique pour les cavités de bras kilométriques. Des pertes aller-retour aussi faibles que 80 ppm ont été mesurées. Elles sont parmi les plus basses jamais mesurées avec un faisceau de cette taille. La deuxième partie concerne la conception et le développement d'une cavité de filtrage de 300 m, un prototype pour démontrer la production de lumière squeezing dépendante de la fréquence avec les propriétés nécessaires pour une réduction du bruit quantique à large bande dans KAGRA, Advanced Virgo et Advanced LIGO. Nous avons contribué à la fois aux phases de conception et d'intégration du projet. Nous avons d'abord fait le design optique de la cavité, y compris les spécifications pour l'optique de la cavité et une estimation détaillée des sources de dégradation pour le squeezing. Nous avons donc développé un système de contrôle pour les miroirs, assemblé les suspensions et finalement aligné et mis la cavité en résonance avec la lumière laser / Gravitational wave astronomy has started in September 2015 with the first detection of a binary black-hole merger by LIGO. Since then, several black-hole mergers and a binary neutron star merger have been observed. Advanced Virgo joined the two LIGO detector in the observation run, in August 2017, highly increasing the localization capabilities of the network. In order to fully exploit the scientific potential of this new-born field, a huge experimental effort is needed to bring the instruments at their design sensitivity and to further improve them. This thesis, developed in this context, it is composed of two parts. The first is about Advanced Virgo: we have developed an automatic noise budget for the laser frequency noise and we have performed optical characterization measurements for the kilometric arm cavities. Round trip Losses as low as 80 ppm have been measured. They are among the lowest ever measured for beams of these size. The second part is about the design and development of a 300 m filter cavity, a prototype to demonstrate the frequency dependent squeezing production with properties needed for a broadband quantum noise reduction in the future upgrades of KAGRA, Advanced Virgo and Advanced LIGO. We have contributed to the design and integration phases of the project. We have first made the optical design of the cavity, including the the specifications for the main cavity optics and a detailed estimation of the squeezing degradation sources. We have then developed a local control system for the mirrors, assembled the suspensions, and finally aligned and brought the cavity in resonance with the laser light

Les cavités sont le lieu privilégié des interactions d’une protéine avec ses ligands, et sont donc déterminantes pour sa fonction, elle-même aussi influencée par la dynamique de la protéine. Peu de méthodes permettent d’étudier en détail la dynamique des cavités malgré leur intérêt notamment pour le criblage virtuel. Les cavités d’une protéine définissent un ensemble très labile. Ainsi, suivre une cavité le long d’une trajectoire est ardu car elle peut être sujette à des divisions, fusions, disparitions et apparitions. Je propose une méthode pour résoudre cette question afin d’exploiter la dynamique des cavités de façon systématique et rationnelle, en classifiant les cavités selon les groupes d’atomes les entourant. J’ai identifié les paramètres procurant les meilleurs critères de suivi des cavités. Pour caractériser les évolutions principales de la géométrie des cavités en relation avec la dynamique de la protéine, j’ai développé une méthode basée sur l’Analyse en Composantes Principales. Cette méthode peut être utilisée pour sélectionner ou construire des conformations à partir de la forme de leurs cavités. Deux exemples d’applications sont traitées : la sélection de conformations ayant des cavités de géométries diverses et l’étude de l’évolution des cavités de la myoglobine lors de la diffusion du monoxyde de carbone. Ces deux méthodes ont été utilisées pour trois projets de criblage virtuel ciblant l’ADN-gyrase de M tuberculosis, la subtilisine 1 de P vivax et GLIC, homologue procaryote des récepteurs pentamériques humains. Les molécules sélectionnées à l’aide de ces méthodes ont permis d’identifier une molécule active contre la subtilisine et quatre effecteurs de GLIC. / Cavities are the prime location of the interactions between a protein and its ligands, and thus are crucial for its functions, together with its dynamics. Although cavities have been studied since the seventies, specific studies on their dynamical behavior only appeared recently. Few methods can tackle this aspect, despite its interest for virtual screening and drug design. Protein cavities define an extremely labile ensemble. Following one cavity along a trajectory is therefore an arduous task, because it can be subjected to several events of fusions, divisions, apparitions and disappearances. I propose a method to resolve this question, thus enabling systematic and rational dynamical exploitation of protein cavities. This method classify cavities using the atom groups around them, using algorithms and parameters that I identified as giving best results for cavity tracking. To characterize the main directions of evolution of cavity geometry, and to relate them with the dynamics of the underlying structure, I developed a method based on Principal Component Analysis (PCA). This method can be used to select or build conformations with given cavity shapes. Two examples of applications have been treated: the selection of conformations with diverse cavity geometries, and the analysis of the myoglobin cavity network evolution during the diffusion of carbon monoxide in it. These two methods have been used in three projects involving virtual screening, targeting M. tuberculosis DNA-gyrase, P vivax subtilisin 1 and GLIC, an procaryotic model of human pentameric ligand-gated ion channel. These methods allowed us to identify an inhibitor of subtilisin 1 and four effectors of GLIC.

Applications of laser absorption spectroscopy for trace gas detection are many and diverse, ranging from the environmental and atmospheric to the medical and industrial. The aim of creating a spectrometer which combines high sensitivities and selectivities (in order to measure small amounts of absorbers or species that are only weakly absorbing, in a complex background matrix) with a wide spectral coverage (to allow broadband absorbers or multi-component samples to be studied) can be realised by implementing three separate concepts: the exploitation of the strong, fundamental transitions of the mid-infrared; the use of sensitive spectroscopic techniques; and the selection of a widely tunable laser source. In this thesis, these ideas are investigated individually and in combination in order to achieve such a goal. Laser spectroscopic techniques based on optical cavities are used to build a high resolution spectrometer covering a large spectral range capable of selectively detecting low levels of gaseous compounds of interest, especially those of medical or environmental significance. Work in both the near- and mid-infrared is presented, including much of the initial, developmental work which was conducted in the former region. The thesis begins with an overview of both narrowband and broadband near-infrared radiation sources, with a particular emphasis on commonly available diode lasers (DLs). A novel laser source, the digital supermode distributed Bragg reector (DS-DBR) laser, is introduced as a useful laser source for spectroscopy, combining the usual benefits of telecom DLs with a wide tunability (1563 – 1613 nm). The laser can be operated in an internal or external ramping mode, allowing the output wavelength to be scanned or stepped across a desired region. The observation of mode-hopping during the application of the scanning methodology is examined and rationalised. The ability of the DS-DBR laser to perform high resolution spectroscopy over its entire spectral coverage is demonstrated by recording spectra of carbon dioxide (CO₂) over this range, covering transitions from two of the four Fermi resonance components of the 3ν₁ + ν₃ combination band. The results of conducting wavelength modulation spectroscopy on CO₂ are also reported. A system developed for performing cavity ring-down spectroscopy (CRDS), capable of the real-time retrieval of ring-down times (RDTs), is presented and discussed. The outcomes of initial tests performed with a conventional DL at 1557 nm, to study a calibrated mixture of CO₂ in air at various pressures, are given. In addition, the results of combining this system with the DS-DBR laser are discussed. The bandwidth of the DS-DBR laser was found to be larger than that of a standard DFB DL, resulting in the presence of noisy cavity modes. Despite this, the acquisition of reproducible RDTs is demonstrated, with single wavelength studies of an evacuated cavity at 1605.5 nm yielding a RDT of 24.54 ± 0.04 µs and Allan variance calculations signalling an attainable minimum detectable absorption coefficient, α_min, of 2.8 x 10^-10 cm^-1 over 20 s. The ability to perform CRDS across the whole DSDBR laser wavelength range without the need for cavity re-alignment is illustrated, and studies conducted on CO₂ in air, calibrated mixtures and breath are reported. Investigations are also described into the accurate determination of the ¹³C/¹²C ratio in exhaled CO₂ undertaken using CRDS and cavity enhanced absorption spectroscopy (CEAS) on CO₂ isotopologues, an approach which can be utilised as a diagnostic aid in determining Helicobacter pylori infection. The focus of the thesis then moves to the mid-infrared, to describe quasi phase matching difference frequency generation (QPM-DFG) and its use to generate laser light at 3 µm by optically mixing near-infrared DLs. The theory behind this non-linear optical interaction is outlined, and the construction of a free-space QPM-DFG system using periodically poled lithium niobate is detailed and characterised. This DL-based QPM-DFG arrangement has been coupled with the CRDS system developed to create a mid-infrared CRD spectrometer. The results of single wavelength studies indicate RDTs of ~ 6 µs and an achievable αmin of 2.9 x 10^-9 cm^-1 over 44 s for an evacuated cavity. Spectroscopic investigations carried out on methane (CH₄), acetone and deuterium are documented; for the latter species, Dicke narrowing of the electric quadrupole ν(1←0) Q(2) transition at 2987.29 cm^-1 is observed and the integrated absorption cross-section for the same transition measured as 2.29 ± 0.03 x 10^-27 cm²cm^-1molec^-1. The results of modifications made to the system, namely the use of a more powerful Nd:YAG laser as the pump radiation source, as well as a faster detector combined with a variable amplifier, are presented; these include the observation of an improved optimal α_min of 6.4 x 10^-10 cm^-1 over 151 s for an empty cavity. Finally, work utilising the DS-DBR laser as one of the near-infrared sources for the QPM-DFG set-up is presented. This configuration generates radiation covering a wide mid-infrared range (3130 – 3330 nm) and has been used to perform direct absorption and wavelength modulation spectroscopy on ro-vibrational transitions within the fundamental ν₃ (F₂) band of CH₄. The spectrum of methanethiol (CH₃SH) over this region has also been investigated, with preliminary studies identifying a feature at 3040 cm^-1 as a potential indicator for monitoring this biomarker in breath. The results of coupling this mid-infrared radiation with an optical cavity to perform CEAS combined with phase sensitive detection are subsequently reported. Studies were conducted on calibrated CH₄ mixtures and ambient air to examine two transitions of the fundamental ν₃ (F₂) band of CH₄ in order to characterise the system: effective path lengths of ~ 700 m and α_min of 6.2 x 10^-8 cm^-1 over 8 s were found. The ^RQ₄ CH₃SH absorption feature at 3040 cm^-1 was also further studied with this system using prepared samples of CH₃SH in N₂ at different concentrations, yielding a CH₃SH detection limit of 2.4 ppm at 19 Torr. The potential of such a cavity-based, DS-DBR sourced, QPM-DFG mid-infrared spectrometer for trace gas sensing having thus been demonstrated, possible improvements that could be implemented to increase the sensitivity of the system are then discussed.

To build multi story buildings out of timber is of a common interest in the building sector. Timber as a building material has many profits, such as the low cost, the availability and the ability to recycle it, the low carbon footprint and the workability. Although, when it comes to fire protection of buildings with a timber based structure there are challenges regarding prevention of the spread of fire while timber surface is exposed to fire. There have been cases in which timber buildings have caught fire leading to severe fire spread and ruined buildings. One example concerns a student modulus accommodation in Luleå that caught fire in august 2013. The fire started on the fourth floor after which a vertical fire spread occurred in concealed spaces between the volume modules. According to the fire investigation lack of knowledge regarding performance of detailed building solutions has led to the poor fire performance of the building. This master thesis mainly consists of a model scale tests that is prepared and performed according to the standard EN 1363-1. The purpose of the test is to investigate the performance of various cavity barriers exposed to fire. The main objective is to examine which temperatures that can be expected at different positions at various cavity barriers when using model scale test as a test method. There are two main kinds of cavity barriers: barriers that are airtight and closed inside the voids of the construction; and ventilated barriers. The most common cavity barriers are the ones that are airtight and closed. The material can be solid wood, gypsum board or mineral wool. The installation areas for these cavity barriers are anywhere, besides where the concealed spaces shall be ventilated and in every joint that shall be sealed using sealant. The ventilated cavity barriers are mounted in concealed spaces where the ventilating function is provided. These concealed spaces are often situated in, for example, ventilated attics, facades and roofs. The purpose of the ventilated barriers is to maintain the air flow in the cavity during regular conditions but also to form a protecting barrier between fire compartments when exposed to fire. The model scale test includes test apparatuses such as thermocouples and a fire resistance furnace with plate thermometers and burners. In addition, a test rig consisting of test specimens and the products to be tested are essential.  In this report, two model scale tests have been performed and prepared according to EN 1363‑1. The test period endured for four hours and the thermocouples measured the temperatures during the whole time. During the first hour the test specimens were exposed to the standard ISO 834 fire curve by controlling the burners in the furnace. After one hour the burners were turned off and the specimens were no longer exposed to fire. The measurements of the temperatures continued during three more hours. After the first two of these three hours the furnace was opened to confer more oxygen in the purpose to record any changes in the temperatures. Results of the performed experiments have indicated parameters that affect the performance of the cavity barriers. The cavity surface itself has an influence to the fire spread. The number of barriers in the cavity and the material properties of the material that is used as the cavity barrier lead to the different protection by those cavity barriers. Some of the tested barriers were plastic covered, which had effect on the performance of the cavity barriers. The dimensions of the barriers, moreover the width and the thickness, are important parameters for the proper function of the barrier. The test results indicate that glowing combustion occurs in the cavity between various cavity barriers.  It can be seen that the temperature rises when the furnace is opened. This indicates the appearance of smouldering since the combustion increases when the amount of oxygen increases, which leads to a temperature rise. Furthermore, the appearance of smouldering (glowing combustion) can be indicated by the observation of the damages of the specimens after the test. The temperatures that may be expected at the unexposed side of the cavity barrier depend on the surface material of the cavity, dimensions, and the material of the cavity barriers. Smouldering is a consequence of the temperature rise in closed cavities between cavity barriers. The performed test endured for approximately four hours and this indicates that fires in cavities can stay for a long time. To ensure the performance of various cavity barriers and verification by a model scale test it is important to perform further experiment and analyses to investigate the effects of the various parameters. To ensure the effectiveness of the performance of the cavity barriers they should be tested in cavities with various widths and various heights. Further investigation of the risk for smouldering is needed with measuring the amount of oxygen and the pressure.

L'objectif de cette étude est de développer un modèle théorique du champ de pression acoustique réfléchi au-dessus d'un réseau constitué de N cavités rectangulaires. Pour cela, une adaptation de la méthode Kobayashi Potentiel (KP) a été effectuée au cas d'une cavité rectangulaire dans un écran rigide à épaisseur non négligeable. Ce modèle ainsi adapté a été généralisé au cas de réseaux contenant plusieurs cavités rectangulaires parallèles, puis étendu au cas de réseaux de cavités rectangulaires non parallèles. Une étude du couplage a été menée pour comprendre la variation de l'interaction acoustique existant entre les cavités en fonction de l'espacement et de la fréquence. Ce modèle a été comparé aux résultats théoriques, issus de la méthode des éléments finis (FEM), et aux résultats expérimentaux obtenus dans une chambre semi-anéchoïque pour une seule cavité, des réseaux de cavités rectangulaires parallèles et non parallèles. La validité du modèle théorique est soutenu par l'accord observé entre les résultats théoriques et expérimentaux / The purpose of this research project was to develop a theoretical model dealing with reflection of acoustic waves over a grating of N rectangular cavities. Thus, the diffracted acoustic fields were determined by adapting the Kobayashi Potential (KP) method to the case of a cavity. Then, this developed model was generalized to the case of parallel rectangular cavities gratings and then extended to the case of non parallel rectangular cavities ones. A study of the coupling was achieved in order to understand the variation in the acoustic interaction between cavities with spacings and frequency. This model was compared with theoretical results obtained from the finite element method (FEM) and experimental results obtained in a semi-anechoic chamber for a single cavity and gratings of parallel and non-parallel rectangular cavities. The validity of the theoretical model is supported by the agreement between the numerical and experimental results observed

A identificação e caracterização geométrica e físico-química de espaços vazios na estrutura tridimensional de proteínas é capaz de agregar informações importantes para guiar o desenho racional de drogas e a caracterização funcional de sítios de ligação e sítios catalíticos. Dessa forma, algumas ferramentas computacionais foram desenvolvidas nas últimas duas décadas, visando efetuar essas caracterizações. Contudo, as ferramentas existentes lidam com uma série de limitações, dais quais merecem destaque a falta de precisão, falta de capacidade de integração em protocolos de larga escala, falta de capacidade de customização e a falta de uma caracterização eletrostática . Tendo em mente estas limitações, desenvolvemos uma nova ferramenta, denominada KV-Finder, com o objetivo de estender as funcionalidades dos programas existentes, fornecendo assim uma caracterização sistemática mais eficiente e mais informativa dos espaços vazios da estrutura tridimensional de proteínas. Através de uma modelagem matricial baseada em um direcionamento realizado pelo usuário, nossa ferramenta identifica e caracteriza espaços vazios em topologias proteicas. O utilitário é capaz de quantificar o volume, a forma, a extensão de sua superfície, os resíduos proteicos que interagem com os espaços vazios e um mapa de cargas parciais da superfície encontrada. Nossa rotina foi integrada com ferramentas gráficas de modelagem molecular, fornecendo uma interação fácil e eficiente com o usuário. A validação de nosso algoritmo foi realizada em um conjunto de proteínas cujos diversos tipos de espaços vazios englobam os mais variados sítios de ligação e sítios catalíticos. O cálculo do volume de cavidades enzimáticas foi efetuado em larga escala, acompanhando a evolução do tamanho de bolsões na superfamília ALDH. Com relação aos outros softwares existentes, nossa ferramenta apresenta uma série de vantagens das quais merecem destaque menor tempo de execução, maior precisão, maior acessibilidade e facilidade de integração com outros programas, além das características únicas de permitir que a busca ocorra em regiões específicas dentro da proteína e de realizar um mapeamento parcial de cargas da superfície encontrada. / The identification and characterization of geometrical and physical-chemical properties in protein vacant spaces aggregates important information for steering rational drug designing and functional characterization of binding and catalytic sites. Therefore, several softwares have been develop during the past two decades in order to perform such characterization. Nevertheless, the existing tools still present a series of limitations such as lack of precision, lack of integrability in large scale protocols, lack of customization capacity and the lack of a proper electrostatic depiction. We developed a new software, dubbed KV-Finder, in order to complement and extend the functionality of existing softwares, providing a systematic and more descriptive portrayal of protein vacant spaces. By employing a user-driven matrix modeling, our tool identifies and characterizes empty spaces in all sorts of protein topologies. The software quantifies the volume, the area and the shape of the surface, the residues that interact with the vacant spaces and a partial charge map of the computed surface. Our routine was integrated with a graphical molecular modeling software, providing the user with a simple and easy-to-use interface. KV-Finder has been validated with a distinct set of proteins and binding sites. The volume computation was carried in large scale, accompanying the evolution of the pocket volume in the ALDH superfamily. Compared with existing software, KV-Finder presents greater precision, greater accessibility and ease of integration in large scale protocols and visualization softwares. Also, the software possesses unique and innovative features such as the ability to segment and subsegment the empty spaces, a electrostatic depiction and a ligand interaction highlight feature.

Les capteurs inertiels basés sur l’interférométrie atomique reposent sur l’utilisation d’atomes froids refroidis à des températures proches du micro-Kelvin et des temps d’interrogation de plusieurs centaines de millisecondes. Ces conditions conduisent à une extension du nuage d’atomes de l’ordre du cm, qui rend difficile leur interrogation efficace par des lasers à profil d’intensité gaussien. Cette thèse vise à développer plusieurs moyens de palier aux contraintes posés par le profil gaussien des lasers et leur intensité limitée. Deux axes principaux sont explorés.D'une part, l'inhomogénéité d'intensité des faisceaux d'interrogation a été adressée par l'étude, la réalisation et la caractérisation de solutions de mise en forme de faisceaux. Un modulateur spatial de phase a notamment été utilisé pour réaliser un faisceau plat en intensité et en phase de 3cm de diamètre. Une solution commerciale mise en vente durant la thèse a finalement été adaptée à une expérience d’interférométrie atomique, et son impact a été caractérisé.D’autre part, l’utilisation actuelle de lasers gaussiens de diamètres centimétriques pour adresser un maximum d’atomes apporte des contraintes sur les puissances utilisées. L’idée de profiter du gain en puissance de cavités optiques émerge dans le domaine et constitue le cœur de ce travail. Plusieurs concepts de résonateurs optiques ont été étudiés pour permettre l’amplification d’un mode de grande taille dans une géométrie compacte. Nous avons réalisé un résonateur dégénéré, intégrant une lentille intra-cavité, et avons étudié l’influence de ses désalignements et des défauts des optiques sur la résonance de grands faisceaux injectés.Ces deux dispositifs et leur couplage ouvrent la voie vers des générations avancées d’interféromètres atomiques, pour des expériences de précision en physique fondamentale ou pour la mise au point de capteurs inertiels à atomes froids compacts. / Inertials sensors based on atom interferometry use cold atom clouds cooled to micro-Kelvin temperatures and interrogation times of a few hundred of milliseconds.These conditions lead to an expansion of the atom clouds reaching centimetric sizes, which leads to difficulties when trying to adress them efficiently with gaussian laser beams.This work aims at developing different means to counteract the constraints brought by these gaussian beams and their limited intensity.Two main axes are explored.On the one hand, the intensity inhomogeneity of the interrogation beams has been adressed by the study, realisation and characterization of beamshaping solutions.One of these solutions has been adapted to an atom interferometry experiment, and its impact characterized.On the other hand, the current use of gaussian beams with centimetric sizes to interrogate as many atoms as possible brings constraints on the laser power.The idea of taking advantage of the optical gain of optical resonators rises in the field and constitutes the heart of this work.Different optical resonators concepts have been considered to allow the resonance of a large optical mode in a compact geometry.We built a degenerated optical resonator, with an intra-cavity lens, and studied the influence of misalignments and opticals defects on the resonance of large injected gaussian beams.These two devices and their combination open the way towards a generation of advanced atom interferometers, for precise experiments of fundamental physics or the development of compact cold atom inertial sensors.

This research focuses on the effect of several convex and concave nose shapes on cavity formation for both hydrophilic and hydrophobic projectiles. It specifically investigates the effect of convex shape on the threshold velocity for cavity formation as well as the effect of concave shapes on cavity formation in terms of impact velocity, geometry of the concave shape and wettability of the projectile. For the convex cases, the streamlined axisymmetric shape significantly increases the threshold velocity when cavities form and is most pronounced for the ogive and cone. The study demonstrates that measuring the wetting angle and impact velocity is not enough to predict cavity behavior, rather the roughness and nose shape must also be taken into consideration for convex projectiles. For the concave cases, the cavities formed are highly influenced by impact speed and nose shape. Wetting angle did not have any visible effect on the cavity formed at higher impact speeds (7 m/s). The dynamics of the cavity formation are dominated by the pocket of trapped air formed when the concave projectiles impact the water. At low impact speeds (~0-1 m/s) the trapped air can separate the flow from the leading edge of the projectile nose when venting out and cause a large cavity to form, depending on the specific concave shape and speed. At moderate impact speeds (1-4 m/s) the trapped air will vent completely underwater forming a small ring-shaped cavity. At high impact speeds (4-10 m/s) the trapped pocket of air compresses tremendously and causes an unsteady pressure pulse, which can result in the formation of a bubble and jet in front of the cavity. The jet is formed by water passing behind the pocket of trapped air along the walls of the concave nose and converging into a jet at the top of the concave shape and entraining the trapped air as it descends.

Ce travail porte sur la réalisation de dispositifs quantiques fonctionnant en régime de couplage fort entre une excitation d'un gaz d'électrons dans un puits quantique semiconducteur et un mode de cavité dans le moyen infra- rouge. Les quasi-particules issues de ce couplage lumière-matière sont appelées "polaritons intersousbande". La première partie de ce manuscrit est consacrée à l'étude d'un dis- positif électroluminescent basé sur une structure à cascade quantique in- sérée dans une microcavité planaire. Par une analyse détaillée des spectres d'électroluminescence à différents voltages, je démontre que les états de po- laritons sont peuplés de façon résonante, à une énergie qui dépend du voltage appliqué à la structure. Les résultats expérimentaux sont analysés et in- terprétés à l'aide d'un modèle reliant les spectres d'électroluminescence aux propriétés de l'injecteur de la structure à cascade. Pour augmenter la sélectivité de l'injection et observer ainsi une exaltation de l'émission spontanée, un nouveau type de cavité est développé dans la sec- onde partie de ce travail. Il s'agit d'une cavité basée sur un confinement plas- monique, dans laquelle la lumière est confinée entre deux plans métalliques, dans une épaisseur très inférieure à la longueur d'onde. Le miroir supérieur est façonné en réseau. L'influence des différents paramètres du réseau est étudiée et deux régimes sont mis en évidence: un régime où le mode de cavité se couple à un mode de plasmon de surface et un régime où le mode de cavité ne présente pas de dispersion en énergie. En insérant des puits quantiques dopés dans une cavité de ce deuxième type, les régimes de couplage fort puis de couplage ultra-fort lumière-matière sont démontrés jusqu'à température ambiante. La valeur importante du dédoublement de Rabi et la forte densité d'états polaritoniques obtenues dans ce type de cavité en font un candidat très prometteur pour la réalisation de dispositifs électroluminescents infrarouges de grande efficacité radiative et fonctionnant sans inversion de population.