Photonic crystals (PhCs) are periodically structured electromagnetic media, generally characterised by not permitting light of defined ranges of frequency to propagate through the structure. These disallowed ranges of frequency are known as photonic band gaps. The intentional introduction of defects into the crystal gives rise to localized electromagnetic states that provide a mechanism for the control of the propagation of photons through PhCs. In the case of one dimensional (1-D) PhCs, the introduction of a single defect into a finite PhC results in the formation of a resonant cavity structure, a so-called microcavity. The ease of fabrication and scope for integration make 1-D PhCs good candidates for the future applications of PhCs in light transmission systems and, as such, these structures are the focus of the research reported here. The aim of this thesis is to report a practical study of passive 1-D PhC devices and thereby extend the base of measurements that support and extend the results of theory and simulation. Various types of 1-D PhC structures have been fabricated using electron beam lithography and inductively coupled plasma technologies in a clean-room environment. The fabricated structures in effect demonstrate a first or primitive level of integration of 1-D PhCs with another optical device, namely a ridge waveguide. Measurements were performed by butt-coupling from a single mode fibre taper of the transmission characteristics of the resulting integrated waveguides, whilst a Side-band measurement method for very high resolution (0.2pm) microcavity characterisation was invented during the measurement process. A multiple wavelength transmission optical filter transmitting at the telecommunication wavelengths of 1310nm and 1550nm, and which could be used in a WDM system was demonstrated. The effect of introducing mode matching structures to minimize II the scattering loss and boost the quality factor value was investigated. Optimum positioning of the tapers produced a significant enhancement of Q. Finally, a narrow pass band filter constructed from coupled cavities was fabricated and characterised. A quasi-flat transmission peak with a pass band width of just 4nm was observed.

La thermoélectricité rencontre un intérêt croissant ces dernières années comme source d'énergie alternative pour l’alimentation de dispositifs micro- et nano- électroniques. Les matériaux thermoélectriques transforment par effet Seebeck une différence de température en énergie électrique utile. Dans les dispositifs thermoélectriques, l’énergie perdue en général sous forme de chaleur résiduelle peut ainsi être recyclée en utilisant les gradients de température existants. L'efficacité thermoélectrique dépend des propriétés électroniques du matériau et de sa conductivité thermique κ. Le silicium présente une très bonne conductivité électrique et un coefficient Seebeck prometteur, mais sa conductivité thermique phononique limite fortement son potentiel pour des applications thermoélectriques, du moins sous forme de matériau massif. Par contre, la nanostructuration du silicium en couches minces, et a fortiori la fabrication de cristaux phononiques permet de réduire fortement la conductivité thermique. Dans ce travail, des simulations de dynamique moléculaire sont réalisées pour confirmer cette stratégie et permettre la définition d'un design optimal de membranes perforées. De plus, le travail expérimental montre différentes méthodologies de fabrication de membranes phononiques de silicium intégrées dans une plate-forme de métrologie. Plusieurs techniques de caractérisation (Electrothermique, Raman et Microscopie à sonde thermique) ont ensuite été utilisées pour déterminer la conductivité thermique des membranes. Une réduction considérable de κ est obtenue pour le silicium, permettant d’envisager l’intégration de ces membranes dans un convertisseur thermoélectrique. / In the last twenty years, the continuous seek for alternative energy sources to power micro- and nano-electronic devices has marked the rise of interest toward thermoelectricity. Thermoelectric materials can turn directly, by Seebeck effect, the temperature difference into useful electric power. The energy lost as waste heat can be re-used as a power source. It is known that, to improve thermoelectric efficiency, an important role is played by material’s electronic properties and its thermal conductivity. Silicon exhibits very good electrical conductivity and Seebeck parameter, but its lattice thermal conductivity represents the bigger obstacle for thermoelectric applications, preventing its direct integration as bulk material. It has been demonstrated that nanostructuring silicon in thin films enables the reduction of thermal conductivity down to one order of magnitude. Furthermore, a supplementary decrease of thermal conductivity is possible by periodical patterning of the silicon thin film in a photonic-like way, creating Phononic Crystals (PnCs). In our work molecular dynamics simulations are performed to confirm the trend envisaged and allow the definition of an optimal design for the patterned membranes. Moreover, our experimental work lists different fabrication methodologies of silicon phononic engineered membranes integrate into a metrology platform. Several characterization techniques (Electrothermal , Raman thermometry, Scanning Thermal Microscopy) are used to determine the membranes thermal conductivity. A considerable reduction of κ is obtained for silicon, paving the way for a prospective integration of those membranes into a thermoelectric converter.

Pour résoudre la limitation inhérente au procédé d’impression laser LIFT, une approche utilisant une double impulsion (DP-LIFT) a été développée au cours de cette thèse. Dans ce processus, une irradiation laser de durée de quelques dizaines de microsecondes crée un bain de métal en fusion et une seconde impulsion ultra-brève induit le mouvement du fluide, la formation d’un jet ou d’une goutte et le transfert du métal liquide. Cette thèse présente une étude expérimentale détaillée sur le processus DP-LIFT. L'influence des paramètres des deux irradiations laser a été étudiée en s’appyuant sur un ensemble de méthodes d'observation. Pour étudier l’influence de ces paramètres sur la dynamique de l’éjection, un modèle basé sur la conservation de l’énergie a été utilisé. De plus, nous avons démontré que, pour certaines configurations des diamètres respectifs des deux spots lasers, des nanojets focalisés étaient générés. Enfin, en conservant une épaisseur fixe du film métallique, des gouttelettes uniques, sans débris, d'un diamètre allant de 670 nm à 6,0 µm ont été imprimées avec une reproductibilité élevée. des matrices de piliers ont également été imprimées pour démontrer le potentiel de la méthode LIFT à double impulsion pour la fabrication de micro-structures 3D / To solve the inherent limitation of Laser-induced Forward Transfer (LIFT), a double pulse LIFT (DP-LIFT) approach has been developed in this thesis. In this process, a first long pulse laser irradiation creates a melted metal pool and a second ultrashort pulse induces the fluid motion and initiates the jetting transfer. This thesis provides a detailed experimental study on the DP-LIFT process. The influence of double pulse parameters on the jetting phenomena has been carefully studied by means of various observation methods. To predict the jetting behaviors, an energy balanced model has been used. Moreover, we demonstrated that for some configurations of the respective diameters of the two lasers, focused nanojets are generated from the melting pool. Finally, from a fixed thickness of the donor film, debris-free single droplets with diameters ranging from 670 nm to 6.0 µm have been printed with high reproducibility. 2.5 D pillars matrix are printed to demonstrate the potential of the double pulse LIFT method for the fabrication of 3D micro-structures.

Solar cells are at the frontier of renewable energy technologies. Photovoltaic energy is clean, reusable, can be used anywhere in our solar system and can be very well integrated with power distribution grids and advanced technological systems. Thin film solar cells are a class of solar cells that offer low material cost, efficient fabrication process and compatibility with advanced electronics. However, as of now, the conversion efficiency of thin film solar cells is inferior to that of thick crystalline cells. Research efforts to improve the performance bottlenecks of thin film solar cells are highly motivated. A class of techniques towards this goal is called light trapping methods, which aims at improving the spectral absorptivity of a thin film cell by using surface texturing. The precise mathematical and physical characterization of these techniques is very challenging. This dissertation proposes a numerical and computational framework to optimize, design, and fabricate efficient light trapping structures in thin film solar cells, as well as methods to verify the fabricated designs. The numerical framework is based on the important "inverse optimization" technique, which is very is widely applicable to engineering design problems. An overview of the state-of-the-art thin film technology and light trapping techniques is presented in this thesis. The inverse problem is described in details with numerous examples in engineering applications, and is then applied to light trapping optimization. The proposed designs are studied for sensitivity analysis and fabrication error, as other aspects of the proposed computational framework. At the end, reports of fabrication, measurement and verification of some of the proposed designs are presented. / text

The modification of spontaneous emission, i.e. the Purcell effect, with optical cavities has been highly studied over the past 20 years as one of the most important goals for cavity quantum electrodynamics (cQED). The recent development of using surface plasmon resonances to concentrate optical field into sub-wavelength scale further extended cQED research of into a new regime. However, although metallic reflectors are used in some of the earliest demonstrations of cQED, the use of metals is not preferable in high Q optical cavities due to the lossy nature of metals. The presence of metals near an optical emitter also strongly alters its radiation dynamics. As a result, the development of plasmonic cavities brings not only new opportunities but also new problems and challenges. In this thesis we describe four different plasmonic cavity designs along with optical simulations and measurements on them to demonstrate: large spontaneous emission enhancement, controlled mode tuning, and control of the plasmonic band-gap and resonances of high-Q plasmonic cavities for coupling to specific emitters. We hope that our work can guide and inspire researchers who are moving from traditional cavity designs to novel plasmonic devices, helping them to establish design concepts, fabrication criteria, and baselines for characterizing these devices. / Engineering and Applied Sciences

Patterned arrays of metallic nanostructures are commonly used in photonics, electronics, as well as functional materials and biotechnology because of their unique electronic and optical properties. Although great effort has been devoted to the development of nano-patterning techniques in the past decades, there are still existing challenges for nano-fabrication to achieve fine resolution and complex features over macroscopic areas in a reasonable time period. Herein, we devise two versatile patterning strategies, namely indentation colloidal lithography (ICL) and oblique colloidal lithography (OCL), for the stepwise patterning of planar substrates with numerous complex and unique designs. Those strategies combine colloidal self-assembly, imprint molding in conjunction with capillary force lithography and reactive ion etching, all of which are simple and straightforward. Hexagonal arrays of symmetric and nonconcentric gold features are fabricated on glass substrates with highly controllable geometric parameters. The width, size and asymmetry of each surface structure could be tuned down to the ~10 nm level while the scale of the patterned area could exceed 1 cm^(2). Moreover, our technique also leads to the ability to develop an enormous variety of patterns through stepwise amplification of feature types. In particular, some of the features are fabricated for the first time, including target-triangle, hexagram, hexagram-dot and triangle-dot. Distinctive surface plasmon resonance (SPR) properties, such as higher order surface plasmon modes and Fano resonances are both observed from our patterns, which would be highly desired forthe study of plasmonic coupling. In addition, we have demonstrated a surface orientation dependent Raman selectivity on two nano-structures for the first time. Molecular vibrations with opposite symmetries can be selectively enhanced on different substrates. As a demonstration, this property is applied to the odd-even effect of n-alkanethiol self-assembly monolayers (SAMs) on the gold surface. The alternative alternation of the intensity ratios of two vibration pairs have been shown by surface enhanced Raman spectroscopy (SERS) as a function of the number of carbon atoms. The results obtained exhibit high sensitivity and excellent agreement with previous publications.

Ce travail de thèse est consacré au développement de mécanismes pratiques pour le guidage de chaleur dans des nanostructures de silicium de faible dimension. Les applications vont du domaine de la gestion thermique des circuits intégrés aux technologies et matériaux thermoélectriques émergents à base de Si, dans lesquels le guidage thermique de la chaleur peut jouer un rôle important. L'objectif est d'étudier expérimentalement la faisabilité d'une anisotropie de conductivité thermique (κ) dans le plan, induite artificiellement, des membranes nanostructurées en Si. En combinant la thermométrie Raman, la modélisation optique et la modélisation par éléments finis (FEM), il a été possible de mesurer le gradient thermique, la conductance de la membrane et de déterminer les conductivités thermiques effectives. Cette expérience confirme la possibilité d’induire artificiellement une anisotropie élevée de κ dans des membranes en silicium. Un modèle FEM paramétré conçu à dessein a démontré la mise en œuvre possible des effets anisotropes induits dans le domaine de la gestion thermique des circuits intégrés. / This thesis work is devoted to the development of practical mechanisms for the heat guiding in silicon low-dimensional nanostructures. The motivation comes from both the field of IC thermal management and emerging technology of Si-based thermoelectric devices, where directional heat guiding can play an important role. A series of micrometre-sized thermal characterisation platforms was designed and fabricated. The objective is to study experimentally the feasibility of artificially-induced in-plane anisotropy of effective thermal conductivity (κ) in Si nanopatterned membranes. By the combined use of micro Raman Thermometry, Rigorous Coupled Wave Analysis and Finite Element Modelling (FEM) it was possible to measure the thermal gradient, membrane conductance and determine effective thermal conductivities. This experiment confirms the possibility to induce artificially high anisotropy of κ in Si phononic membranes. Finally, purposefully designed parameterized FEM model demonstrated the possible implementation of the induced anisotropic effects in the area of IC thermal-management.

Les travaux de cette thèse ont porté sur la conception et la réalisation d'un dispositif d'éclairage surfacique à géométrie planaire à base de structures plasmoniques, pour un fonctionnement à 633nm. Ce dispositif sera capable de convertir une lumière incidente cohérente en un faisceau de sortie uniforme sur la surface du dispositif, collimaté et avec un angle prédéfini par rapport au plan du dispositif. Pour réaliser ce dispositif, la solution envisagée est l'utilisation d'un réseau de guides d'onde diélectriques pour répartir la lumière sur la surface, et de chaînes de nano-structures d'argent couplées aux guides, dimensionnées comme des antennes pour réémettre la lumière hors du plan.Les travaux réalisés ont mis en évidence le contrôle du couplage entre le guide d'onde et la chaine de nano-structures d'argent, modulable par plusieurs paramètres dans une gamme comprise entre 10% et 90 % : nombre de particules, dimensions des particules, distance entre le guide et les particules. En jouant sur la période de la chaine, il est possible d'obtenir un rayonnement hors-plan, avec un angle déterminé par la formule des réseaux de diffraction. Des émetteurs élémentaires, composés d’un guide et de chaines de particules, ont été fabriquées en salle blanche et caractérisés sur un banc d’optique guidée à l'aide d'un montage de projection dans le plan de Fourier. Les diagrammes de rayonnement expérimentaux sont en accord avec les simulations. De premiers résultats ont également confirmé expérimentalement la possibilité de moduler le couplage guide-chaine en modifiant les dimensions des particules. Enfin le réseau de guides d'onde a été dimensionné pour une surface d'1 cm² et fabriqué en lithographie par projection. Les pertes linéiques mesurées dans les guides d'onde sont de l'ordre de 5 dB/mm. Plusieurs optimisations peuvent être réalisées pour améliorer la qualité des guides. A partir des données expérimentales obtenues et des simulations de propagation de faisceau, une configuration réaliste de dispositif d’éclairage incluant le nombre et le positionnement des émetteurs sur le réseau de guides a été proposée. L’ensemble des travaux réalisés valident l’approche choisie. / This work has focused on the design and realization of a planar lighting device based on plasmonic structures, for a 633nm operation. This device will be able to convert a coherent incident light into a uniform output beam over the surface of the device, collimated and with a predefined angle with respect to the plane of the device. To achieve this feature, the proposed solution is the use of an array of dielectric waveguides to distribute the light over the surface, and silver nanostructures chains coupled to the waveguides and dimensioned as antennas to retransmit the light out of the plane. The work carried out has highlighted the control of the coupling between the waveguide and the silver nanostructures chain, modulated by several parameters in a range between 10% and 90%: the number of particles, particle size, distance between the guide and the particles. By playing on the period of the chain, it is possible to obtain an out-of-plane radiation, with an angle determined by the diffraction gratings formula. Elementary emitters, consisting of a guide and particle chains, were manufactured in a clean room and characterized on a guided wave optical bench with Fourier plane projection set-up. The experimental radiation patterns are in agreement with the simulations one. First results have also experimentally confirmed the possibility of modulating the waveguide-chain coupling by modifying the dimensions of the particles. Finally, the waveguide network has been dimensioned for an 1 cm² surface and manufactured with projection lithography. The linear losses measured in the waveguides are of the order of 5 dB / mm. Several optimizations can be made to improve the quality of the guides. From the experimental data obtained and the beam propagation simulations, a realistic configuration of the lighting device including the number and positioning of the transmitters on the waveguide network has been proposed. All the works carried out validate the chosen approach.

Le champ biomédical n’a pas échappé à l’évolution de la technologie, elle cherche aussi à intégrer plusieurs fonctions dans un espace restreint. Un des points forts du développement est la massification de points de service, afin d'obtenir un diagnostic rapide des maladies. Le diagnostique aux premières étapes de son évolution permettra réduire considérablement les coûts associés aux traitements des patients. Le présent document exprimera une alternative à l'évolution de la technologie des biocapteurs qui sont basés sur le phénomène optique appelé résonance par plasmons de surface. Ce projet de recherche vise l’étude de l’intégration monolithique des deux tiers des composants principaux qui conforment normalement à ce type de biocapteurs optiques. Tandis que d'autres projets de recherche ont centré leurs travaux sur l’intégration de la surface de réaction et le détecteur, notre travail a pris en compte l’intégration de la source de lumière et la surface de réaction biologique. Deux types de sources ont été employés au moment de faire la conception, l’étude de matériaux, la fabrication et la caractérisation de la performance de notre dispositif. La première source a employé des puits quantiques à l’intérieur d’une gaufre de GaAs qui nécessitait un pompage optique pour son fonctionnement. La deuxième source a eu une gaufre commerciale employée pour la fabrication des diodes d’émission lumineuse verticale, qui a dû être excitée par un courant électrique. On a découvert que les deux types de sources sont complémentaires. La source avec des puits quantiques a démontré une amélioration de la performance en comparaison à notre système commercial de référence. La deuxième source a démontré la faisabilité d’intégration monolithique en permettant se rapprocher à la fabrication d’un prototype commercial. La porte reste donc ouverte pour la poursuite du développement de cette technologie en cherchant un nouveau système employant ces deux sources, mais usant de meilleures caractéristiques.

The following dissertation addresses the study of nano-magnetic devices configured to produce logic machines through magnetostatic coupling interactions. The ability for single domain magnets to reliably couple through magnetostatic interactions is essential to the proper functionality of Magnetic Cellular Automata (MCA) devices (p. 36). It was significant to explore how fabrication defects affected the coupling reliability of MCA architectures. Both ferromagnetic and anti-ferromagnetic coupling architectures were found to be robust to common fabrication defects. Experiments also verified the functionality of the previously reported MCA majority gate [1] and a novel implementation of a ferromagnetic MCA majority gate is reported. From these results, the study of clocking Magnetic Cellular Automata (MCA) interconnect architectures was investigated (p. 54). The wire architectures were saturated under distinct directions of an external magnetic field. The experimental results suggested ferromagnetic coupled wires were able to mitigate magnetic frustrations better than anti-ferromagnetic coupled wires. Simulations were also implemented supporting the experimental results. Ferromagnetic wires were found to operate more reliably and will likely be the primary interconnects for MCA. The first design and implementation of a coplanar cross wire system for MCA was constructed which consisted of orthogonal ferromagnetic coupled wires (p. 68). Simulations were implemented of a simple crossing wire junction to analyze micro-magnetic dynamics, data propagation, and associated energy states. Furthermore, two systems were physically realized; the first system consisted of two coplanar crossing wires and the second was a more complex system consisting of over 120 nano-magnetic cells. By demonstrating the combination of all the possible logic states of the first system and the low ground state achieved by the second system, the data suggested coplanar cross wire systems would indeed be a viable architecture in MCA technology. Finally, ongoing research of an unconventional method for image processing using nano-magnetic field-based computation is presented (p. 79). In magnetic field-based computing (MFC), nano-disks were mapped to low level segments of an image, and the magnetostatic coupling of magnetic dipole moments was directly related to the saliency of a low level segment for grouping. A proof of concept model for two MFC systems was implemented. Details such as the importance of fabricating circular nano-magnetic cells to mitigate shape anisotropy, experimental coupling analysis via Magnetic Force Microscopy, and current results from a complex MFC system is outlined.