Resumo: Vitrocerâmicas transparentes baseadas em novas composições de calco-halogenetos dopadas com íons de terras raras foram produzidas com o objetivo de gerar luz no visível. A adição de diferentes halogenetos alcalinos em vidros do sistema Ga2S3-GeS2 foi estudada com a finalidade de aumentar a sua janela de transparência no ultravioleta. Vidros no sistema Ga2S3- GeS2-CsCl totalmente transparentes no visível (400-750 nm) até a região do infravermelho médio (11,5μm) foram obtidos. Vitrocerâmicas transparentes e homogêneas foram em seguida preparadas a partir de vidros variando a concentração de CsCl no sistema Ga2S3-GeS2-CsCl. As condições dos tratamentos térmicos (temperaturas e tempos) foram estabelecidas permitindo o controle dos processos de nucleação e crescimento dos cristalitos dentro da matriz vítrea. Nanocristalitos uniformemente distribuídos e com tamanho homogêneo foram obtidos e confirmados por microscopia eletrônica de varredura (MEV) e microscopia eletrônica de transmissão (MET). Estudos estruturais foram realizadas nas vitrocerâmicas utilizando-se as técnicas de difração de raios X e resonância magnetica nuclear do sólido do 133Cs e 71Ga. Foi evidenciado o papel do agente de nucleação do gálio neste material, com a cristalização da fase Ga2S3. Um aumento da resistência mecânica foi também observado nestes materiais em comparação aos vidros de base. Em seguida, vitrocerâmicas dopadas com íons de terras raras (praseodímio Pr3+ e neodímio Nd3+) foram sintetizadas no sistema Ga2S3-GeS2-CsCl. A luminescência dos íons Pr3+ e Nd3+ no visível foi estudada em função dos tratamentos térmicos aplicados aos materiais. Foi observado que não houve a incorporação dos íons Pr3+na matriz. Por outro lado, um aumento da fluorescência do íon Nd3+ foi observado, sugerindo uma incorporação parcial destes íons dentro da fase cristalina... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present work deals with the study of new chalco-halide glass-ceramics doped with rare earth ions for visible luminescence. The effect of the addition of different alkali-halide into glasses belonging to the Ga2S3-GeS2 system has been studied with the aim to extend their transparency into the ultraviolet region. Glasses transparent over the visible range (400-750 nm) up to the mid infrared (11,5 μm) have been obtained in the Ga2S3-GeS2-CsCl system. Transparent and homogeneous glass-ceramics have been prepared from several base glasses varying the CsCl content in the Ga2S3-GeS2-CsCl system. Nanocrystals with homogeneous size and uniformly distributed in the amorphous matrix have been generated with reproducibility by appropriate heat-treatment. A structural study of the crystallization has been realized using X-ray diffraction and solid state nuclear magnetic resonance performed on the 71Ga and 133Cs nuclei. The nucleating agent character of gallium has been shown in the glassy matrix with the crystallization of the Ga2S3 phase. An improved mechanical behaviour has also been observed in the prepared composite materials. Rare-earth ion (praseodymium Pr3+ and neodymium Nd3+) doped glass-ceramics have been synthesized in the Ga2S3-GeS2-CsCl system. The visible luminescence from Pr3+ and Nd3+ ions has been studied as a function of heat-treatment conditions. It appeared from experiments that Pr3+ ions are not incorporated into the crystals contrary to the Nd3+ ions from which an enhanced luminescence was observed, suggesting their partial integration into the crystalline phase. Finally, silver and Pr3+ doped glasses have been synthesized in the Ga2S3-GeS2 system. Metallic silver nanoparticles were generated by heat-treatment at 370°C and characterized by transmission electronic microscopy. The influence of the NPs on the Pr3+ ions luminescence properties was studied by performing frequency... (Complete abstract click electronic access below) / Résumé: Les travaux présentés dans ce manuscrit concernent l'étude de nouvelles vitrocéramiques transparentes à base de chalco-halogénures dopées par des ions de terres pour la luminescence dans le visible. L'addition de différents halogénures d'alcalins à des verres du système Ga2S3-GeS2 a été étudiée avec l'objectif d'étendre leur transparence vers l'ultraviolet. Des verres du système Ga2S3- GeS2-CsCl complètement transparents dans le visible (400-750 nm) jusqu'au moyen infrarouge (11,5 μm) ont été obtenus. Des vitrocéramiques transparentes et homogènes ont ensuite été préparées de manière contrôlée à partir de plusieurs verres à différentes teneurs en CsCl dans le système Ga2S3-GeS2-CsCl. Des nanocristallites de taille homogène et uniformément dispersées dans la matrice amorphe sont formées de manière reproductible par des traitements thermiques appropriés. Une étude d'un point de vue structural de la cristallisation a été réalisée par diffraction de rayons X et résonance magnétique nucléaire à l'état solide sur les noyaux 71Ga et 133Cs. Le rôle d'agent de nucléation du gallium a été mis en évidence dans cette matrice avec la cristallisation d'une phase Ga2S3. Un meilleur comportement mécanique a également été observé pour les matériaux composites préparés. Des vitrocéramiques dopées par des ions de terres rares (praséodyme Pr3+ et néodyme Nd3+) ont été synthétisées dans le système Ga2S3-GeS2-CsCl. L'évolution de la luminescence dans le visible des ions Pr3+ et Nd3+ a été étudiée en fonction des conditions de traitement thermique. Au vu des résultats obtenus, il semble que l'ion Pr3+ ne soit pas incorporé dans les cristallites. Une augmentation de la luminescence de l'ion Nd3+ a en revanche été constatée, suggérant une incorporation partielle de ces ions dans une phase cristalline... (Résumé complet accès électronique ci - dessous) / Orientador: Bruno Bureau / Coorientador: Younés Messaddeq / Coorientador: Marcel Poulain / Banca: Cid Bartolomeu de Araújo / Banca: Brigitte Boulard / Banca: X. H. Zhang / Doutor

Iu, Hei = 二維週期性金屬納米共振腔的理論研究 / 姚熙. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 89-91). / Abstracts in English and Chinese. / Iu, Hei = Er wei zhou qi xing jin shu na mi gong zhen qiang de li lun yan jiu / Yao Xi. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Introduction to Surface Plasmon Polaritons --- p.3 / Chapter 2.1 --- The Maxwell´ةs Equations --- p.3 / Chapter 2.2 --- Photonic crystals --- p.5 / Chapter 2.3 --- Modeling Metal --- p.9 / Chapter 2.4 --- Surface plasmon polarition --- p.12 / Chapter 3 --- Rectangular Cavity --- p.17 / Chapter 3.1 --- Basic simulation cell setup --- p.17 / Chapter 3.2 --- Method of mode identification --- p.18 / Chapter 3.2.1 --- Dispersion relation calculation --- p.18 / Chapter 3.2.2 --- Reflection spectra --- p.19 / Chapter 3.3 --- Results and discussions --- p.20 / Chapter 4 --- Nano-bottle cavity --- p.25 / Chapter 4.1 --- Cylindrical cavity --- p.25 / Chapter 4.1.1 --- Dispersion relations calculation --- p.25 / Chapter 4.1.2 --- Field pattern calculation --- p.29 / Chapter 4.2 --- Nano-bottle cavity --- p.46 / Chapter 4.2.1 --- The effect of the bottleneck on (0，1) mode --- p.47 / Chapter 4.2.2 --- The effect of aperture size on (0，1) mode --- p.58 / Chapter 4.2.3 --- The effect of the depth of cavities on (0，1) mode --- p.62 / Chapter 4.2.4 --- "The effect of aperture size on (-1,0) mode" --- p.63 / Chapter 4.3 --- Discussions --- p.64 / Chapter 4.4 --- Verified with experimental results --- p.68 / Chapter 5 --- Aspect ratio --- p.71 / Chapter 5.1 --- Simulation structure --- p.72 / Chapter 5.2 --- Aspect ratio S = 2 --- p.73 / Chapter 5.3 --- The effect of aspect ratio --- p.74 / Chapter 5.3.1 --- Orientation dependence of the resonant mode --- p.74 / Chapter 5.3.2 --- Excitation frequency of the resonant mode --- p.75 / Chapter 5.4 --- Field location and strength --- p.76 / Chapter 5.5 --- Discussions --- p.77 / Chapter 5.6 --- Comparison with experimental results --- p.79 / Chapter 6 --- Conclusions and future works --- p.83 / Chapter 6.1 --- A possible new mode excitation --- p.84 / Chapter 6.2 --- Cavities with aspect ratio under p-polarized light --- p.86 / Bibliography --- p.89 / Chapter A --- Computational Simulation --- p.92 / Chapter A.l --- Finite-Difference Time-Domain --- p.92 / Chapter A.2 --- Computational grid --- p.93 / Chapter A.3 --- Boundary Condition --- p.93 / Chapter A.4 --- Source --- p.94 / Chapter A.5 --- Field strength --- p.94

With the development of ultra-fast laser technology, several new imaging techniques have pushed optical resolution past the diffraction limit for traditional light-based optics. Advancements in lithography have enabled the straightforward creation of micron- and nanometer-sized optical devices. Exposing metal-dielectric structures to light can result in surface plasmon excitation and propagation along the transition interface, creating a surface plasmon polariton (SPP) response. Varying the materials or geometry of the structures, the plasmonic response can be tailored for a wide range of applications. Photoemission electron microscopy (PEEM) has been used to image excitations in micron-sized plasmonic devices. With PEEM, optical responses can be characterized in detail, aiding in the development of new types of plasmonic structures and their applications. We show here that in thin, triangular gold platelets SPPs can be excited and concentrated within specific regions of the material (thickness ~50 nm); resulting in localized photoemission in areas of high electric field intensity. In this regard, the platelets behave as receiver antennas by converting the incident light into localized excitations in specific regions of the gold platelets. The excited areas can be significantly smaller than the wavelength of the incident light (λ≤1µ). By varying the wavelength of the light, the brightness of the excited spots can be changed and by varying the polarization of the light, the brightness and position can be changed, effectively switching the photoemission on or off for a specific region within the triangular gold structure. In this work, the spatial distribution of surface plasmons and the imaging results from photoemission electron microscopy are reproduced in simulation using finite element analysis (FEA). In addition, we show that electromagnetic theory and simulation enable a detailed and quantitative analysis of the excited SPP modes, an explanation of the overall optical responses seen in PEEM images, and prediction of new results.

The optical response of metallic structures is dominated by the dynamics of their free electron plasma. Plasmonics, the area of optics specializing in the electromagnetic behavior of heterogeneous structures with metallic inclusions, is undergoing rapid development, fueled in part by recent progress in experimental fabrication techniques and novel theoretical approaches. In this thesis I outline the behavior of four plasmonic material systems, and discuss the underlying physics that governs their optical response. First, the anomalous optical properties of solution-derived percolation films are explained using scaling theory. Second, a novel technique is developed to characterize the optics of amorphous nanolaminates, leading to the creation of a meta-material with anisotropic (hyperbolic) dispersion. The properties of such materials can be tuned by adjusting their composition. Third, the electrodynamics of vertically aligned multi-walled carbon nanotubes is derived through the development of a spectroscopic terahertz transmission ellipsometry algorithm. Lastly, a new diffraction based imaging structure based on metallic gratings is presented to have resolution capabilities which far outperform the diffraction limit. / Graduation date: 2013

In this work, the structural and optical properties of metal nanoparticles fabricated on various substrates have been investigated. The particles were fabricated by electron beam lithography (EBL) and dewetting of a thin metal film. The advantages and disadvantages of these two fabrication techniques are discussed by considering the properties of the nanoparticles and the applicability to large area substrates. Being a practical fabrication method, dewetting can be applied to any substrate with either small or large surfaces. For comparison between different sample types, some process parameters such as film thickness, annealing temperature and duration were fixed during the whole study. Gold (Au) and silver (Ag) were preferred for nanoparticle formation because of their superior optical properties for solar cell applications. We used silicon (Si), silicon nitride (Si3N4), silicon dioxide (SiO2) and indium tin oxide (ITO) on glass, and textured Si as the substrate for the particle formation. These substrates are commonly used in solar cell technology for different purposes. The formation of the metal nanoparticles, their size and size distribution were monitored by Scanning Electron Microscope (SEM). We performed a dimension analysis on the SEM images using a program called Gwyddion. We observed that the substrate type greatly affects particle mean size, suggesting a dependence of the dewetting process on the interface properties. Moreover, the effect of the annealing temperature was found to be a function of the substrate type. Scattering measurements have been carried out in order to observe the localized surface plasmon resonance (LSPR) conditions. The effect of the particle size and the dielectric environment was observed as a shift in the plasmon resonance peak position along the wavelength axis. As expected from the theory, the resonance peaks shift to longer wavelengths with increasing particle size and dielectric constant. In order to compare the experimental results with the theory, Mie theory was applied to calculate the plasmon resonance peaks. We obtained fairly well agreement between the experimental and theoretical results. In this study, nanoparticles were assumed to be in contact with more than one medium, namely air and the underlying substrate. Finally, we have reached a successful methodology and knowledge accumulation for the metal particle formation on variety of substrates by the dewetting technique. It is clear that this knowledge can form basis for the photovoltaic applications.

Reproduction de : Thèse de doctorat : Milieux denses et matériaux : Poitiers : 2008. / Titre provenant de l'écran-titre. Bibliogr., 292 réf.

This thesis details original experimental investigations in to the interaction of light with the mobile electrons at the surface of metallic diffraction gratings. The gratings used in this work to support the resultant trapped surface waves (surface plasmon polaritons), may be divided into two classes: ‘crossed’ bigratings and ‘zigzag’ gratings. Crossed bigratings are composed of two diffraction gratings formed of periodic grooves in a metal surface, which are crossed at an angle relative to one another. While crossed bigratings have been studied previously, this work focuses on symmetries which have received comparatively little attention in the literature. The gratings explored in this work possesses two different underlying Bravais lattices: rectangular and oblique. Control over the surface plasmon polariton (SPP) dispersion on a rectangular bigrating is demonstrated by the deepening of one of the two constituent gratings. The resulting change in the diffraction efficiency of the surface waves leads to large SPP band-gaps in one direction across the grating, leaving the SPP propagation in the orthogonal direction largely unperturbed. This provides a mechanism to design surfaces that support highly anisotropic propagation of SPPs. SPPs on the oblique grating are found to mediate polarisation conversion of the incident light field. Additionally, the SPP band-gaps that form on such a surface are shown to not necessarily occur at the Brillouin Zone boundaries of this lattice, as the BZ boundary for an oblique lattice is not a continuous contour of high-symmetry points. The second class of diffraction grating investigated in this thesis is the new zigzag grating geometry. This grating is formed of sub-wavelength (non-diffracting) grooves that are ‘zigzagged’ along their length to provide a diffractive periodicity for visible frequency radiation. The excitation and propagation of SPPs on such gratings is investigated and found to be highly polarisation selective. The first type of zigzag grating investigated possesses a single mirror plane. SPP excitation to found to be dependant on which diffracted order of SPP is under polarised illumination. The formation of SPP band-gaps is also investigated, finding that the band-gap at the first Brillouin Zone boundary is forbidden by the grating’s symmetry. The final grating considered is a zigzag grating which possesses no mirror symmetry. Using this grating, it is demonstrated that any polarisation of incident light may resonantly drive the same SPP modes. SPP propagation on this grating is found to be forbidden in all directions for a range of frequencies, forming a full SPP band-gap.

Metallic nanostructures such as nanoparticles, nanowires and nanoapertures exhibit extraordinary optical properties in absorption, scattering and transmission of electromagnetic radiation due to the excitation of surface plasmons. This allows them to provide applications in converting photon energy to other forms of energy such as heat, mechanical work and electricity in a more efficient or controlled manner. When incorporated into an amorphous silicon thin film solar cell, nanoparticles were found to substantially increase the light absorption in the photoactive layer within certain wavelength range. The mechanism of this optical absorption was studied using three-dimensional finite element method. It was found that intensified Fabry-Perot resonance in the active layer due to the addition of the nanostructures and enhanced light scattering by the plasmonic nanostructures were both responsible for this phenomenon. Interestingly, higher absorption only occurs at wavelength range outside the surface plasmons resonance of the nanostructures. A further study on the absorption of the nanoparticles themselves revealed that enhanced near field associated with the SP resonance of particles causes extraordinary energy dissipation in the particles, resulting in decreased light scattering. Strong power dissipation accompanied with the surface plasmons resonance becomes desirable when nanostructures are used as heat generator. Using the new technique of three-dimensional localization of the metallic nanoparticles on polymer microstructures, wavelength dependent controlling of a light-driven microactuator was achieved by selectively coating it with nanoparticles of different materials. Another important plasmonic nanostructure is the subwavelength hole arrays perforated on a metal film. The optical transmission through these nanometer scaled apertures whose dimensions are smaller than the wavelength of the incident light can be several orders of magnitude larger than expected. Based on this property, a novel tandem solar cell structure was proposed. A metal film perforated with periodic subwavelength hole arrays was inserted in a tandem solar cell as a light transmittable intermediate common electrode for the top and the bottom cell. The perforated electrode removes the current matching restriction in conventional tandem cells and allows active materials with different energy conversion and charge transport mechanisms to be combined in the same device. If used in a multi-junction solar cell, the new design can also save the power loss across the tunnel junction. The perforated intermediate electrode was modeled and its optical performance in the tandem solar cell was investigated. / text

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Šiame darbe išnagrinėjome paviršines elektromagnetines bangas kairinių medžiagų sandūrose. Tyrėme, ar sandūrose tarp įprastinių aplinkų, kurių μ > 0 ir ε > 0, ir kairinių medžiagų, kurių μ < 0 ir ε < 0, gali susidaryti paviršiniai plazmonai. Įrodėme, kad, kai dviejų aplinkų magnetinės skvarbos , paviršiniai plazmonai visada susiformuoja įprastinės ir kairinės medžiagų sandūroje. Taip pat nustatėme, kad įprastinės aplinkos, kurios , ir kairinės medžiagos aplinkos, kurios , sandūroje, kai ir , gali susiformuoti paviršiniai plazmonai. Ištyrę paviršinių plazmonų susidarymo sąlygas, išanalizavome dažnines dielektrinių ir magnetinių skvarbų priklausomybes ir nustatėme, kad įprastinių aplinkų, kurių , ir kairinių medžiagų aplinkų, kurių , sandūrose paviršiniai plazmonai susidaro, kai metamedžiagų dažniai yra rezonansinių dažnių eilės. / Dielectric materials are characterized by two parameters, magnetic permeability and electric permittivity determining its responseto the electromagnetic radiation. A left-handed material is a material whose permeability and permittivity are simultaneously negative, μ < 0 and ε < 0. Such a material can be a structure composed of metal split ring resonators and rods that causes microwaves to behave in an unusual manner. A left-handed material reverses a basic feature of light. Specifically the phase of the electromagnetic wave propagates in the opposite direction to the energy flow leading to the negative refraction. A possible application of the left-handed materials was suggested in 2000 by Pendry, who considered the optical properties of a rectangular lens made of a slab of negatively refracting material. Some of the radiation waves emitted or reflected by ordinary objects decay very quickly. As a result, the subwave length structural information about the object carried by these ‘evanescent’ waves is lost. Left-handed materials would amplify evanescent wave thus retaining the information they contain and achieving unprecedented resolution that overcomes diffraction limit of conventional imaging. The aim of this work is to analyse the formation of the surface plasmons at an interface between an ordinary material and a metamaterial characterized by negative electric polarisability and negative magnetic permeability. For this purpose we have first analyzed the boundary... [to full text]