Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [89]-102).

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references (leaves 96-102). Issued in print and online. Available via ProQuest Digital Dissertations.

L'importance du traitement du signal et la transmission favorise de nouvelles applications pour les matériaux optiques non linéaires, tels que des convertisseurs de fréquence. Les cristaux sont des matériaux pour ces applications bien connues en raison de leur comportement non linéaire optique forte. Cependant, ils sont coûteux à fabriquer et dépendent fortement de l'orientation cristalline. Les verres sont des candidats possibles à cause de leurs propriétés optiques et la facilité de fabrication, mais ils ne possèdent pas de second ordre non-linéarité en raison de leur structure centrosymétrique. Cependant, un matériau composite vitrocéramique avec des cristaux ferro-électriques noyées dans une matrice de verre peut combiner les propriétés de cristaux non linéaires avec la facilité de fabrication de lunettes.Germanotellurite verre et la céramique, verre dopés avec différentes quantités d'oxyde d'argent, dans la (100-x) (70TeO2 - 10GeO2 - 10Nb2O5 - 10 - K2O) xAg2O système (x = 0 à 6% en mole), a été étudiée. L'étude se compose de l'élaboration et la caractérisation d'une céramique de verre qui peuvent répondre aux exigences de matériaux optiques non linéaires, avec une grande transparence et une activité non linéaire intense. Les caractéristiques des verres et de la céramique de verre ont été déterminées par analyse thermique, diffraction des rayons X, la microscopie électronique, UV-Vis et spectroscopie Raman. Cristallisation en vrac a été observé pour les verres d'argent dopé avec une phase cristalline unique (Ag, K) [Nb1 / 3Te2 / 3] 2O4.8, qui présente une activité seconde génération harmonique (SHG). Un seul traitement thermique a abouti transparence supérieure à un traitement thermique en 2 étapes avec un premier chauffage à la température de nucléation et un second traitement pour la croissance cristalline. Pour les modes de transmission et XRD UV-Vis similaires, les échantillons de chaleur 1-étape traités ont montré une réponse SHG deux ordres supérieur à la 2-étape.Cette différence d'intensité provient de la taille des domaines à l'intérieur des deux céramiques de verre. Le traitement thermique une étape a été trouvé, de promouvoir micron de taille domaines cristallisés, alors que le traitement thermique en deux étapes a abouti à des tailles de sous-domaine de longueurs d'onde. La réponse macroscopique SHG global a été trouvé pour présenter le comportement dipolaire typique. Ce dipôle nature vient de chaque domaine agissant comme SHG émetteur. Une caractérisation basée sur une technique de micro-Raman / micro-SHG corrélative, qui peut fournir à la fois des informations structurelles et les réponses de SHG locales dans les mêmes régions sub-micron, a été réalisée, ce qui indique que l'organisation de cristallites dans les domaines rend leur réponse SHG indépendante de polarisation de la lumière. Un modèle structural a été proposé pour expliquer la propriété dipolaire général et l'indépendance de la polarisation de la lumière. / The importance of signal processing and transmission promotes new applications for nonlinear optical materials, such as frequency converters. Crystals are well known materials for these applications because of their strong optical nonlinear behaviour. However, they are costly to manufacture and are strongly dependant on crystal orientation. Glasses are possible candidates because of their optical properties and ease of fabrication but they possess no second-order nonlinearity due to their centrosymmetric structure. However, a glass-ceramic composite with ferroelectric crystals embedded in a glass matrix can combine the nonlinear properties of crystals with the easiness of fabrication of glasses.Germanotellurite glass and glass ceramics, doped with different amounts of silver oxide, in the (100-x)(70TeO2 – 10GeO2 – 10Nb2O5 – 10 K2O) – xAg2O (x=0-6 mol%) system, has been studied. The study consists of elaboration and characterization of a glass ceramic that can fulfil the requirements of nonlinear optical materials, with high transparency and intense nonlinear activity. The characteristics of the glasses and glass ceramics were determined by thermal analysis, X-ray diffraction, electron microscopy, UV-Vis and Raman spectroscopies. Bulk crystallization has been observed for the silver-doped glasses with a unique crystal phase, (Ag,K)[Nb1/3Te2/3]2O4.8, which presents second harmonic generation (SHG) activity. A single heat treatment yielded higher transparency than a 2-step heat treatment with a first heating at the nucleation temperature and a second treatment for crystal growth. For similar UV-Vis transmission and XRD patterns, the 1-step heat treated samples showed a two order higher SHG response than the 2-step one.This intensity difference comes from the size of domains within the two glass ceramics. The 1-step heat treatment was found to promote micron sized crystallized domains, while the two step heat treatment yielded sub-wavelength domain sizes. The global SHG macroscopic response was found to present typical dipolar behaviour. This dipole nature comes from each domain acting as SHG emitter. A characterization based on a correlative micro-Raman/micro-SHG technique, which can provide both structural information and local SHG responses within the same sub-micron areas, was performed, indicating that the organization of crystallites inside the domains makes their SHG response independent of light polarization. A structural model has been proposed to explain the general dipolar property and the light polarization independence.

Apresentamos os resultados de preparação e caracterização de cristais orgânicos (L-arginina fosfatada monohidratada - LAP - e L-lisina monohidroclorada dihidratada - L-Lys.HCl) que possuem propriedades ópticas lineares e não lineares desejáveis para aplicações tecnológicas, incluindo telecomunicações, computação óptica, armazenamento óptico de dados, processamento óptico da imagem, conversão de freqüência, entre outras. Desenvolvemos uma metodologia, simples e barata, para a eliminação de fungos e micróbios que surgem nas soluções destes compostos devido às características dos aminoácidos L-arginina e L-lisina. A adição do fungicida azida de sódio possibilitou-nos manter soluções destes compostos livres de quaisquer microorganismos na câmara de crescimento por um período de seis meses. Usando-se as técnicas de evaporação controlada do solvente a abaixamento da temperatura grandes cristais de LAP e L-Lys.HCl foram obtidos com qualidade óptica adequada para a confecção de dispositivos optoeletrônicos. Cristais de até 6 cm&sup3 de L-Lys.HCl foram pela primeira vez preparados e caracterizados opticamente. A caracterização estrutural permitiu-nos solucionar a divergência existente na indexação do difratograma de pó dos cristais de LAP e indexar os picos de difração de raios-X da L-lisina monohidroclorada dihidratada. / Growth and characterization of organic crystal (L-arginine phosphate monohydrate - LAP - and L-lysine monohydrochloride dihydrate L-Lys. HCl) with desirable linear and nonlinear optical properties for technological application including telecommunications, optical computing, optical data storage, optical image processing, harmonic frequency generation, and others are presented. We developed a simple and cheap method to eliminate fungi and microbes that arises in solution due to characteristics of L-arginine and L-lysine aminoacids. The addition of sodium azide fungicide maintained the solutions of these compounds free of microorganisms in the growth chamber for six months. Using a accurately controlled solvent evaporation technique and slow cooling technique large crystals of LAP and L-Lys.HCI were obtained with optical quality appropriate to the development of optoelectronic devices. L-Lys.HCl crystals up to 6 cm&sup3 were growth and optically characterized for the first time. The divergence in the powder diffraction indexation of LAP crystals was eliminated by structural characterization and the X-ray diffraction peaks of the L-lysine monohydrochloride diliydrate crystals were indexed.

Orientador: Luis Eduardo Evangelista de Araujo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-17T12:16:24Z (GMT). No. of bitstreams: 1 FernandezApolinario_Ulices_M.pdf: 3294486 bytes, checksum: d7134abb4e7c7345ce3358e57af0e8db (MD5) Previous issue date: 2010 / Resumo: Nesta tese, descrevemos o desenvolvimento de um sistema laser simplificado que opera em 423 nm (baseado em um laser de diodo) e a construção de uma célula de vapor de cálcio com potencial uso em espectroscopia de alta resolução. Nosso trabalho começou com a construção de um laser de diodo em cavidade estendida operando em 846 nm e com uma potência útil de 158 mW que foi montado em configuração Littrow. Em seguida, foi duplicada a freqüência deste laser para 423 nm através de um cristal BIBO (BiB3O6), utilizado dentro de uma cavidade óptica de amplificação. A estabilização da cavidade óptica duplicadora de freqüência foi feita pela técnica de Hänsch-Couillaud para travar uma ressonância da cavidade ao laser infravermelho de entrada. Um máximo de potência de 20 mW no azul foi obtido, mas problemas relacionados ao travamento da cavidade duplicadora dificultam seu uso. Por isto, um segundo laser de diodo em cavidade estendia, similar ao anterior, mas com uma potência útil de 75 mW, foi usado com uma potência máxima de 4 mW no azul e apresentado similares dificuldades ao sistema desenvolvido anteriormente. Uma célula de vapor de cálcio foi construída tendo como fonte de átomos de cálcio um dispensador ¿Alvasource¿ da empresa ¿Alvatec¿. Uma primeira caracterização da célula através de espectroscopia de absorção foi realizada demonstrando seu potencial uso para experimentos em Física Atômica / Abstract: In this thesis, we describe the development of a simplified laser system that operates at 423 nm (based on a diode laser) and the construction of calcium vapor cell with potential use in high resolution spectroscopy. Our work began with the construction of a extended-cavity diode laser operating at 846 nm with an output of 158 mW that was mounted in Littrow configuration. Then, the laser¿s frequency was doubled to 423 nm through a BIBO (BiB3O6) crystal used within a power enhancement cavity. The stabilization of the frequency doubling cavity was made by Hänsch-Couillaud technique to lock a cavity resonance to the input infrared laser. A maximum power of 20 mW was obtained in the blue, but problems related to locking the doubling cavity hamper its use. Therefore, a second extended-cavity diode laser, similar to the above but with an output of 75 mW was tried, reaching a maximum power of 4 mW in the blue. However, it presented similar difficulties to the system developed earlier. A calcium vapor cell was constructed based on Ca ¿Alvasource¿ dispenser by ¿Alvatec¿. A first characterization of the cell by absorption spectroscopy was performed demonstrating its potential use for experiments in atomic physics / Mestrado / Ótica / Mestre em Física

Neste trabalho é feito um estudo da formatação de pulsos ultracurtos de laser de Ti:Safira para a geração de segundo harmônico em cristal de KDP. Para a formatação dos pulsos, é utilizado um aparato que inclui um modulador espacial de luz de cristal líquido (LC SLM), que altera unicamente a fase espectral dos pulsos. Este aparelho tem a vantagem de não introduzir perdas durante a propagação da luz, além de sua ação ser controlada via computador, através de um software em LabVIEW. Utilizando uma função senoidal, é feito um estudo das limitações do controle da geração do segundo harmônico provindas da pixelação do LC SLM, isto é, do fato de que os elementos moduladores possuem tamanhos finitos e produzem uma modulação discreta ao longo das componentes espectrais do pulso. É apresentada a geração de luz sintonizável em torno de 400 nm por duplicação de frequências de pulsos cuja fase espectral é modulada por uma soma de funções senoidais de frequências diferentes. A largura de banda do ultravioleta produzido é da ordem de 1 nm, em contraste com a largura de linha de cerca de 12 nm do segundo harmônico gerado na ausência de modulação do pulso fundamental. A sintonização é feita basicamente através de uma varredura na fase das funções moduladoras do pulso fundamental. Esse tipo de sintonização nessa região do espectro possui algumas aplicações, tais como a microscopia seletiva por dois fótons ou mesmo a espectroscopia de um fóton. Para comprovar a utilidade da geração de segundo harmônico sintonizável, é apresentada uma medida espectroscópica da transmissão em uma amostra de cloreto de európio, sendo que os resultados obtidos concordaram com as medidas da mesma amostra realizadas em um espectrofotômetro, com o mínimo de transmissão em cerca de 394 nm. / This work presents a study on the shaping of ultrashort pulses of a Ti:Sapphire laser for second harmonic generation in KDP crystals. To achieve the pulse shaping, a setup based on a phase-only crystal-based spatial light modulator (LC SLM) is used. This device has the advantage of low loss, and can be computer controlled, by means of a LabVIEW software. The use of a sinusoidal function, allows to study the limitations of the second harmonic generation due to the pixelation of the LC SLM, i. e., due to the fact that the modulating elements have finite sizes and produce a stepwise modulation along the spectral components of the pulse. The generation of tunable light around 400 nm by frequency doubling of laser pulses is presented for the case where the spectral phase is modulated by a sum of sinusoidal functions with different frequencies. The linewidth of the ultraviolet band produced is narrower than 1 nm, in contrast to the 12 nm linewidth of the non-modulated incident spectrum. The tuning is done primarily through a sweep in the phase of the modulating functions of the fundamental pulse. The possibility of tuning in this region of the spectrum has a few applications, such as in selective two-photon microscopy or even in one photon spectroscopy. To demonstrate the usefulness of tunable second harmonic generation, a spectroscopic measurement of the transmission in a sample of europium chloride is presented, and the results agreed with the measures of those performed in a spectrophotometer, with the minimal transmission occurring around 394 nm.

La thèse montre des solutions pour la réalisation de circuits photoniques intégrés utilisant le caractère volumétrique et les très faibles pertes en propagation des solitons spatiaux. On s'intéresse aux éléments de base : interconnexions, sources et router optique (comme dispositif d'élaboration). Interconnexions et sources sont réalisé dans le niobate de lithium (LN) qui fournis des structures avec une très longue durée temporelle. Le fonctionnement d'un router optique est démontré dans le semiconducteur photo-réactif (PR) InP:Fe en raison de sa sensitivité aux longueurs d'onde infrarouges (IR) et à son temps de réponse rapide. On montre que les pertes en propagation dans les interconnexions solitoniques peuvent être réduites à nouveau en utilisant un faisceau en polarisation ordinaire qui augmente la variation d'indice de réfraction induite. La réalisation de sources intégrées solitoniques est étudié pour avoir émission en bleu à 400nm et en IR à 1530nm. Celles en bleu sont obtenues par génération de deuxième harmonique ; le rôle du bleu pour la formation des solitons est montré et ses propriétés physiques étudiées. Celles en IR sont obtenues en dopant le LN avec des ions (actifs) d'erbium. Leurs effets sur les paramètres PR sont présentés et les solitons spatiaux sont obtenus en excitant l'absorption soit du LN soit de l'erbium. L'amplification de la luminescence est étudié numériquement. Le routage optique dans le InP:Fe est obtenu en faisant interagir deux solitons cohérents et en changeant leur phase relative. L'augmentation de la séparation ou leur fusion est analysé en fonction de la distance entre eux, température et intensité de la lumière / Solutions for the realization of integrated photonic circuits with the advantages that spatial solitons offer, like their volumetric nature and the very low propagation losses are shown. Interconnections, sources and optical router (as signal elaboration device) are investigated. Interconnections and sources are experimentally demonstrated in lithium niobate (LN) that provides long-lasting structures thanks to its very long dielectric relaxation time. The optical router working principle is realized in the photorefractive semiconductor InP:Fe because of its sensitivity in infrared radiation and its fast response time. To improve solitonic interconnections, an analysis based on propagation losses in function of light polarization and LN anisotropy is done. The key role played by an ordinary polarized beam on the induced refractive index variation is exploited. Integrated sources in solitonic waveguides for the emission of blue at 400nm and of an infrared beam at 1530nm are investigated. Sources emitting in blue are obtained via a second harmonic generation process ; blue seed role in spatial soliton formation is demonstrated and its physical properties are investigated as well. The infrared one is achieved by doping LN with (active) erbium ions. Their effects on the photorefractive parameters are exploited and spatial solitons realized both pumping direcly erbium absorption lines and the LN ones. Luminescence amplification is studied numerically. Optical routing in InP:Fe is achieved by making two coherent solitons interact by changing their relative phase. Separation increasing or fusion is analyzed in function of mutual distance, temperature and light intensity

La maladie carieuse a pour conséquence la déminéralisation de l’émail et de la dentine et la dénaturation du collagène de la dentine. En combinant la microscopie et spectroscopie multiphotoniques, nous avons démontré que l’intensité de la fluorescence (2-Photon Excited Fluorescence = 2PEF) et de la seconde harmonique (Second Harmonic Generation = SHG) de la dentine sont fortement modifiées pendant le processus carieux et nous avons découvert que le ratio SHG/2PEF est un paramètre fiable pour suivre le processus carieux. À présent nous souhaitons évaluer la sensibilité de la méthode en déterminant les limites des signaux mesurés pour détecter les premiers stades de la lésion carieuse. Nous avons noté une modification des spectres 2PEF de l’émail (à partir d’ICDAS (International Caries Detection and Assessment System) 1) et une modification des spectres 2PEF et SHG de la dentine (à partir d’ICDAS 2) dès les premiers stades du processus carieux. Nous avons également l’intention d’étudier la modification de la structure de la dentine lors du processus carieux grâce à la variation du signal de la SHG ; et plus précisément la (ou les) causes du « shift » vers le rouge du spectre de 2PEF observé lors du processus carieux. L’objectif serait une future application de ces signaux optiques dans le diagnostic clinique cariologique. / Multiphoton microscopy and nonlinear spectroscopy is used to investigate caries process in dentin. Though a major calcified tissue of the teeth, the organic dentin phase comprises type I collagen fibers. Caries drive both dentin demineralization and collagen denaturation. Multiphoton microscopy is a powerful imaging technique because the biological materials are transparent to infrared frequencies and can be excited to penetration depths inaccessible to one photon confocal microscopy. The laser excitation greatly reduces photodamage to the sole focal region, and the signal to noise ratio is improved significantly. The method has been used to follow pathological processes involving collagen fibrosis or collagen destruction based on their 2-photon excited fluorescence (2PEF) emission and second harmonic generation (SHG). Combining multiphoton imaging with nonlinear spectroscopy we demonstrate that both 2PEF and SHG intensity of human dentin are strongly modified during tooth caries process and we discover that the ratio between SHG and 2PEF signals is a reliable parameter to follow dental caries. The ratio of the SHG/2PEF signals measured by nonlinear optical spectroscopy provides valuable information on caries process, specifically on the degradation of the organic matrix of dentin. The goal would be to bring these nonlinear optical signals to clinical application for caries diagnosis.

Much of the interest in bent-core compounds in the last few years has centred aroundtheir potential to form nematic liquid crystal phases, which may be both biaxial andpolar. These properties offer possibilities for nematic ferroelectric switching andnonlinear optics applications. In this work, two optical properties, the refractive indices and the second ordernonlinear optical response, were investigated in the high temperature (> 170 °C)nematic phase of a series of bent-core oxadiazole compounds, of varying chain typeand length. An experimental technique, based on the acquisition and analysis of reflectionspectra from liquid crystal cells, and capable of operating at the high temperaturesrequired, was used for the measurement of refractive indices. The extraordinaryrefractive index was found to range from 1.70 to 1.78 over the nematic phase of thebent-core compounds. The ordinary refractive index varied from 1.58 to 1.62. Bothranges of values are higher than is typically observed for rod-like liquid crystals. Thebirefringence took values from ~ 0.10, in the high temperature nematic phase, to~ 0.18, close to the underlying smectic phase. A new experiment was designed, constructed and tested for the second harmonic(SH) measurements. The dependences of the SH on temperature and on scatteringangle are well explained by the theory of SH generation by the flexoelectricpolarisation induced by thermal fluctuations of the director in the nematic phase. Themaximum conversion efficiency was measured to be very low, ~ 1/10000 of apercent. No evidence for the formation of macroscopic biaxial nematic phases was found byeither the refractive indices or SH experiments. However, for the compounds havinglong nematic phases of > 50 °C, different regimes of behaviour in the uniaxialnematic phase were revealed by the SH experiments. This atypical behaviour isconsistent with other reports on these compounds. This study cannot confirm the existence of nanoscale cybotactic clusters in thenematic phases of the bent-core compounds examined but neither is it inconsistentwith them.

The evolution of electronics has become the staple thrust of modern scientific innovation: a need for advancing materials engineered for our equally rapidly advancing needs and computing requirements has fueled recent wealth of new materials. Here, I use the ideals of exotic materials design to answer this need, specifically for 2D materials. Two-dimensional (2D) van der Waals materials with in-plane anisotropy are of great interest for directional transport of charge and energy. I perform solid state synthesis to produce several such materials: an intrinsic antiferromagnet, superatomic semiconductors, and a polytype system with a component that displays the possibilities of Weyl nodes.The former, chromium sulfur bromide (CrSBr), is first synthesized, then fully studied structurally, compositionally, electronically, and magnetically. Second harmonic generation (SHG), more advanced than older techniques such as magneto-optical Kerr spectroscopy or Raman spectroscopy, allows us to fully understand the magnetic symmetry in this system as an interlayer antiferromagnetic and intralayer ferromagnetic in-plane anisotropic material. I also introduce published work in which we integrate CrSBr into different devices to show the utility of this fundamental research into a more practical application setting. It is used to stimulate more magnetic response from graphene — promising ultra-thin magnetic memory or sensory devices in future projects. Applying strain and external magnetic fields provides another tuning knob through which to access different functional modalities. In the latter third of this dissertation, we report a layered van der Waals semiconductor with in-plane anisotropy built upon the superatomic units of Mo₆S₃Br₆ (MSB), a robust construction with a direct gap of 1.64 eV. Next, MSB and Re₆Se₈Cl₂, another analogous superatomic vdW material, are potential candidates for optoelectronic applications; we qualify this by studying their Auger dynamics as a measure of quantum efficiency. Finally, layered van der Waals (vdW) materials belonging to the MM’Te₄ structure class have recently received intense attention due to their ability to host exotic electronic transport phenomena, such as in-plane transport anisotropy, Weyl nodes, and superconductivity. In summary, we have discovered two ternary exfoliatable vdW TMD polytypes with the composition TaFeTe₄, one of which (ꞵ) shows the prerequisite symmetry elements to be a type-II Weyl semimetal. This dissertation is a treatise to solid state synthesis, exploration into the more exotic spectrum of 2D materials, and robust and eclectic methods used to paint a full picture of different magnetic and electronic systems within.