Orientadores: Hugo Enrique Hernandez Figueroa, Gilberto Medeiros Ribeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e da Computação / Made available in DSpace on 2018-08-05T03:16:18Z (GMT). No. of bitstreams: 1 Sousa_AntonioCarlosTorrezande_M.pdf: 2536341 bytes, checksum: 2f6ebfc74e6b1e0305c7887d30758ce9 (MD5) Previous issue date: 2005 / Resumo: O objetivo deste trabalho é construir uma instrumentação que permita a realização de ressonância de spin eletrônico (ESR) em amostras com baixo número de spins, como, por exemplo, pontos quânticos (QDs) auto-formados de InAs. Para isto, este trabalho se propõe em usar cavidades de microfita (MRs). Apesar do seu baixo fator de qualidade, MRs apresentam um alto fator de preenchimento, parâmetro diretamente relacionado com a sensibilidade. Assim, ao analisar como cada dimensão da cavidade influencia na sensibilidade e tendo em mente os outros requisitos da ESR a serem satisfeitos, a geometria final de uma cavidade em GaAs pode ser determinada. Fora a cavidade, todas as transições presentes no sistema foram avaliadas. Por fim, diversos sistemas de detecção foram testados e comprovaram a funcionalidade do sistema montado, completando a análise de todos os elementos de um espectrômetro de ESR / Abstract: The goal of this work is to build an electron-spin resonance (ESR) spectrometer with enhanced sensitivity in order to allow the measurement of samples with a small number of spins such as InAs self-assembled quantum dots (QDs). Here, it is proposed the use of microstrip resonators (MRs) to achieve this goal. Despite of its low quality factor, MRs have a very large filling factor, which boosts the signal-to-noise ratio (SNR) of the system. This way, the final geometry of a MR built on GaAs substrate was determined after fulfilling the requirements from the sensitivity as well as from the ESR. Besides that, all the transitions present in the system were assessed. By the end, some detection systems were tested and proved the working of the system built, completing the analysis of all the elements of a spectrometer / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Made available in DSpace on 2014-10-09T12:45:36Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:38Z (GMT). No. of bitstreams: 1 07309.pdf: 6512485 bytes, checksum: da19e05a16a320b11188314140f1865c (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

O incessante aumento do volume de informações produzido por uma sociedade cada vez mais informatizada tem elevado drasticamente os requisitos quanto ao desenvolvimento de dispositivos capazes de suportar velocidades de operação cada vez mais elevadas em tamanhos cada vez mais reduzidos. No entanto, a contínua redução do tamanho desses dispositivos, celebrado através da lei de Moore, também produz um indesejável aumento na produção de calor durante a operação dos mesmos, comprometendo seu desempenho global. Uma alternativa promissora para aliviar, ou mesmo superar, estas limitações é oferecida pelos dispositivos ópticos integrados. No entanto, todo esse avanço esbarrava no fato de que as dimensões de tais dispositivos estavam restringidas fundamentalmente ao que é largamente conhecido como limite de difração (LD). Uma maneira de contornar essa limitação é obtida através da utilização de Plásmon Poláritons de Superfície, ou SPPs, que, de maneira simplificada, são ondas que se propagam ao longo da superfície de um condutor depositado sobre um dielétrico. Estas são essencialmente ondas de luz que são localizadas na superfície por causa de sua interação com os elétrons livres do condutor. Nesta interação, os elétrons livres respondem coletivamente oscilando em ressonância com a onda de luz. No presente trabalho, o fenômeno de geração de SPPs é estudado teoricamente e aplicado na modelagem de diversas estruturas de interesse científico e tecnológico, tais como acopladores direcionais e ressoadores. O objetivo principal é a obtenção de estruturas capazes de proporcionar propagação de SPPs por longas distâncias, permitindo, assim, estender ainda mais o leque de possíveis aplicações. As estruturas são investigadas prioritariamente no COMSOL Multiphysics, um aplicativo baseado em elementos finitos que permite solução vetorial de problemas eletromagnéticos. Os resultados obtidos até o momento permitem afirmar que o conceito de SPP de longa distância (long range SPP, LRSPP) podem ser aplicados com sucesso a estruturas geometricamente complexas como os ressoadores em anel e acopladores direcionais. / The continuous growth of knowledge produced by a society with increasing access to information technologies has demanded the development of communication devices capable of supporting high processing speeds at more and more reduced sizes. Nevertheless, the continuous reduction of the size of these devices, celebrated by the Moore\'s law, has also produced an undesirable increase of heat produced during the operation of the device itself, compromising its overall performance. A promising alternative to alleviate, or even overcome, these limitations has been offered by photonic integrated circuits. However, all the advance of photonic devices was restricted to what is known as diffraction limit. A fascinating way of circumventing this limit is now available to the scientific community, and consists in the generation of Surface Plasmon Polariton (SPP) waves. In a simplified manner, SPP waves are waves that propagate along a metal/dielectric interface. These waves are essentially localized at the metal/dielectric interface because of the interaction of light with free electrons of the metal. In this interaction, the free electrons respond collectively and oscillate resonantly with the incident light. In the present work, the phenomenon of SPP generation is theoretically investigated and applied to the modeling of several structures, such as directional couplers and resonators. The primary goal of this work is to design structures capable propagating SPP waves for long distances, known as long range SPP (LRSPP). The structures are investigated mostly with COMSOL Multiphysics, a finite elements based software that allows for the vectorial solution of electromagnetic problems. The results obtained so far are extremely encouraging, and prove that the LRSPP concept can be successfully applied to geometrically complex structures, such as couplers and ring resonators.

Le contrôle des ondes électromagnétiques joue un rôle fondamental dans les technologies photoniques actuelles. De nos jours, on assiste à une demande croissante de composants agiles capable d'absorber efficacement les ondes électromagnétiques dans divers gamme de fréquences. Habituellement, ces absorbeurs s'appuient sur les résonances plasmoniques qui apparaissent dans les métaux nobles dans la gamme visible. Cependant, l'extension des propriétés plasmoniques aux spectres infrarouge et THz nécessite des matériaux adéquats ayant un comportement métallique à ces fréquences. Dans ce travail, nous étudions numériquement et expérimentalement les structures métal-isolant-métal (MIM) réalisées à partir de semi-conducteur hautement dopé Si: InAsSb qui a un comportement métallique dans la gamme infrarouge. Dans la deuxième partie, nous avons amélioré l'efficacité des résonateurs MIM en utilisant des métamatériaux hyperboliques qui miniaturisent les résonateurs. Dans la dernière partie, nous proposons un design universel ultra-mince qui permet de dépasser les contraintes associées au choix des matériaux et permettant la réalisation d'un absorbeur fonctionnant sur une gamme spectrale allant de l'infrarouge aux micro-onde. / The control of light absorbance plays a fundamental role in today's photonic technologies. And the urge to design and develop flexible structures that can absorb electromagnetic waves is very growing these days. Usually, these absorbers relies on plasmonic resonances that arise in noble metals in the visible range. However, the extension of the plasmonic properties to the infrared and THz spectra requires adequate materials that have a metallic behavior at these frequencies. In this work, we study numerically and experimentally the metal-insulator-metal (MIM) structures realized from highly doped semiconductor Si:InAsSb that has a metallic behavior in the infrared range. In the second, part we improved the efficiency of the MIM resonators by using hyperbolic metamaterials that also miniaturize the resonators. In the last part, we propose an ultra-thin universal design that overcomes the material barrier so that the total absorption can be achieved for different spectral ranges without changing the material.

Les travaux visant au développement de capteurs passifs interrogeables sans fil pour sonder des températures supérieures à 600 °C s’inscrivent dans le projet européens SAWHOT. Des capteurs à ondes élastiques de surface sont modélisés, réalisés et caractérisés par une liaison radiofréquence. Le paramètre physique mesuré par ce capteur est la température, avec une mesure au-delà de 900°Cpour les applications de maintenance préventive des turbines à combustion ou pour le contrôle de procédés dans les fours de synthèse de nano-tubes de carbone. Les substrats piezoélectriques standards tels que le quartz ou le niobate de lithium ne sont pas envisageables : l’ensemble de ces travaux s’articule autour de la langasite, substrat piezoélectrique opérant jusqu’à 1470°C et ne présentant aucune température de transition (température de Curie) jusqu’à sa température de fusion située à 1470°C. Compte tenu de la vitesse des ondes élastiques de surface des coupes considérés et également des limitations imposées par les moyens de réalisations technologiques, ces résonateurs sont mesurés sans fil à une fréquence proche de la bande ISM centré en 434 MHz. Les dispositifs ainsi réalisés ont été encapsulés via une procédure innovante de mise en boîtier qui permet alors la mesure de capteurs à ondes élastiques de surface dans des environnements où la température dépasse 700°C. De nombreuses études expérimentales ont alors été menés dans le but d’évaluer les performances des capteurs à ondes élastiques de surface en terme de bilan de liaison radiofréquence, reproductible de la mesure, vieillissement au cours des cycles en températures / Development of wireless passive sensor for temperature measurement above 600°C has been performed in the frame of the European SAWHOT project. In this context, surface acoustic wave sensors have been designed, fabricated and characterized by radiofrequency measurement. Physical parameter measured by these sensors is the temperature, reaching values up to 900°C for monitoring in combustion engines andIn ovens used for carbon nano-tubes growth. In order to measure temperature in harsh environments, classical piezoelectric substrates are not usuable: langasite substrate has been considered as a favorable option since it exhibits no transition temperature and is able to operate until its exhibits no transition temperature and is able to operate until its melting temperature, at 1470 °C. regarding the parameters of the surface acoustic waves and the limitation of the fabrication process and devices, the resonators are measured wirelessly in the ISM band centered at 434 MHz (3μm of interdigital transducer period and a transducers with of 1μm). Two main manufacturing technologies are considered, stepper and nano-imprint technologies. The fabricated devices have been packaged by using an innovative process protecting the devices and allowing fir wireless measurements until 700°C. Multiple experiments have been performed in order to characterize the radiofrequency link between the reader and the sensor, the reproducibility of the measurement, the aging effect on the response of the device after high temperature cycles.

Ce mémoire présente l’étude et la conception d’électroniques d’interrogation de capteurs passifs de grandeurs physiques à base d’ondes élastiques se propageant à la surface de matériaux (SAW) piézoélectriques mono-cristallins. L’objectif consiste à réaliser une électronique d’interrogation capable de sonder la réponse d’un résonateur SAW au travers d’une liaison radiofréquence (RF) sans fils pour en extraire une information de température. [...] Les électroniques présentées dans ce manuscrit fonctionnent sur l’analyse de la puissance rétro-diffusée par le capteur en s’inspirant de l’architecture d’un analyseur de réseau à balayage de fréquence. Deux électroniques d’interrogation sont présentées. La première utilise une synthèse de fréquence directe. La souplesse de générer un signal RF pour exciter le résonateur a donnée naissance à divers algorithmes pour optimiser les performances de la mesure. La vitesse à laquelle le lecteur est capable de sonder le capteur permet l’interrogation de capteurs placés sur un support mobile (axe de moteur). La résolution de mesure obtenue atteint le dixième de degré Celsius. La seconde électronique vise à réaliser une électronique compacte dans le but de réduire le nombre et la consommation des composants en intégrant les chaînes d’émission et de réception. Cette électronique est construite autour d’un radio-modem : ce composant combinant fonctionnalités RF et numériques est détourné de sa fonction principale de communication numérique dansle but d’interroger un résonateur SAW. Les contraintes associées aux constantes de temps,à l’isolation nécessaire et à l’accès à l’étage de réception d’un radio-modem nécessitent une étude préalable approfondie. L’algorithme développé pour ce composant a nécessité l’utilisation de techniques de traitement RADAR pour obtenir la température résultante d’un capteur différentiel bi -résonateurs. Cette électronique a permis de mesurer une température / This report deals with the study and design of interrogation electronics for probing surface acoustic wave (SAW) transducers used as passive wireless sensors of physical quantities.The basic principle is to develop hardware aimed at probing the response of SAW resonators through a radiofrequency wireless link in order to extract a temperature information. Resonators whose operating frequency is centered on the 433.92 MHz ISM band are developed as part oft he SAWHOT project aimed at measuring high (650 oC) temperatures. SAW resonators load energy when stimulated at resonance frequency. Upon stopping emission, this power is returned as a radiofrequency signal. The presented electronic systems operate on the analysis of thepower returned by the sensor, based on a frequency-sweep network analyzer architecture. Twointerrogation units are presented. The former is based on a Direct Digital Synthesis frequency source : the flexibility of this digital approach allows for probing resonating sensors followings everal algorithms meeting various constraints including measurement speed and resolution.Sub-millisecond interrogation resonance frequency identification is compatible with probingthe response of sensors located on mobile targets such as a rotating motor axis. The achieved resolution lies in the 0.1 oC range. The latter approach aims at designing a compact readerwith a reduced number of components, including all the elements of the interrogation chain,and hence a lower power consumption. This approach is based around integrated, single chip,radiomodems : this components combines radiofrequency and digital functionalities and is diverted from its original digital communication purpose for probing SAW sensors. Timing andisolation constraints as well as accessing the analog receiver stage require a dedicated analysis of the functionalities of the various available chips[...]

RF and microwave applications represent one of the fastest-growing segments of the high performance electronics market, where ongoing innovation is critical. Manufacturers compete intensively to meet market needs with reduced cost, size, weight and many other performance criteria demands. Under this scenario, transmission lines based on metamaterial concepts can be considered a very interesting alternative to the conventional transmission lines. They are more compact (compatible with planar manufacturing processes) and present higher degrees of design flexibility. Furthermore, metamaterial transmission lines can also provide many other unique properties not achievable with ordinary transmission lines, such as dispersion or impedance engineering. Nevertheless, the impact in the industry is still not relevant, mostly due to the complexity of the related synthesis and design procedures. These procedures are mainly based on the engineer’s experience, with the help of costly full-wave electromagnetic (EM) simulators and parameter extraction methods. The aim of this thesis is to contribute to simplify and speed up the synthesis and design procedures of artificial transmission lines. In particular, the lines obtained by periodically loading a conventional transmission line with electrically small resonators, such as split ring resonators (SSRs) or its complementary particle (CSRR). The design procedure is automated by using Space Mapping techniques. In contrast to other alternative methods, real synthesis is found from the circuit schematic (that provides a given target response) and without need of human intervention. Some efforts to make the method practical and useful have been carried out. Given a certain target response, it is determined whether it can be physically implemented with a chosen technology, and hence proceeding next to find the synthesis, or not. For this purpose, a two-step Aggressive Space Mapping approach is successfully proposed. In contrast to other methods, the real synthesis is found from certain target circuit values (corresponding to the equivalent circuit model that characterizes the structure to be synthesized). Different efforts have been carried out in order to implement a useful and practical method. Some of them were focused to determine if, given certain circuit parameters (which determine the target response) and certain given technology specifications (permittivity and height of the substrate, technology limits), that response is physically realizable (convergence region). This technique was successfully formulated and it is known as “Two-Step Aggressive Space Mapping Approach”. In this work, the latest improvements made till date, from the synthesis of basic unit cells until different applications and kinds of metamaterial-based circuits, are presented. The results are promising and prove the validity of the method, as well as its potential application to other basic cells and more complex designs. The general knowledge gained from these cases of study can be considered a good base for a coming implementation in commercial software tools, which can help to improve its competitiveness in markets, and also contribute to a more general use of this technology. / Rodríguez Pérez, AM. (2014). Synthesis of Planar Microwave Circuits based on Metamaterial Concepts through Aggressive Space Mapping [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48465 / TESIS

This diploma thesis focuses on suitable innovation of musical instrument marimba. The chosen problem has been verified by three optoins: new bars, new resonators, virtual registers. The work provides an analysis of the whole issue with verification of some samples and their inclusion or exclusion for further use in the research.

The main aim of the thesis is a frequency stabilization of the DFB semiconductor laser diodes. The temperature stability of the laser diode chip, the stability and the noise of the injection current and the backward reflections are the crucial parameters which affects the frequency stability. These influences are described and the resolution is proposed. The theory of the external methods of the frequency stabilization and the comparison of these methods is presented. One method was choosed and this method was realized for 760 and 1540 nm wavelength laser diodes. In this method was used the frequency stabilization based on the linear absorption to the spectral lines of the gases. The diploma work is closed by the measured results of the frequency stability of the used laser diodes and by the comparison of level of stability achieved by the other methods.

We are using organic small molecules as absorbing material to investigate coherent perfect absorption in layered thin-film structures. Therefore we realize strongly asymmetric resonator structures with a high optical quality dielectric distributed Bragg reflector and thermally evaporated wedged organic materials on top. We investigate the optical properties of these structures systematically by selective optical pumping and probing of the structure. By shifting the samples along the wedge, we demonstrate how relations of phase and amplitude of all waves can be tuned to achieve coherent perfect absorption. Thus almost all incident radiation dissipates in the thin organic absorbing layer. Furthermore, we show how these wedged structures on a high-quality reflective dielectric mirror can be used to determine optical dispersion relations of absorbing materials in a broad spectral range. This novel approach does not require any specific a priori knowledge on the absorbing film.