Strongly localised plasmons in metallic nano-structures offer exciting characteristics for guiding and focusing light on the nano-scale, opening the way for the development of new types of sensors, circuitry and improved resolution of optical microscopy. The work presented in this thesis focuses on two major areas of plasmonics research - nano-focusing structures and nano-sized waveguides. Nano-focusing structures focus light to an area smaller than the wavelength and will find applications in sensing, efficiently coupling light to nano-scale devices, as well as improving the resolution of near field microscopy. In the past the majority of nano-focusing structures have been nano-scale cones or tips, which are capable of focusing light to a spot of nano-scale area whilst enhancing the light field. The alternatives are triangular nano-focusing structures which have received far less attention, and only one type of triangular nano-focusing structure is known – a sharp V-groove in a metal substrate. This structure focuses light to a strip of nano-scale width, which may lead to new applications in microscopy and sensing. The difficulty with implementing the V-groove is that the structure is not robust and is quite difficult to fabricate. This thesis aims to develop new triangular nano-focusing devices which will overcome these difficulties, whilst still producing an intense light source on the nano-scale. The two proposed structures presented in this thesis are a metallic wedge submerged in uniform dielectric and a tapered metal film lying on a dielectric substrate, the latter being the easier to fabricate and the more structurally sound and robust. The investigation is performed using the approximation of continuous electrodynamics, the geometrical optics approximation and the zero-plane method. The second aim of this thesis is to investigate plasmonic waveguides and couplers for the development of nano-optical circuitry, more compact photonic devices and sensors. The research will attempt to fill the gaps in the current knowledge of the V-groove waveguide, which consists of a sharp triangular groove in a metal substrate, and the gap plasmon waveguide, which consists of a rectangular slot in a thin metal film. The majority of this work will be performed using the author’s in house finite-difference time-domain algorithm and FEMLAB as well as the effective medium method and geometric optics approximation. The V-groove may be used as either a nano-focusing or waveguiding device. As a waveguide the V-groove is one of the most promising plasmonic waveguides in the optical regime. However, there exist quite a number of gaps in the current knowledge of V-groove waveguides which this thesis will attempt to fill. In particular, the effect of rounded groove tip on plasmon propagation has been assessed for the V-groove. The investigation of rounded groove tip is important, as due to modern fabrication processes it’s not possibly to produce an infinitely sharp groove, and the existing literature has not considered the impact of this problem. The thesis will also investigate the impacts of the inclusion of dielectric filling in the groove on plasmon propagation parameters. This research will be important for optimising the propagation characteristics of the mode for certain applications, but it may also lead to easier methods of fabricating the V-groove device and prevent oxidation of the metal film. The gap plasmon waveguide is easier to fabricate than the V-groove, and is a new type of sub-wavelength waveguide which displays many advantages over other types of plasmon waveguides, including ease of fabrication, almost 100% transmission around sharp bends, sub-wavelength localisation and long propagation distances of the guided mode, etc. This waveguide may prove invaluable in the development of compact photonic devices. In the past the modes supported by this structure were not thoroughly analysed and the possibility of using this structure to develop sub-wavelength couplers for sensing and nano-optical circuits was not considered in detail. This thesis aims to resolve these issues. In conclusion, the results of this thesis will lead to a better understanding of Vgroove and gap plasmon waveguide devices for the development of nano-optical circuits, compact photonic devices and sensors. This thesis also proposes two new nano-focusing structures which are easier to fabricate than the V-groove structure and will lead to applications in sensing, coupling light efficiently into nano-scale devices and improving the resolution of near-field microscopy.

MENEZES, José Wally Mendonça. Análise de performance de sólitons ópticos espaço-temporais em guia planar com não-linearidade cúbico quintica periodicamente modulada e circuitos lógicos operando nos regimes Kerr instantâneo e relaxado. 2010. 149 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2010. / Submitted by francisco lima (admir@ufc.br) on 2014-06-30T18:38:52Z No. of bitstreams: 1 2010_tese_jwmmenezes.pdf: 7446687 bytes, checksum: 708020e7c4ad24658a46a55f2af5ebc6 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2014-08-06T20:53:00Z (GMT) No. of bitstreams: 1 2010_tese_jwmmenezes.pdf: 7446687 bytes, checksum: 708020e7c4ad24658a46a55f2af5ebc6 (MD5) / Made available in DSpace on 2014-08-06T20:53:00Z (GMT). No. of bitstreams: 1 2010_tese_jwmmenezes.pdf: 7446687 bytes, checksum: 708020e7c4ad24658a46a55f2af5ebc6 (MD5) Previous issue date: 2010 / In this work, the propagation and stability of spatiotemporal optical solitons (or optical bullets) in a planar waveguide with periodically modulated cubic-quintic nonlinearity is presented numerically as a function of the amplitudes of modulation , the frequency of modulation and the propagation distance .With the objective of ensure the stability and preventing the collapse or the spreading of pulses, in this study we explore the cubic-quintic nonlinearity with the optical fields coupled by XPM (Cross-Phase Modulation) and take into account several values for the nonlinear parameter , for amplitudes and frequency of modulation as a function of the propagation distance , we cause the collisions of two pulses (envelope of the optical field) to ensure that the optical pulse are sólitons and, after numerical analysis was possible shown the existence of stable spatiotemporal optical sóliton. We also have presented the numerical analysis of the three-core nonlinear fiber coupler in a symmetrical planar structure and operating with instantaneous and relaxed Kerr model for generation of the all-optical logic gates. To implement this optical circuit, we used a control pulse CP with a phase difference between the inputs “I1” and “I2” of the fiber coupler and were analyzed the transmission characteristics, the Extinction Ratio as a function of the phase difference, the length normalized (LN), the figure-of-merit of the logic gates (FOMELG (dB) and the pulse evolution along the fiber coupler and, thus, ensure were demonstrated the possibilities for generating of the all-optical logic gates. / Neste trabalho, a propagação e estabilidade de sólitons espaço-temporais (ou sólitons balas) em um guia de onda planar com não linearidade cúbico quintica periodicamente modulada é apresentada em função da amplitude de modulação , da freqüência de modulação e da distância de propagação . Com o objetivo de garantir a estabilidade e prevenir o colapso ou o espalhamento dos pulsos, exploramos a não-linearidade cúbico quintica com os campos ópticos acoplados por XPM (Modulação de Fase Cruzada) e utilizando diversos valores para o parâmetro não-linear , para as amplitudes e freqüências de modulação em função da distância de propagação , provocamos a colisão de dois pulsos (campos ópticos) para garantir que estes sejam realmente sólitons e, após estas análises numéricas, foi possível mostrar a existência de sólitons espaço-temporais estáveis. Apresentamos, também, a análise numérica de um acoplador triplo não linear de fibras ópticas em uma estrutura planar simétrica e operando com o modelo Kerr instantâneo e relaxado para geração de portas lógicas ópticas. Para implementar estes circuitos, usamos um pulso de controle CP com uma diferença de fase entre as entradas “I1” e “I2” do acoplador e analisamos as características de transmissão, taxa de extinção em função da diferença de fase, a largura normalizada (LN), a figura de mérito para portas lógicas FOMELG(dB) e a evolução dos pulsos ao longo do acoplador e, assim, foi demonstrado as possibilidades para geração das portas lógicas ópticas.

A l’heure où la distribution de l’énergie électrique reste encore en discussion pour les nouvelles générations d’avions de transports civils ou militaires, une remise en cause du niveau des tensions continues disponibles pourrait porter les bus de tension de 270Vdc à 540Vdc. De fait, les équipementiers devront proposer des produits facilement adaptables à ces deux niveaux de tension. Par ailleurs, la course au rendement nécessite de revoir les systèmes actuels en proposant des versions plus compactes, fonctionnant à des meilleurs niveaux de rendement. L’atteinte de ces objectifs peut passer par une rupture technologique qui devrait s’opérer dans le domaine de la conversion d’énergie avec l’avènement, d’une part, des composants « grand gap », d’autre part, l’exploitation de structures innovantes de convertisseurs de puissance autore configurables. Les systèmes associant plusieurs convertisseurs et plusieurs machines, appelés communément Systèmes Multi-Convertisseurs Multi-Machines (SMCMM), jouent également un rôle prépondérant grâce aux avantages qu’ils présentent tels que, la modularité, la sûreté et l’accroissement de puissance. Néanmoins, si a priori, l’innovation technologique porte sur le convertisseur statique, le rendement d’un système électromécanique alliant convertisseur et machine ne correspond pas en général au produit des rendements de chacun des composants qui le constituent. En effet, le fonctionnement global fait apparaître de nouvelles problématiques. Dans ce contexte, la ligne directrice de ces travaux de recherche porte sur une méthodologie générale et le développement d’outils qui permettent d’étudier ces systèmes dans leur globalité. L’enjeu scientifique de cette étude consiste à adapter au mieux la machine à son convertisseur, optimiser la qualité du couple (amplitude et ondulations), donc à dimensionner et optimiser une machine qui réponde non seulement à la fonction principale visée par l’application, produire un couple mécanique à une vitesse donnée, mais qui satisfasse aussi une, voire plusieurs fonctionnalités requises pour l’utilisation d’onduleurs reconfigurables en tension. Afin de constituer une palette d’outils qui permettra de développer une méthodologie générale d’analyse des SMCMM, un outil de génération et de caractérisation systématique des bobinages et des aimants permanents est développé. Ce premier outil couplé à un modèle de type champ, basé sur la résolution analytique des équations du champ magnétique, est capable de fournir les performances électromagnétiques de la machine en fonction des critères du concepteur. Ensuite, un second outil qui permet d’appliquer la théorie d’une vision de conception par l’adéquation des sources du champ dans une machine, est développé. Nous pouvons alors rechercher la possibilité de maximiser le couple en adaptant, soit les bobinages, soit les aimants permanents. Pour étendre les précédents résultats à un cas général, un problème d’optimisation est formulé. Pour cela, un problème inverse à variables mixtes, relations complexes et non linéaires, est résolu avec un algorithme de type « boîte noire ». Les travaux se focalisent ensuite sur l’intégration de la fonction coupleur magnétique, puis sur la mise en évidence des conditions de fonctionnement optimal d’une machine synchrone à aimants permanents montés en surface et à double étoile (MSAPDE), alimentée par deux convertisseurs en parallèle reconfigurables en tension à commande entrelacée. Cette démarche est une première approche concrète de l’intégration machine convertisseur. Les courants induits dans les parties conductrices de la machine en mouvement sont modélisés afin de vérifier en fonction de la fréquence, leurs effets sur la fonction de coupleur magnétique. Finalement, après des simulations numériques qui permettent d’analyser et de classifier les avantages et les inconvénients de plusieurs solutions de machines, la réalisation de deux démonstrateurs de MSAPDE à coupleur intégré est initiée. / At the moment, distribution of electrical power is still being discussed for the new generations of civil and military aircraft. Level of DC voltage available is challenging and could take voltage from 270Vdc to 540Vdc. Hence, equipment suppliers must propose products easily adaptable to these two voltage levels. Otherwise, the race for better performances requires the revision existing systems by offering more compact versions functioning at better efficiency levels. Achieving these goals may be through a technological breakthrough that should be operated in the field of energy conversion with advent of both components "high band gap", and the use of innovative structures of self-reconfigurable power converters. Systems that combine several converters and several machines, commonly called Multi-Converters Multi-Machines Systems (SMCMM), also play a prominent part thanks to their advantages such as, modularity, safety and increased power. Nevertheless, if in principle, technical innovation concerns with the static converter, the efficiency of an electromechanical system which combines machine and converter does not correspond generally to the efficiency product of each constituent component. Indeed, overall functioning reveals new problems. In this context, the guidelines for this research work focus on a general methodology and the development of tools in order to study these systems as a whole. The scientific challenge of this study consists in adapting a machine to its converter, optimizing the torque quality (amplitude and ripples), so to size and to optimize a machine that meets not only the main function covered by the application, i.e. to produce a mechanical torque at a given speed, but also satisfies one or several functionalities required for using reconfigurable voltage inverters. In order to provide a range of tools that will allow the development of a general methodology for SMCMM analysis, a tool for automatic generating and characterizing windings and permanent magnets has been developed. This first tool coupled with an analytical model of field type, based on solving equations of magnetic field, is able to provide electromagnetic performances of the machine according to the designer's criteria. A second tool which allows us to apply theory of a design vision by the field sources adequacy in a machine has been developed. Consequently, we can look for possibility to maximize torque by adapting either windings or permanent magnets. To extend previous results to a general case, an optimization problem is formulated. For this purpose, an inverse problem with mixed variables, complex and non-linear relations, is solved with a "black box" algorithm. The work focus on magnetic coupler function integration, on the identification of optimal operating conditions of a synchronous machine with surface-mounted permanent magnets (AP) and double star (MSAPDE), supplied by two reconfigurable parallel interleaved inverters. This approach is a first practical step into machineconverter integration. Eddy currents in the moving conductive parts of the machine are modeled in order to check their effects on the magnetic coupler function according to frequency. Finally, after numerical simulations which allow us to analyze and classify pros and cons of several machine solutions, the fulfillment of two MSAPDE demonstrators integrating magnetic coupler is initiated.

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Neste trabalho, a propagaÃÃo e estabilidade de sÃlitons espaÃo-temporais (ou sÃlitons balas) em um guia de onda planar com nÃo linearidade cÃbico quintica periodicamente modulada à apresentada em funÃÃo da amplitude de modulaÃÃo , da freqÃÃncia de modulaÃÃo e da distÃncia de propagaÃÃo . Com o objetivo de garantir a estabilidade e prevenir o colapso ou o espalhamento dos pulsos, exploramos a nÃo-linearidade cÃbico quintica com os campos Ãpticos acoplados por XPM (ModulaÃÃo de Fase Cruzada) e utilizando diversos valores para o parÃmetro nÃo-linear , para as amplitudes e freqÃÃncias de modulaÃÃo em funÃÃo da distÃncia de propagaÃÃo , provocamos a colisÃo de dois pulsos (campos Ãpticos) para garantir que estes sejam realmente sÃlitons e, apÃs estas anÃlises numÃricas, foi possÃvel mostrar a existÃncia de sÃlitons espaÃo-temporais estÃveis. Apresentamos, tambÃm, a anÃlise numÃrica de um acoplador triplo nÃo linear de fibras Ãpticas em uma estrutura planar simÃtrica e operando com o modelo Kerr instantÃneo e relaxado para geraÃÃo de portas lÃgicas Ãpticas. Para implementar estes circuitos, usamos um pulso de controle CP com uma diferenÃa de fase entre as entradas âI1â e âI2â do acoplador e analisamos as caracterÃsticas de transmissÃo, taxa de extinÃÃo em funÃÃo da diferenÃa de fase, a largura normalizada (LN), a figura de mÃrito para portas lÃgicas FOMELG(dB) e a evoluÃÃo dos pulsos ao longo do acoplador e, assim, foi demonstrado as possibilidades para geraÃÃo das portas lÃgicas Ãpticas. / In this work, the propagation and stability of spatiotemporal optical solitons (or optical bullets) in a planar waveguide with periodically modulated cubic-quintic nonlinearity is presented numerically as a function of the amplitudes of modulation , the frequency of modulation and the propagation distance .With the objective of ensure the stability and preventing the collapse or the spreading of pulses, in this study we explore the cubic-quintic nonlinearity with the optical fields coupled by XPM (Cross-Phase Modulation) and take into account several values for the nonlinear parameter , for amplitudes and frequency of modulation as a function of the propagation distance , we cause the collisions of two pulses (envelope of the optical field) to ensure that the optical pulse are sÃlitons and, after numerical analysis was possible shown the existence of stable spatiotemporal optical sÃliton. We also have presented the numerical analysis of the three-core nonlinear fiber coupler in a symmetrical planar structure and operating with instantaneous and relaxed Kerr model for generation of the all-optical logic gates. To implement this optical circuit, we used a control pulse CP with a phase difference between the inputs âI1â and âI2â of the fiber coupler and were analyzed the transmission characteristics, the Extinction Ratio as a function of the phase difference, the length normalized (LN), the figure-of-merit of the logic gates (FOMELG (dB) and the pulse evolution along the fiber coupler and, thus, ensure were demonstrated the possibilities for generating of the all-optical logic gates.

Made available in DSpace on 2016-03-15T19:38:54Z (GMT). No. of bitstreams: 1 RODRIGO MENDES GEROSA.pdf: 6396087 bytes, checksum: b904e08a314dcda72a403496699b5206 (MD5) Previous issue date: 2015-08-26 / Fundo Mackenzie de Pesquisa / This thesis describes the development of new photonic devices produced by micromanipulation of the optical fibers properties, i.e., the change, in the micrometer scale, of the fiber s optical and/or geometrical properties. In this context, three lines of research have been followed, using different optical fiber processing techniques and considering different types of devices. In the first line, the coupling of two cores in a photonic crystal fiber with three initially uncoupled cores was demonstrated. The couplers had an insertion loss estimated at ~1 dB and exhibited spectral modulations with a depth up to 18 dB. They also showed high sensitivity to polarization, which can be exploited in fiber polarization beamsplitters. For this work, we used a technique that modifies the fiber structure by applying local differential pressure and heating. In the second line, a Rhodamine dye laser was develop with a fully fiber integrated optofluidic cavity. It was possible to maintain a high flow of the dye solution, up to 400 μL / min, which allowed the use of a pump laser with a high repetition rate (1 kHz), and, at the same time, the degradation of the gain medium was not observed. An optical conversion rate of up to 9% and a pump energy threshold lower than 1 mJ were obtained. A splicing technique was used, in which an angled cleaved capillary fiber was fused to a conventional fiber, thereby leaving a side inlet open for the fluid flow. The third line aimed at the incorporation of carbon nanomaterials to optical fibers. In this case, two approaches were employed: in one of them, polymeric films, with a thickness of 20 μm, containing carbon nanotubes were produced on the face of optical fiber patchcords; such patchcords have been inserted into erbium-doped fiber laser cavities to act as saturable absorbers in order to obtain mode-locking operation. Pulses with durations down to 364 fs were obtained with 10.2 nm bandwidths. The films were formed when a micro-droplet of a carbon nanotube suspension on an optical adhesive was placed on the surface of optical fiber connectors, with the use of a micropipette. Within the same line, photonic crystal fibers (PCFs) with homogeneous graphene oxide films covering the inner walls of their capillaries were obtained. The homogeneity was confirmed by Raman spectroscopy and by the loss per fiber length, as measured by the cut back method. A PCF was also spliced to conventional connectorized fiber patchcords and incorporated into a laser cavity to generate pulses. The film production was consisted of inserting a graphene oxide suspension into the PCF capillaries, after which the solvent was dried. / Essa tese descreve o desenvolvimento de novos dispositivos fotônicos produzidos a partir da micromanipulação das propriedades de fibras ópticas, isto é, da alteração em escala micrométrica, das propriedades ópticas e/ou geométricas destas. Nesse contexto, três linhas de trabalho foram seguidas, utilizando diferentes técnicas de processamento de fibras ópticas e levando à demonstração de diferentes tipos de dispositivos. Na primeira linha foi demostrado o acoplamento de dois núcleos em uma fibra de cristal fotônico com três núcleos inicialmente desacoplados. Os acopladores apresentaram uma perda de inserção estimada de ~1 dB e exibiram modulações espectrais com uma profundidade de até 18 dB. Apresentaram também uma sensibilidade elevada à polarização, que pode ser explorada em divisores de polarização (polarization beamsplitters) a fibra. Para isso foi utilizada uma técnica de alteração da estrutura da fibra através da aplicação de pressão diferencial e aquecimento local,. Na segunda linha foi desenvolvido um laser do corante Rodamina com uma cavidade optofluídica totalmente integrada em fibra. Nela, era possível manter um alto fluxo da solução de corante, de até 400 μl/min, o que permitiu utilizar um laser de bombeio com alta taxa de repetição (1kHz) sem observar-se degradação do meio de ganho. Uma taxa de conversão óptica de até 9% e uma energia de limiar (threshold) menor que 1 μJ foram obtidas. Utilizou-se aqui uma técnica de emenda através da qual uma fibra capilar clivada em ângulo era emendada com uma fibra convencional, deixando assim uma entrada lateral para fluidos. A terceira linha visou incorporar nanomateriais de carbono a fibras ópticas. Nesse caso duas abordagens foram empregadas: em uma, filmes poliméricos com espessuras de 20 μm e contendo nanotubos de carbono foram produzidos na face de conectores de cordões de fibra ópticas; esse cordões foram inseridos em cavidades laser a fibra dopada com érbio para atuar como absorvedores saturáveis para a obtenção de mode locking. Com isso foram obtidos pulsos de até 364 fs e espectros com larguras de banda de 10,2 nm. Os filmes foram formados a partir de uma microgota de uma suspensão de nanotubos de carbono em adesivos ópticos que foi colocada sobre a face de conectores de fibra óptica com uma micropipeta. Ainda na mesma linha obtiveram-se fibras de cristal fotônico (PCFs) com filmes de óxido de grafeno homogêneos no interior de seus capilares. A homogeneidade foi comprovada através de espectroscopia Raman e pela medida da perda em função do comprimento das fibras, realizada através do método cut back. Uma PCF foi, ainda, emendada a cordões de fibra convencional conectorizados e incorporada a cavidades laser para geração de pulsos. A produção dos filmes foi realizada através da inserção de uma suspensão de óxido de grafeno nos capilares de PCFs de núcleo sólido, após o qual o solvente era secado.

L’apparition de convertisseurs multicellulaires parallèles entrelacés et magnétiquement couplés a conduit ces dernières années à améliorer les performances des convertisseurs (densité de puissance, efficacité, dynamique,...). Il existe plusieurs topologies d’entrelacement qui utilisent des Transformateurs Interphases. L’objectif principal de cette étude est de trouver parmi ces topologies celles qui sont les mieux adaptées à un contexte d’intégration d’électronique de puissance pour minimiser la taille et réduire les pertes. Une première étape de modélisation a permis d’effectuer une étude comparative de quelques topologies. Un procédé de permutation des phases d’alimentation a été présenté afin de réduire les ondulations du courant de phases et les pertes ohmiques. Les résultats obtenus valident qualitativement l’avantage de la solution retenue par rapport à la solution standard. Enfin, la réalisation pratique d’un prototype de convertisseur modulaire utilisant des Transformateurs Inter-phases est abordé. Il s’agit d’un régulateur chargé d’alimenter les microprocesseurs (1,2V/100A) (Voltage Regulator Module (VRM)) à 5 modules. Les résultats expérimentaux montrent l’avantage de l’utilisation des Transformateurs Inter-phases par rapport à la solution classique / During the last years, using coupled parallel interleaved converters enhances converters performances (power density, efficiency, transient response,...). There are several possible interleaved coupled topologies that use Inter-phases Transformers. The main objective of this study is to find among these topologies the best adapted configuration in a context of power electronics integration in order to minimize converter size and to reduce losses. A model is proposed to compare some topologies. An optimal modified sequence of phase order to reduce current ripple and ohmic losses is presented. The obtained results validate the advantage of the coupled solution compared to the standard solution. At last, the implementation of a modular power converter using Inter-phases Transformers is shown. It is a Voltage Regulator Module (1,2V/100A) that consists of five identical modules. Experimental results show the advantage of using Inter-phases Transformers compared to conventional solution

The objective of the research is to design an electro-optic control for the Active Vertical Coupler-based Optical Cross-point Switch (OXS). The electronic control should be implemented on Printed Circuit Board (PCB) and therefore the design will include the PCB design as well. The aim of the electronic control board is to process the headers of the packets prior to entering the OXS to be switched and from the information in the headers, determine the state that the OXS should be configured in. It should then configure the optical cross-point accordingly. The electronic control board should show flexibility in the sense that it can handle different types of traffic and resolve possible contention that may occur. The research seeks to understand the problems associated with Photonic Packet Switching (PPS) networks. Two of the main problems identified in a PPS network are contention resolution and the lack of variable delays for storing optical packets. The OXS was analyzed and found to meet the requirements for future ultra-high speed PPS network technology with its high extinction ratio, wide optical bandwidth, ultra-fast switching speed and low crosstalk levels. Photonic packets were generated with 4-bit, 8-bit or 16-bit headers at a bit rate of 155 Mbit/s followed by a PRBS (Pseudo Random Bit Sequence) payload at 10 Gbit/s. Different scenarios were created with these types of packets and the electro-optic control and OXS were subjected to these scenarios with the aim of testing the flexibility of the electro-optic control to control the OXS. These scenarios include: <ul><li>Fixed length packets arriving synchronously at one input of the OXS. Some packets are destined for output 1, some are destined for output 2 and some are destined for output 3, therefore realizing a 1-to-3 optical switch.</li> <li>Eight variable length packets arriving synchronously at the OXS at one input, all of them destined for one output. The electro-optic control should open the switch cell for the correct amount of time.</li> <li>Three variable length packets arriving synchronously and asynchronously at one input of the OXS. Some packets are destined for output 1 while other packets are destined for output 2. The electro-optic control should open the correct switch cell for the correct amount of time.</li> <li>Two fixed length packets arriving at the OXS synchronously on different input ports at the same time, both destined for the same output port. The electro-optic control should detect the contention and switch the packets in such a way as to resolve the contention.</li> The electro-optic control and OXS managed to switch all these types of data traffic (scenarios) successfully and resolve the contention with an optical delay buffer. The success of the results was measured in two ways. Firstly it was deemed successful if the expected output sequence was measured at the corresponding output ports. Secondly it was successful if the degradation in quality of the packet was not drastic, meaning the output packets should have an BER (Bit Error Rate) of less than 10-9. The quality of the packets was measured in the form of eye diagrams before and after the switching and then compared. The research resulted in the design and implementation of a flexible electro-optic control for the OXS. The problem of contention was resolved for fixed length synchronous packets and a proposal is discussed to store packets for variable lengths of time by using the OXS. This electro-optic control has the potential to control the OXS for traffic with higher complexities and make the OXS compatible with future developments. / Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2008. / Electrical, Electronic and Computer Engineering / MEng / unrestricted

Down converter is a mixer which have a three ports. Two ports are refered as input ports and one port is ouput. One input port is connected to a signal which is transmited by meteorological satellites at frequency 1,7 GHz this frequency falls within the L–band. Meteorogical images are trasmited in L-band. The second input port is connected to a local oscillator in this case voltage control oscillator. The output signal includes sum and differential products, for down conversion is logically used differential product. Down conversion is used to convert data that are transmitted at high frequency to lower frequency which can be futher processed and then displayed data on the end device.

De nouveaux besoins dans le domaine des télécommunications par satellite ont amené les industriels du secteur à se pencher sur l’optimisation des ressources en créant des systèmes reconfigurables, capables d’adapter leur fonctionnement fréquentiel en cours de mission. Cette thèse s’intéresse plus particulièrement aux multiplexeurs et à la manière de les rendre agiles à travers les filtres qui les composent ainsi qu’une adaptation de leur architecture.Dans un premier temps, le présent manuscrit dresse l’état de l’art des dispositifs accordables réalisés par les équipes de recherche du monde entier, avant de proposer des solutions mettant en œuvre une topologie de multiplexage à coupleurs hybrides. Dans un second temps, des études sont présentées portant sur une pluralité de concepts de cavités ou d’éléments de couplage accordables. Certains de ces concepts sont ensuite sélectionnés et assemblés afin de former des fonctions de filtrage et de multiplexage accordables. La dernière partie présente ainsi deux multiplexeurs accordables, l’un permettant une reconfiguration en bande étroite, l’autre en bande large, le premier ayant donné lieu à une réalisation expérimentale. / New needs in the field of satellite telecommunications have led manufacturers in the sector to focus on optimizing resources by creating reconfigurable systems able to adapt their operating frequencyplan during the mission. This thesis focuses on multiplexers and how to make them agile through their architecture and the filters that compose them.This manuscript starts by realizing the state of the art oftunable filtering devices through analysis of contributions made by research teams around the world. Based on this state of art,solutions to the problematic are proposed using a hybrid coupler multiplexing topology. Then studies are presented on various tunable cavities or coupling elements concepts. Some of these concepts have been selected and assembled to form tunable filtering and multiplexing functions. The last part thus presents two tunable multiplexers, allowing narrowband or broadband reconfiguration. An experimental realization has also been conducted on the narrowband version.

För att vara konkurrenskraftiga på marknaden tvingas företag utveckla nya strategier för produktutveckling, som kan anpassas till allt högre kundbehov. Syftet med detta arbete var att effektivisera produktutvecklingen för företag inom tillverkningsindustrin. Målet var att utveckla en effektiv arbetsprocess för produktutveckling samt att tillämpa processen på ett projekt, där ett helautomatiskt snabbfäste till mindre hjullastare skulle standardiseras till företaget OilQuick.Examensarbetet delades in i två delar. Den första delen behandlar skapandet av arbetsprocessen. Denna grundas i befintlig forskning och identifierades genom en litteraturstudie. Den andra delen behandlar tillämpning av arbetsprocessen på standardiseringen av snabbfästet till hjullastare. Data och kunskap till arbetet samlades in genom marknadsundersökningar, studiebesök, möten med kunder och Reverse Engineering. Kundkraven rangordnades med Best-worst metoden och översattes till tekniska produktegenskaper med Kvalitetshuset.Tre koncept genererades i Autodesk Inventor utifrån kraven och produktegenskaperna, samt datan som framkom av Reverse Engineering och marknadsundersökningen. Enligt kundkravet behövde det färdiga snabbfästet passa minst fyra olika hjullastarmodeller i viktklassen fem till åtta ton. Detta medförde att alla tre koncepten modulbaserades, både för att underlätta eventuella modifikationer mellan hjullastarmodellerna och för att minimera antalet detaljer som behövde modifieras. Alla tre konceptens redskapsgrindar hade standardiserade mått som passade de undersökta hjullastarmodeller. Det koncept som bäst uppfyllde kundkraven utvärderades med Fuzzy TOPSIS metoden. Det slutgiltiga konceptet justerades utifrån kundens önskemål innan det färdiga resultatet presenterades.Resultatet visade att arbetsprocessen var effektiv; Reverse Engineering och samarbetet med kunden gav en inblick i problematiken och förståelse för produkten, Best-worst metoden gjorde att rangordningen av kraven gick snabbt utan att minska på pålitligheten och Fuzzy TOPSIS metoden effektiviserade konceptvalet samtidigt som alla inblandades åsikter blev hörda. För att effektivisera produktutvecklingen ytterligare bör fler metoder undersökas alternativt utvecklas.Konceptförslagen som konstruerades påvisade att det är möjligt att standardisera gränssnittet mellan hjullastare och redskap. Genom modulärkonstruktion kunde snabbfästet anpassas till fyra olika hjullastarmodeller. Innan vidareutveckling av snabbfästet bör fler hjullastare mätas upp och studeras. / In order to be competitive in the market, companies are forced to develop new strategies that can be adapted to ever-increasing customer requirements. The purpose of the work was to streamline product development for companies in the manufacturing industry. The objective was to develop an efficient work process for product development and apply the process to a project where a standardized fully automatic quick coupler for smaller wheel loaders would be developed for the company OilQuick.The thesis was divided into two parts. The first part deals with the development of a work process based on existing research. The second part deals with the application of the work process. Data for the application was collected through market research, meetings with customers and Reverse Engineering. Customer requirements were ranked using the Best-worst method and translated into technical specifications using the method QFD (House of Quality).Three concepts were generated based on the resulting requirements from the QFD. According to the customer requirements, the quick coupler had to be compliant with at least four different wheel loader brands in the weight span from five to eight tons. This meant that all three concepts were based on modular design, both to facilitate modifications between the wheel loader brads and to minimize the number of details that needed to be modified. All three of the concept's attachment brackets had standardized dimensions that fitted all examined wheel loader models. To determine which concept that best met the customer requirements the Fuzzy TOPSIS method was used. The final concept was adjusted based on OilQuick's requirements before the finished result was presented.The results showed that the work process was efficient and reliable and that the developed concept proposal indicates that it is possible for the company to standardize the interface between wheel loaders and attachments. With modular design the quick coupler can be adapted to the wheel loader brands that were studied. To ensure that the quick coupler can be applied to a larger variety of wheel loaders, it is necessary to examine and take measurements of more wheel loader brands before further development.