EDF souhaite utiliser la technologie de mesure de température répartie par capteur à fibre optique utilisant l’effet Raman pour réaliser des cartographies de température de certains composants de centrales nucléaires. Les conditions environnementales auxquelles le capteur à fibre optique est soumis sont particulièrement agressives (température de 350 °C et rayonnements gamma ionisants). Les rayonnements ionisants sont responsables de la création de défauts structurels au cœur de la fibre, qui atténuent sa transmission lumineuse, et dont les effets engendrent une erreur de mesure de température pouvant aller jusqu'à l’interruption totale de la mesure. La haute température, quant à elle, dégrade le revêtement protecteur de la fibre optique, ce qui la fragilise mécaniquement. Des irradiations gamma in situ sur des fibres optiques multimodes commerciales à revêtement or protégées par une gaine en acier inoxydable ont été réalisées, à l’aide de deux sources de rayonnements différentes, pour observer l'atténuation radio-induite du capteur à fibre optique en fonction du débit de dose et de la dose cumulée. Les effets du rayonnement à température ambiante, puis à haute température, ont été observés. Ce travail expérimental démontre que la haute température peut être maîtrisée grâce à une fibre à revêtement or, et que la haute température est bénéfique contre l’atténuation de la fibre engendrée par l’irradiation. La mise en œuvre de capteur de température à fibre optique en environnement sévère devient possible, ainsi que l’estimation des incertitudes sur la mesure associée. / EDF is working on Raman distributed temperature sensing using optical fiber sensors in order to map temperature of nuclear power plants big components. The sensor has to sustain harsh environmental conditions (temperatures up to 350 °C and gamma ionizing radiations). Ionizing radiations can create structural defects inside the fiber’s core, which attenuate the light transmission. This phenomenon can lead to temperature measurements errors until no measurement is possible. As for high temperature, it can affect the fiber coating, which mitigate the fiber mechanical resistance.Gamma rays in situ irradiations have been carried out over commercial off-the-shelf multimode gold coated fibers protected with a stainless steel metal tubing, with two different radiation sources, in order to observe radiation-induced attenuation over dose rate or cumulated dose. Effects of gamma rays over gold coated optical fiber sensors have been observed at both room anhigh temperature.This experimental work enlightens that high temperature can be controlled with gold coated fibers, and that the radiation-induced attenuation downsides can efficiently be balanced with high temperature. Implementation of a Raman distributed temperature optical fiber sensor in such harsh environments becomes possible, as well as the associated estimation of measurement uncertainty.

Les pinces optiques permettent de piéger et de manipuler des objets sans contact physique avec de la lumière et ce avec une extrême précision. Son caractère non-invasif et non-destructif en fait un outil idéal pour des applications dans des domaines tels que la biophysique et la médecine. La pince optique conventionnelle utilise un faisceau lumineux fortement focalisé par un objectif de microscope.La fibre optique est un composant très intéressant dans ce domaine puisqu'elle permet de guider la lumière et de piéger optiquement des objets sans l'utilisation de composants optiques encombrants et en limitant des étapes d'alignement. Elle donne ainsi une grande flexibilité et compacité aux pinces optiques.Dans ce contexte, l'objectif de cette thèse a été de développer une pince optique à deux fibres nano-structurées dans le but de piéger des particules de taille micro et nanométrique.Notre pince est constituée de deux fibres optiques gravées chimiquement en forme de pointe et positionnées en vis-à-vis à des distances typiques de 20 nm à 20 µm. Cette configuration à deux faisceaux contra-propagatifs permet d'annuler la pression de radiation de la lumière. Elle a l'avantage d'obtenir un piégeage efficace pour des intensités lumineuses relativement faibles. En outre, les faisceaux ne doivent pas nécessairement être fortement focalisés. Notre dispositif présente une grande souplesse grâce au contrôle in-situ de la position des fibres, l'injection de la lumière dans les fibres et la manipulation de particules individuelles sans aucun substrat.Au cours de ces travaux, nous avons démontré expérimentalement le piégeage stable et reproductible d'une ou plusieurs particules en suspension. Divers types de particules diélectriques ont été piégées, allant de la particule en polystyrène d'un micromètre à des particules luminescentes de YAG:Ce mesurant 60 nm de diamètre. Ces dernières ont été élaborées et optimisées spécifiquement pour le piégeage optique lors de ces travaux.Nous avons également mesuré les forces optiques appliquées aux particules piégées en analysant leur mouvement Brownien résiduel. Nous avons démontré que le potentiel de piégeage était harmonique, nous permettant de définir la constante de raideur optique.Enfin nous avons démontré qu'en modifiant la forme du faisceau optique d'émission, il était possible d'améliorer certaines caractéristiques de la pince. D'une part, les faisceaux quasi-Bessel qui sont très peu divergents nous ont permis de réaliser un piégeage stable et efficace à grande distance.D'autre part, l'utilisation de pointes métallisées permet de confiner le champ et d'améliorer les forces optiques tout en diminuant l'intensité lumineuse. Nous avons mis en évidence le couplage en champ proche entre deux pointes métallisées qui ont été spécialement élaborées pour la pince. Ces derniers résultats ouvrent des perspectives encourageantes pour le développement d'une pince plasmonique fonctionnant en champ proche qui est particulièrement bien adaptée pour le piégeage de nanoparticules. / Optical tweezers allow to trap and manipulate objects without any mechanical contact with light and with an extreme accuracy. This non-invasive and non-destructive technique is of large interest in many scientific domains such as biophysics and medicine. Conventional optical tweezers use a laser beam which is strongly focalised by a microscope objective.The use of optical fibers attracts increasing attention as highly flexible and compact tools for particle trapping. Fiber-based optical tweezers do not require bulky optics and require only little alignments.In this context, the objective of this thesis was to develop a dual fiber nano-tip optical tweezers in order to trap particles with micro and nano-meter sizes. Our tweezers consist of two chemically etched optical fiber tips placed in front of each other with typical gaps from 20~nm to 20~µm. This dual contra-propagative beams configuration allow to cancel light radiation pressure. Efficient trapping can thus be obtained at relative low light intensities. Moreover, strong focusing is not required. Our device present an high flexibility due to in situ optimization and control of the fibre positions and individual particle manipulation without any substrate.During our work, we experimentally demonstrated stable and reproducible trapping of one or several particles in suspension. Various dielectric particles were trapped, from one micrometer polystyrene beads to luminescent YAG:Ce particles with diameters down to 60~nm. During this thesis, the latter were specifically elaborated and optimized for the optical trapping. We also measured optical forces applied to trapped particles by analysing their residual Brownian motion. We showed the trapping potential is of harmonic shape, allowing to define its optical stiffness.vspace{10pt}Finally, by modifying the emitted optical beam shape, we were able to improve specific tweezers characteristics. On one hand, nondiffracting quasi-Bessel beams allow us to get a stable trapping at large fiber-to-fiber distances.On the other hand, the use of metallised fiber tips allows to improve the beam confinement and enhance optical forces while reducing light intensity. We proved the near-field coupling between two metallised tips which were especially elaborated in this work. Those last results open promising perspectives for the development of plasmonic tweezers working in the near-field, which are especially well adapted for nano-particles trapping.

[pt] Este trabalho versa sobre duas diferentes aplicações de sensores a redes de Bragg em fibra óptica. A primeira consiste no desenvolvimento de uma técnica de sensoriamento do pH empregando fibra óptica, que visa a monitoração contínua e permanente deste parâmetro em poços de petróleo depletados e de injeção. Nesta aplicação, as redes de Bragg são acopladas, através de um mecanismo transdutor, a sistemas poliméricos que respondem a alterações do pH apresentando uma variação expressiva de seu volume. O tempo de resposta e o fator de inchamento do sistema polimérico foram caracterizados para valores de pH 3, 4, 5, e 6, em soluções aquosas contendo sais dissolvidos em concentrações típicas das encontradas em águas de formação. As medições foram realizadas a temperaturas e pressões ambientes, assim como na presença de óleo, e após a pressurização do sistema polimérico até 5000 psi. Diferentes mecanismos transdutores foram projetados e construídos, e suas respostas, avaliadas em soluções aquosas com composição similar à das águas de formação. Foram estimadas a sensibilidade da técnica e as principais fontes de incerteza na medição do pH. Procurou-se também avaliar a funcionalidade dos mecanismos transdutores visando uma futura instalação em poço. Na segunda aplicação, é proposta uma técnica para a medição in situ da tensão residual induzida em filmes finos de alta dureza durante sua deposição em câmaras de sputtering assitido por rádio-frequência e campo magnético. A técnica é constituída por uma viga em aço engastada, tendo uma de suas faces instrumentada com um conjunto de redes de Bragg a fibra óptica, enquanto a face oposta é exposta ao fluxo de íons do material a ser depositado. O sistema sensor é instalado em uma câmara que opera sob alto vácuo, enquanto os aparelhos de leitura permanecem no exterior. A resposta do protótipo em função de variações do campo magnético e da temperatura no interior da câmara foi levantada. Em seguinda, foram realizadas medições da deformação da viga durante a deposição de filmes de sílica, de óxido de titânio-índio, e de carbeto de silício. A tensão residual dos filmes foi calculada e comparada com resultados de medições de curvatura do substrato realizadas empregando um perfilômetro. Tensões residuais de 6 MPa até 0,2 Gpa foram obtidas durante as diferentes deposições. / [en] This work treats of two different applications of optical fiber Bragg grating sensors. The first application consists of a pH sensing technique that employs optical fiber to permanent and continuously monitor the pH in depleted and injection oil wells. In this application, the Bragg gratings are coupled by a transduction mechanism to a polymeric system which responds to pH variations with a large volume change. The response time as well as the swelling factor of the polymeric system at pH 3, 4, 5, and 6 have been characterized in aqueous solutions with dissolved salts in concentrations typical of those found in formation waters. Experiments have been carried out at room temperature and pressures, in the presence of oil, and after pressurization up to 5000 psi. Several mechanisms of transduction have been designed, constructed, and tested in solutions similar to the formation waters. The sensitivity of the technique and the main sources of uncertainties related to the pH measurement have been investigated. Also, the functionality of the mechanisms has been evaluated aiming at a future installation in the petroleum wells. The second application investigated is a technique for in situ measurement of the residual stress induced in hard thin films during deposition by RF magnetron sputtering. The sensing technique consists of a cantilever steel beam. One of the surfaces of the beam is instrumented using optical fiber Bragg gratings; the opposite face is exposed to the ion flux that originates the thin film. The sensing system is installed in a vacuum chamber while the interrogating apparatus remains outside. The prototype has been characterized with respect to variations of the magnetic field and the temperature inside the chamber. Measurements of the beam strain have been carried out during deposition of silica, indium- titanium oxide, and silicon carbide thin films. The residual stresses have been calculated and the results compared with data obtained using perfilometry. Residual stress values varying from 6 MPa up to 200 MPa have been obtained during the different deposition processes.

[pt] De acordo com os cálculos do Sindicato Nacional da Indústria de Cerveja (Sindicerv), os estados e o governo federal perdiam anualmente cerca de R$ 720 milhões em arrecadação, devido à sonegação praticada por alguns fabricantes de cerveja. Um elemento facilitador para esse tipo de sonegação é o método atualmente utilizado pela Receita Federal para o controle da quantidade de volume produzido, que envolve apenas o controle de notas fiscais de vendas, o que tem sido uma grande fonte de erros e prejuízo, tanto para as empresas, quanto para o governo. Em 2001, com o objetivo de criar mecanismos que auxiliem no controle de arrecadação de impostos, o governo federal publicou a Medida Provisória no 2.158-35, obrigando os fabricantes a instalar um Sistema de Medição de Vazão (SMV) em todas as linhas de engarrafamento, na entrada de cada enchedora. O SMV seria usado inicialmente apenas no monitoramento. Além de medir a quantidade de bebida produzida, o SMV é, por meio de um sistema de condutivímetro elétrico, responsável por detectar o tipo de líquido que está sendo envasado. Nesta dissertação, são avaliadas possíveis técnicas de diferenciação de bebidas alcoólicas e não-alcoólicas, visando atribuir maior confiança à Receita Federal e aos consumidores. Além da condutividade, foram avaliadas a densimetria e a potenciometria. Devido a problemas encontrados nestas três (3) técnicas, resolveu-se testar a eficiência de um sensor à fibra óptica de índice de refração para a diferenciação de bebidas. A principal vantagem deste sensor é tornar a sonegação mais difícil, pois, ao contrário do condutivímetro, não sofre influência eletromagnética externa. As incertezas de medição dos valores obtidos para condutividade e índice de refração foram calculadas. Os resultados da presente dissertação são suficientemente significativos para substanciar a recomendação de uma revisão da Medida Provisória no 2.158- 35. Parte desta dissertação foi financiada, através do Convênio referência FINEP n° 22.01.0692.00, pelo Programa Tecnologia Industrial Básica e Serviços Tecnológicos para a Inovação e Competitividade MCT/FINEP/FNDCT/Fundo Verde Amarelo, um programa cooperativo universidade- empresa. / [en] According to the Brazilian Sindicato Nacional da Indústria de Cerveja (Sindicerv), about R$ 720 million a year used to be lost due to federal and state tax evasion by some beer manufacturers. Tax evasion used to be eased by the method used by the Brazilian federal revenue service (Receita Federal) to monitor the amount of beer manufactured, which was solely based on sales receipts, resulting in large losses for the government and companies. In 2001, in order to create mechanisms to help in tax collection, the Federal government issued the Medida Provisória no 2.158-35, making it mandatory for the manufacturers to install a Flow Measurement System in all bottling lines, at the beginning of the beverage filler. The system was to be initially used as a monitoring device. In addition to measuring the amount of beverage manufactured, the Flow Measurement System is also responsible for detecting the type of beverage being bottled or canned by means of an electrical conductivity sensor. This and other possible methods for distinguishing between alcoholic and non alcoholic beverages in the Flow Measurement System are evaluated in this dissertation, in order to increase reliability for the Receita Federal and the consumers. In addition to the conductivity, density and pH measurements were also evaluated. Due to problems found in these three (3) techniques, an index of refraction optical fiber sensor was also tested for distinguishing between beverages. The main advantage of this sensor is that it makes tax evasion more difficult because, as opposed to the conductivity sensor, it is not affected by external electromagnetic interference. The uncertainty in measurement of the conductivity and index of refraction results were calculated. This dissertation` results are sufficiently significant to substantiate the recommendation that the Medida Provisória no 2.158-35 be revised. Part of this dissertation was financed by the Convênio referência FINEP n° 22.01.0692.00 of the Programa Tecnologia Industrial Básica e Serviços Tecnológicos para a Inovação e Competitividade MCT/FINEP/FNDCT/Fundo Verde Amarelo, a university-company cooperative program.

[pt] Os efeitos que causam limitações nas comunicações ópticas referentes a polarização se resumem essencialmente na Dispersão dos Modos de Polarização (PMD), nas Perdas Dependentes da Polarização (PDL), e no Ganho Dependente da Polarização (PDG). Estes efeitos podem aparecer na transmissão de forma isolada ou combinada, gerando distorções no sinal. Primeiramente estes efeitos foram estudados individualmente, cada efeito sendo analisado e quantificado sob diversos aspectos. Através de uma analise teórica e experimental foi proposto uma nova técnica de medida de penalidade de potência envolvendo os efeitos estudados. Depois de um estudo detalhado sobre os efeitos isolados, analisou-se os efeitos combinados de PMD e PDL. Diversos emuladores de PMD, elementos com PDL variável e emuladores de PMD e PDL fizeram parte de um longo estudo sobre estes efeitos combinados. Procurou-se ressaltar a importância e os cuidados necessários que se deve tomar para a construção de um emulador de PMD. Na última etapa, foram estudados os efeitos de PMD e PDG oriundos de um sistema utilizando amplificação Raman. Desta forma foi possível evidenciar, caracterizar e relacionar os efeitos da polarização nas fibras ópticas. / [en] The polarization effects that cause limitations in optical communications are essentially the Polarization Mode Dispersion (PMD), the Polarization Dependent Loss (PDL), and the Polarization Dependent Gain (PDG). These effects can appear either isolated or in combinations, generating signal distortion. These effects were first investigated individually under different experimental situations and then combined effects were studied. A new technique for measuring the power penalties corresponding to these effects was proposed. The combined effects of PMD and PDL in PMD emulators were evaluated and quantified. Thumb rules for the manufacture of PDL-free emulators were proposed. The effects of PMD and PDG originated from Raman amplification were also studied and compared with theoretical predictions.

L'objectif de ce travail de recherche est l'étude, la réalisation et la caractérisation d'un amplificateur de puissance à base de verres spéciaux devant être inséré dans un dispositif laser impulsionnel à cohérence élevée opérant a la longueur d'onde de 1550 nm en configuration MOPA (Master Oscillator Power Amplifier). Il aura pour fonction d'amplifier le signal provenant d'un laser source afin de pouvoir le propager sur des distances élevées sans pour autant dégrader ses caractéristiques spectrales ou sa cohérence. Le dispositif ainsi obtenu sera utilisé comme source laser pour des systèmes LIDAR compact pouvant soit être embarqués à bord d'avions ou de voitures; soit être utilisés dans des stations météorologiques ou des aéroports. Un tel projet représente une innovation majeure dans le domaine des capteurs laser fonctionnant en espace libre. Il s'agit en effet de réaliser des dispositifs compacts qui n'existent pour l'instant pas aussi bien de façon commerciale que des les laboratoires de recherche. / The objective of the present research is the study, fabrication and characterization of a power amplifier based on special glasses to be implemented as an embedded module inside a pulsed laser device with high coherence working at 1550 nm wavelength. The optical amplifier represents the second module of a laser in configuration MOPA (Master Oscillator Power Amplifier). The device must amplify the signal proceeding from a seed laser and allow the propagation of the signal at high distances while maintaining the spectral characteristics of the high coherent source. The device obtained with this approach will be employed as a source for a monitoring LIDAR system, which will be installed in train monitoring portals. The results can be extended to other applications as well, such as aeroplanes, meteorological stations or airports. The current research work is intended to contribute to the fabrication of compact devices that seems not be still available even in laboratories. / Lo scopo della presente ricerca `e lo studio, la realizzazione e la caratter-izzazione di un amplificatore di potenza a base di vetri speciali da utiliz-zare come modulo da implementare all’interno di un dispositivo laser adimpulsi ad elevata coerenza operante alla lunghezza d’onda di 1550 nm.L’amplificatore ottico rappresenta il secondo modulo di un laser in configu-razione MOPA (Master Oscillator Power Amplifier): esso ha la funzione diamplificare il segnale proveniente da un laser “seed” e permette di propa-gare il suo segnale ad elevate distanze, mantenendo tuttavia le caratteris-tiche spettrali di elevata coerenza della sorgente. Il dispositivo cos`ı ottenutosar`a utilizzato come sorgente per un sistema LIDAR di rilevazione a bordodi aerei, autoveicoli e stazioni meteorologiche o aeroporti. Questi sistemisembrano non essere ancora disponibili neanche a livello dei laboratori diricerca.

La Thèse a été réalisée en cotutelle entre l’Université Jean Monnet de Saint Etienne (France) et l’université de Palerme (Italie) et en collaboration avec l’Agence nationale pour la gestion des déchets radioactifs (ANDRA). Le travail de recherche concerne l'étude des capteurs répartis à fibres optiques (utilisant la lumière rétrodiffusée Raman et Brillouin) destinés à l’observation et à la surveillance des ouvrages dédiés au stockage géologique de déchets radioactifs de haute activité et moyenne activité à vie longue (projet CIGEO : centre industriel de stockage géologique). Dans ce contexte, les fibres optiques sont envisagées en tant qu’élément sensible de capteurs pour la mesure de paramètres environnementaux tels que la température ou la déformation. Les conditions environnementales extrêmes d’exploitation entrainent la dégradation des propriétés de la fibre optique et des performances du capteur. La réponse des capteurs Brillouin et Raman est influencée par la présence de rayonnement y et d’hydrogène dans l’atmosphère Cigéo. Dans les deux cas, une diminution de la transmission linéique de la fibre optique est observée. Ce phénomène est dû à l’atténuation induite par radiation (RIA) ou par hydrogène (HIA) réduisant ainsi la portée de la mesure. En outre le rayonnement y et l’hydrogène provoquent des erreurs sur la mesure de température ou de déformation pour les deux types de capteurs. L’étude a permis d’établir les lignes directrices pour la sélection et le développement des capteurs repartis à fibre optique appropriés pour travailler dans l’environnement Cigéo / This PhD thesis is conducted in the joint supervision of both the University Jean Monnet of Saint Etienne (France) and the University of Palermo (Italy) in collaboration with the French national agency for the management of radioactive wastes (ANDRA). The aim of the Thesis is to evaluate the performances of distributed optical fiber sensors (based on Raman and Brillouin scattering technologies) that will be employed for monitoring industrial site for deep geological disposal for high and long-lived intermediate level activity radioactive waste (HL-W and LL/IL-W, respectively), called Cigéo. In this context, the distributed optical fiber sensors will provide a time and spatial cartography of the strain and temperature inside the disposal cell. The severe environment of Cigéo requires the sensor evaluation taking into account the resulting degradation of the sensing optical fiber. The sensor response is affected by y-rays and hydrogen presences inside the storage cells. In both cases a decrease of the optical fiber transmission, due to the radiation or hydrogen induced attenuation (RIA or HIA) is observed and limits the sensing distance range of the sensor. Moreover, the two different environment constraints lead to errors in the temperature or strain evaluation for both sensor technologies. This Thesis work establishes the guidelines to select and design distributed optical fiber sensors suitable to operate in radiation environment such as Cigéo one

Les matériaux composites ont connu ces dernières années une forte croissance, croissance aujourd'hui renforcée par les nouvelles normes européenne visant à diminuer les émissions CO2 d'ici 2020. La réalisation de pièces complexes peut poser de nombreuses problématiques de fabrication comme la formation de zones sèches, ou la création de distorsions géométriques. Les origines de ces problématiques sont souvent liées à un manque de connaissance et de maîtrise des phases d'imprégnation des renforts et de cuisson du matériau. L'amélioration de la robustesse des procédés nécessite d'avoir une connaissance fine des phénomènes physiques qui ont lieu lors de l'élaboration. Dans cette perspective, les procédés d'élaboration de matériaux composites ont été étudiés à travers la mise en place d'un démonstrateur de laboratoire dans le cadre du projet LCM Smart. Ce pilote d'injection a permis de valider des solutions d'instrumentation, à partir de capteurs innovants (OFS) développés en partenariat avec le laboratoire d'optique Hubert Curien.L'application de cette instrumentation dans le cadre du suivi du procédé RTM a démontré les capacités des OFS pour le suivi des caractéristiques physiques de la pièce (le front d'écoulement, la température, les déformations résiduelles et le degré de cuisson). La comparaison des caractéristiques mesurées avec des simulations numériques effectuées en collaboration avec ESI, a montré une bonne corrélation.Enfin, l'instrumentation a permis de mettre en évidence l’intérêt d’un outillage composite en HexTool pour la réduction des contraintes résiduelles liées à l'interaction outil/pièce. / A significant growth in production and consumption of composite materials can be seen recently; growth reinforced by the new European standards, aimed at reducing CO2 emissions by the year 2020.The producing of complex parts can cause many difficulties for manufacturing because of their geometries and / or their constituents (using of various materials). For example, dry zones or geometric distortion formation. The origins of these difficulties are often related to a lack of knowledge and control of the reinforcement's impregnation phases and material curing.Improving the robustness of the processes demands a detailed knowledge of physical phenomena that occur during the producing. For this, we studied the composite materials production through the implementation of a laboratory demonstrator in the project LCM Smart. This pilot injection was used to validate instrumentation solutions, from innovative sensors (OFS) developed in partnership with the optical laboratory Hubert Curien. The application of this instrumentation in the context of RTM process monitoring in the development of simple parts has demonstrated the capabilities of OFS to control physical characteristics of the part (the flow front, temperature, residual strain and curing degree). The comparison of the measured characteristics with numerical simulations carried out in collaboration with ESI showed a good correlation.Finally, instrumentation has demonstrated the capacity of composite tool made by HexTool to minimize the residual stresses due to the tool/part interaction.

Formatos de modulação com capacidade de ajuste às condições variáveis de propagação são de interesse para uso em redes ópticas reconfiguráveis. Alterações nos níveis de potência e no mapa de dispersão afetam o desempenho de sistemas de transmissão, limitando o alcance e a capacidade de reconfiguração da rede. Fornecer capacidade de ajuste dinâmico ao sinal transmitido, sem usar sistemas complexos de modulação ou de compensação variável de dispersão, é uma solução eficaz para se obter rendimento ótimo nas diversas condições de propagação na rede. Esta característica também é útil na instalação de redes convencionais, poupando tempo e reduzindo custos. Neste trabalho é proposto o formato de modulação NRZ com gorjeio sincronizado com o sinal como alternativa para sobrepujar as limitações impostas pelas redes reconfiguráveis. O sistema proposto tem o atrativo de permitir, além da capacidade de adaptação, a possibilidade de integração dos componentes ópticos do modulador num mesmo substrato. O desempenho do formato de modulação proposto foi analisado em diversas condições de propagação para sistemas a 10 Gbit/s, tanto em sistemas ponto-a-ponto como de longas distâncias. Esta análise foi feita por meio de modelagem matemática, simulações numéricas e experimentos em laboratório. Foi demonstrada a capacidade de ajuste a diversos mapas de dispersão e seus limites, bem como a compensação de efeitos da automodulação de fase causados por alterações no nível da potência do sinal. / Modulation formats with adjustment capability to the variable propagation conditions are of interest in reconfigurable optical networks. Changes in optical power levels and dispersion compensation map affect the transmission system performance, limiting the range and the network reconfiguration capability. To provide dynamical adjustment capability to the transmitted signal, using neither complex modulation systems nor variable dispersion compensation, is an effective solution to obtain optimal performance within the diverse network propagation conditions. This characteristic is also useful during conventional networks installation, saving time and reducing costs. In this work it is proposed the NRZ modulation format with signal synchronized chirp as an alternative to overcome the limitations imposed by the reconfigurable networks. The proposed system has the benefit of allowing, more than adaptation capability, the possibility of integration of the optical modulator\'s components in the same substrate. The proposed modulation format was analyzed under diverse propagation conditions for 10 Gbit/s, in point-to-point as well as long-haul systems. This analyses war performed by mathematical modeling, numerical simulations and laboratorial experiments. It was demonstrated the adjustment capability for diverse dispersion compensation maps and its limits as well as the compensation of the self-phase modulation effects due to changes in optical power levels.

Este trabalho teve por objetivo desenvolver e caracterizar um sensor de força utilizando uma fibra óptica modificada pelo processo conhecido como Fiber tapering. A fibra quando modificada deixa exposto o campo evanescente, o que a torna sensível a influências externas, e a luz guiada na fibra pode vir a sofrer reflexão interna total frustrada ao entrar em contato com materiais. Ao envolver a região modificada por um material elastomérico, a área de contato e consequentemente a atenuação torna-se uma função da intensidade da força aplicada, possibilitando então relacionar a força a atenuação da luz. Baseando-se nesse efeito, foi criado um sensor de dimensões reduzidas, de rápida resposta, linear, altamente sensível e de boa repetibilidade. Foi criado também um circuito eletrônico utilizando amplificadores operacionais para a aquisição e processamento do sinal proveniente da fibra e selecionado um sensor comercial comum para a realização de experimentos e comparações. Ambos os sensores foram posicionados sobre uma balança de precisão e submetidos a diversos esforços obtendo-se dados sobre a resposta estática. Em seguida utilizando um shaker eletrodinâmico foram medidos os tempos de resposta a uma entrada degrau, e realizando esforços repetitivos foram analisados os desvios das medidas lidas pelos sensores. / The aim of this research was to develop and characterize a force sensor using a modified optical fiber by a process known as Fiber tapering. The modified fiber leaves the evanescent field exposed and prone to external influences and the guided light may suffer frustration of total internal reflection upon contact with materials. When covering the modified fiber section with an elastomeric material, the contact area and therefore the attenuation becomes a function of the applied pressure, making it possible to relate force to attenuation in light intensity. Based on this effect, a small sensor was created, having a quick response time, with high linearity, high sensitivity and good repeatability. Along with the sensor, an electronic circuit using operational amplifiers was designed for acquisition and processing of the signal obtained from the optical fiber. In addition, in order to perform experiments and comparisons, a standard force sensor was chosen. Both sensors were placed over a precision weighing scale and had different intensities of force applied on them, and after that, data regarding static measurements was gathered. The response time was obtained using an electrodynamic shaker and applying a step input. Furthermore, data was gathered about the deviations on the measurements by performing a repetitive set of compressions.