Orientadores: José Barreto Campello Carvalheira, Cristiano Monteiro de Barros Cordeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-16T22:41:20Z (GMT). No. of bitstreams: 1 Lixandrao_RenataRodriguesdosSantos_M.pdf: 9485549 bytes, checksum: e66206316ef01c5412be9d8bb78185ec (MD5) Previous issue date: 2010 / Resumo: O tratamento radioterápico é um procedimento capaz de matar células tumorais, expondo elas a doses pré-calculadas de radiação ionizante. A precisão na entrega da dose é fundamental para se obter um tratamento seguro e eficaz. Com o intuito de minimizar as incertezas referentes ao tratamento, é de extrema importância a implementação de procedimentos de Controle de Qualidade (CQ). O presente trabalho apresenta o desenvolvimento e validação de um sistema de detecção de radiação para CQ de feixes clínicos de fótons de megavoltagem. O dosímetro desenvolvido é composto de uma mistura de antraceno e polímero óptico, inserida num capilar de SiO2. O capilar foi acoplado à uma fibra óptica de poly(methyl methacrylate), PMMA, que conduziu o sinal luminoso até a fotomultiplicadora, localizada exteriormente a sala de irradiação e conectada a um eletrômetro. O sinal medido está relacionado à taxa de dose a qual o dosímetro foi exposto. A remoção do sinal de Cerenkov foi realizada utilizando uma fibra de referência para posterior subtração do sinal. A caracterização e os testes de performance do dosímetro foram realizados utilizando um feixe de fótons de 6 MV de um acelerador linear clínico. O desempenho do dosímetro e alguns parâmetros do feixe foram obtidos, analisados e comparados a uma câmara de ionização tipo Farmer FC65. Resultados obtidos demonstraram que o polímero óptico misturado ao antraceno reduziu os efeitos de espalhamento da luz emitida pelo volume sensível, aumentando a eficiência de detecção do sistema. O volume sensível é cerca de 100 vezes menor que o da câmara FC65. A quantidade de luz emitida pelo cintilador e, consequentemente, as leituras obtidas pelo sistema de detecção, aumentam linearmente com a taxa de dose. Medidas de reprodutibilidade foram validadas utilizando análise de variância (ANOVA). As curvas de Porcentagem de Dose Profunda (PDP) e de perfil de dose estão em concordância com as leituras do sistema de referência. Medidas em tempo real realizadas com o dosímetro são coerentes e confiáveis, tornando-o viável para a utilização em CQ. Devido, principalmente, ao seu tamanho reduzido, apresenta um grande potencial para ser usado em casos onde uma alta resolução espacial é necessária (por exemplo, em radiocirurgia e Radioterapia de Intensidade Modulada) / Abstract: Radiation therapy is a procedure capable of kill tumor cells, exposing them to precalculated doses of ionizing radiation. The precision in dose delivery is essential for obtain a safe and effective treatment. To minimize the uncertainties related to treatment, it is extremely important to implement Quality Control (QC) procedures. This work presents development and validation of a radiation detection system for clinical megavoltage photons beams QC. The designed dosimeter is composed of an anthracene and optical polymer mixture inserted on a SiO2 capillary. The capillary was coupled to a poly (methyl methacrylate), PMMA, optic fiber that led the light signal to the photomultiplier located outside the irradiation room and connected to an electrometer. The signal measured is related to the dosimeter exposed dose rate. Removal of the Cerenkov signal was performed using a reference fiber for signal subtraction. The dosimeter characterization and performance tests were performed using a 6 MV clinical linear accelerator photon beam. The dosimeter performance and some beam parameters were obtained, analyzed and compared to a Farmer type ionization chamber FC65. Results showed that the optical polymer mixed with anthracene reduced volume sensitive scintillation light scattering, increasing the system detection efficiency. The sensitive volume is about 100 times smaller than the FC65 camera. The scintillator light emission and, hence, the system detection readings, increase linearly with dose rate. Reproducibility measures were evaluated using analysis variance (ANOVA). The curves of percentage depth dose (PDD) and dose profile are consistent with the system reference readings. Real-time measurements performed with the dosimeter are consistent and reliable, making it feasible for use in QC. Due, mainly, to its small size, has great potential to be used in cases where a high spatial resolution is required (for example, radiosurgery and Intensity Modulated Radiotherapy) / Mestrado / Ciencias Basicas / Mestre em Clinica Medica

D.Ing. / Optical fibre-based devices (e.g. fibre gratings) play an important role in the optical com- munications and sensing industry. One type of fibre grating, the long-period grating (LPG), is becoming more and more popular as a simple and versatile component for a multitude of applications in optical engineering. The sensitivity of LPGs to various external perturbations and their ability to manipulate selectively light propagating in optical fibres make them well- suited to creating fibre-based devices. LPGs can be used in various applications, for example as gain equalisers for erbium-doped fibre amplifiers, as channel routers in optical add-drop multiplexers and as sensors. LPGs are typically fabricated by exposing photosensitive optical fibre to ultraviolet light. However, a variety of other techniques can be used to fabricate LPGs, including exposure to carbon dioxide (CO2) laser light. Over the years, it has become evident that CO2 laser- induced LPGs exhibit unique properties and features that can be harnessed to develop devices for important applications. It is necessary to understand the physical properties and optical characteristics of CO2 laser-induced LPGs to harness, manipulate and enhance their features. Research has been conducted on the development of an automated fabrication system that produces axially symmetric LPGs in single-mode fibre with a CO2 laser. A detailed study was undertaken on the design of uniform and non-uniform LPGs for wavelength-division multiplexing networks, as well as the characterisation of the CO2 laser beam propagating in the LPG fabrication system. These LPGs have been designed, using either analysis or syn- thesis techniques. The polarisation-dependent loss of the LPGs has also been investigated. Wavelength-selective couplers (WSCs) have been constructed using CO2 laser-induced LPGs and it was shown that these couplers were e®ective but not efficient in routing power to the output port of the tapping fibre. The physical properties, optical transmission characteris- tics, applications and other related issues of CO2 laser-induced LPGs have been investigated and satisfactory experimental results have been obtained. Areas for potential future research concerning CO2 laser-induced LPGs have been identified and discussed.

Les travaux réalisés dans ce manuscrit portent sur l'étude de la génération de supercontinuum dans des fibres transparentes dans le moyen infrarouge. Afin de générer un supercontinuum entre 3 et 5 µm, nous chercherons à comparer différentes familles de verres tels que les verres de fluorures, les verres d'oxydes de tellures et les verres de chalcogénures. Ces fibres sont pompées à l'aide de laser à fibre émettant autour de 2 µm en régime impulsionnel nanoseconde ou picoseconde. Cette longueur d'onde permet de s'approcher du zéro de dispersion chromatique de certaines fibres. Nous générons un supercontinuum jusqu'à 3800 nm dans des verres fluorés. Une connectique, dont la transmission est d'environ 75 %, est réalisée entre une fibre ZBLAN et une fibre SiO2. Une mesure des raies d'absorption du méthane est réalisée autour de 3300 nm à l'aide du supercontinuum généré dans les verres fluorés. Un supercontinuum est généré jusqu'à 2900 nm dans une fibre en oxyde de tellure. L'étendue du spectre aux grandes longueurs d'onde est limitée par l'atténuation de la fibre. Enfin, plusieurs compositions de verres de chalcogénures sont testées (As38Se62, As40S60, Ge10As22Se68). Ces fibres seront tout d'abord pompées dans leur régime de dispersion normale et nous observerons la formation de 4 sauts Raman successifs. Le gain Raman dans les verres AsSe est estimé à (1,6+/- 0,5) x 10E-11 m/W. Un compromis entre le contrôle de la dispersion chromatique et le couplage dans la fibre nous conduit à réaliser des fibres effilées dont le diamètre varie sur la longueur de la fibre. Nous obtiendrons alors un supercontinuum dans une fibre effilée en verre d'AsSe jusqu'à 2600 nm / The work reported in this thesis deals with the study of the supercontinuum generation in fibers transparent in the mid-infrared. To generate a supercontinuum between 3 and 5 µm we compare different glass families such as fluoride glasses, tellurite glasses and chalcogenide glasses. These fibers are pumped with fiber lasers emitting at 2 µm with nanosecond or picosecond pulse duration. This wavelength allows us to reach the zero dispersion wavelength of the chalcogenide tapered fibers. We report supercontinuum generation up to 3800 nm in a fluoride glass fiber. A connection with 75 % of transmission is made between a ZBLAN and a SiO2 fiber. We also measured absorption lines of the methane at 3300 nm. We report supercontinuum generation up to 2900 nm in an oxyde tellurite fiber. The supercontinuum edge at long wavelength is limited by the OH absorption of the fiber. Finally, several chalcogenide glass compositions and geometries are tested (As38Se62, As40S60, Ge10As22Se68). These fibers are pumped in their normal dispersion regime and we observe the four cascaded Raman shifts. The Raman gain coefficient in the AsSe glasses is estimated to be (1,6+/- 0,5) x 10E-11 m/W.A trade-off between the chromatic dispersion control and the coupling in the fiber leads us to use tapered fibers whose diameter varies along the length of the fiber. We report supercontinuum generation in an AsSe tapered fiber up to 2600 nm

Ces dernières années, des avancées considérables ont été obtenues dans le domaine des capteurs à fibres optiques, principalement grâce à l’élan des applications industrielles, de plus en plus diverses et nombreuses (monitoring de structures, surveillance, environnement, applications médicales, ….). Cette thèse concerne le domaine des antennes acoustiques SONAR en technologie « tout-optique » Dans ce travail, nous nous sommes intéressés à l’étude d’un capteur de contrainte longitudinale à fibre optique. La modulation de phase optique induite par la contrainte est démodulée par un interféromètre adaptatif basé sur le principe de l’holographie dynamique. Cet interféromètre permet, par essence, (i) le filtrage des perturbations basse fréquence de l’environnement, (ii) un fonctionnement en régime linéaire (iii) la démodulation d’un front d’onde complexe, type speckle issu d’une fibre optique multimode. L’holographie dynamique repose sur l’interaction entre deux ondes optiques dans un milieu non-linéaire. Pour notre application, le milieu non-linéaire retenu est un modulateur spatial de lumière adressé optiquement (OASLM) à 1,55 μm. Nous présentons tout d’abord nos travaux de conception, réalisation et caractérisation de l’interféromètre adaptatif. Nous démontrons ensuite un capteur de contrainte à fibre optique basé sur cet interféromètre. Nous étudions également l’augmentation de sensibilité du capteur par l’utilisation d’une fibre optique multimode. Nous discutons finalement nos résultats et le potentiel de la technologie étudiée au regard de l’application visée. / Fiber optic sensors are a key technology for future developments with a large field of applications ranging from structure health monitoring to medical applications. Due to its high compactness, its electromagnetic immunity and the low transmission losses in the telecom window, optical fibers are very promising for underwater acoustic waves detection. We present a method relying on adaptive holographic interferometry based on two beam coupling in an optically addressed spatial light modulator (OASLM). This method allows filtering the slow phase perturbations coming from the environment directly on the sensing optical fiber. In this work, we will first introduce the OASLM operating at 1,55 μm that we have manufactured and the realization of an adaptive holographic interferometer based on this component. Moreover, we will show that it is possible to associate this demodulation method with a multimode optical fiber to reach a better sensitivity. Finally, we will focus on sensors architectures to evaluate the benefit of this technology compared to conventional techniques.

No description available.

Ce travail de thèse porte sur l'étude de l'impact de la nanostructuration de la matière sur le comportement des fibres dopées Erbium en environnement radiatif tel que l'Espace. Cette étude est motivée par le fait qu'il n'existe pas de fibre dopée Erbium qualifiée pour le spatial, rendant l'AOFD indisponible pour ces applications, réduisant fortement l'intérêt de l'ensemble de la technologie WDM pour les satellites. Ainsi nous avons testé plusieurs fibres basées sur des technologies différentes dans le but d'évaluer leurs comportements sous radiations gamma. Nous avons ainsi défini un critère objectif pour la sélection des fibres dopées Erbium, et avons montré des éléments permettant de durcir des fibres co-dopées Aluminium en se basant uniquement sur des paramètres de conception. Ainsi, nous avons démontré une fibre durcie aux radiations à base de nanoparticules de silice dopées Erbium, montrant une perte de puissance de l'ordre de 1 dB en fin de mission typique d'un satellite. L'accent a également été mis sur la modélisation de l'AOFD en proposant un modèle évolué prenant en compte des effets non linéaires liés à la complexité de la spectroscopie de l'ion Erbium. Ce modèle a été complété par une prise en compte de l'effet des irradiations et de la guérison optique en utilisant un modèle de proche de celui développé par R. Chen. Nous avons pu noter la grande importance de l'effet de la guérison optique sur les performances de l'AOFD en fin de vie. / This thesis focuses on the impact of nanostructuration on the performance of Erbium Doped Fiber in severe environment like Space. This study is motivated by the fact that no on-the-shell Erbium Doped Fiber can satisfy the space requirement, disabling the availability of the AOFD and stongly limiting the interest of the WDM technology for satellites. Several fiber based on different technologies have been tested in order to check their behavior under gamma radiations. We have defined an objective criterion for the selection of erbium doped fibers, and showed elements for hardening aluminum co-doped fibers, based solely on design parameters. In this way, we brought to the fore a radiation hardened fiber, based on silica nanoparticles, exhibiting a power decrease of 1 dB after a typical space mission. We also focused on EDFA modeling by proposing an evolved model taking into account non-linear effects due to the complex spectroscopy of Erbium. This model is completed by including irradiation effects thanks to a model such as Chen's one. The photobleaching effect that has been found to be strong is also considered.

This masters thesis is focusing on the issue of passive optic access networks. It is dealing with the limiting factors for broadband connections, especially attenuation of fibre optics and dispersion. It is also dealing with most commonly used standards of passive optic networks. It clarifies the issue of wavelength-division multiplexing, its advantages and disadvantages, used standards, various types of components for the WDM-networks, their characteristics, application etc. In the practical part of the work you can find the measuring and diagnostics of the passive optic network EPON. It contains measuring by the direct method OLTS, measuring by the Pon Power Meter and optic reflectometer OTDR. At the end I am dealing with the measuring of splitter in the rate of 1:16.

This project describes the fundamental concepts and basic theory of polarization mode dispersion (PMD) in optical fibers. There are described basic the relation between Jones vectors and Stokes vectors, rotation matrices, the definition and representation of PMD vectors, the laws of infinitesimal rotation. After the introduction the first conception with bases of polarization mode dispersion (PMD) in optical fibers, they have become an important body of knowledge basic for the design of high-capacity optical communication systems. PMD effects are linear electromagnetic propagation phenomena occurring in so-called “single-mode“fibers. Despite their name, these fibers support two modes of propagation distinguished by their polarization. Because of optical birefringence in the fiber, the two modes travel with different group velocities, and the random change of this birefringence along the fiber length results in random coupling between the modes. With current practical transmission technology the resulting PMD phenomena lead to pulse distortion and system impairments that limit the transmission capacity of the fiber. I describe different ways of measuring PMD in optical fibre, PMD compensation techniques and analyse PMD results in optical fibres.

Electric grid as we now it has been without significant change for a long time. Along with the human population grows demand for electricity, which leads to need to create more energy. Bigger interest is in ecology and use of renewable sources, although these do not have constant output which often stresses the grid. These problems are to be solved by smart grids. Smart grids are capable of adjusting energy generation to immediate demand including renewable sources to compensate energy fluctuations in grid. They provide demand response and other applications interesting for end users. Smart grids are combination of achievements in energy, informatics and communication technology. Communication, which is key part of smart grids, has to met certain requirements and can be executed by various technologies. There are described various communication technologies and a design concept of data communication in this paper.

This master thesis deals with problematics of information transmission trough optical fiber and spreading of the electromagnetic field at wavelengths of light. There are analyzed characteristics of the optical signal, and described methods of measuring wavelength of the optical signal power and noise level of the useful signal. Another examined parameter is OSNR at the input and on the output of the optical fiber amplifier EFDA.