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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Structural and transport properties in some superionic conductors, acousto-optic materials and titanite frameworks

Kennedy, Kevin Martin January 1997 (has links)
No description available.
2

Optical Filter Design: Gain Analysis and Tolerance Analysis

Vandrasi, Vivek 2010 August 1900 (has links)
Three components, gain analysis, tolerance analysis in-depth, and a brief non- linearity analysis, are presented. In the first component, the effects of an Erbium doped waveguide amplifier in a microring are investigated using a time domain simulation. Methods to simulate the gain versus average input signal power in the microring are studied, given that it has a long lifetime compared to the short delay time of the microring. The methods are based on the dependence of the gain on the power of the signal being fed to the ring. An algorithm is proposed to perform a thorough tolerance analysis on any optical circuit with respect to any optical parameter. The algorithm, based on Monte Carlo Simulation, is implemented on a complex optical circuit that is designed to obtain a bandpass filter response of given specifications. It is also tested on similar designs for a comparative study between them. The parameters and the structure of the designs used for the analysis are presented in detail. The results are presented in terms of the yield with respect to the parameter being varied, against their tolerance value. Algorithms for studying the effects of two types of non-linearities are presented. The Kerr nonlinearity and the two-photon absorption are included in the bandpass filter designs used for the tolerance analysis. The algorithms are based on the power circulating in different regions of the circuit under consideration. The variation in the original response because of the loss due to nonlinearity is observed and analyzed for different power levels of the input signal.
3

Ótica e tecnologia de filmes finos / Optical and technology of thin films

Araujo, Jeremias Francisco de 14 June 1983 (has links)
O objetivo deste trabalho é desenvolver a tecnologia de produção de filmes finos de precisão, de materiais dielétricos e/ou metálicos sobre componentes óticos de precisão. Para tal, cálculos computacionais de filmes finos foram desenvolvidos, tendo como finalidade projetarmos teoricamente qualquer tipo de camadas finas. As características dos filmes são mostradas graficamente ou em forma de tabela. A tecnologia de evaporação em alto vácuo de materiais tais como SiO2, Ti2O3, MgO, MgF2 e criolita (Na3AlF6), foi implantada no laboratório de filmes finos do DFCM. Alguns desses materiais, os óxidos, foram evaporados pioneiramente no Brasil neste trabalho. As camadas estudadas foram: Anti-refletoras com uma, duas e três camadas, espelhos de alta refletividade para lasers, filtros interferencial, filtros passa banda, separadores de feixes, etc. Tendo como ponto de partida os cálculos computacionais desenvolvidos e a tecnologia de evaporação implantada, algumas camadas de filmes finos de utilidade em ótica foram finalmente produzidas. A caracterização dos filmes finos por nós produzidos foi feita por medida da reflexão ou transmissão na região do infravermelho próximo, visível e ultravioleta, sendo para tal utilizado o espectrofotometro Cary 17. Estes espectros mostram boa concordância com os resultados teóricos obtidos. / In this work we developed the technology of production of precision metallic and/or dielectric thin films evaporated on optical components. Numerical calculations of the characteristics of the films was developed allowing the knowledge of the reflectance spectra of the coatings before the evaporation, saving the cost of test by evaporation. The high vacuum evaporation technique of materials like SiO2, Ti2O3, MgO, Al2SO3, MgF2, and criolite (Na3AlF6) was implanted in the thin film laboratory of the DFCM. Some of this materials was evaporated by the first time in Brazil in this work. The coatings studied was: Anti-reflecting coatings of one, two and three layers, high reflecting mirrors for lasers, band pass filter, high and low pass filters. Starting with the numerical calculations some of the most frequently used coating in optics was projected and finally produced in the laboratory. These films were characterized by the spectra of reflection obtained with the spectrometer Cary 17. The characteristics of the films produced agree very well with the calculations.
4

Advanced Silicon Microring Resonator Devices for Optical Signal Processing

Masilamani, Ashok Prabhu Unknown Date
No description available.
5

Ótica e tecnologia de filmes finos / Optical and technology of thin films

Jeremias Francisco de Araujo 14 June 1983 (has links)
O objetivo deste trabalho é desenvolver a tecnologia de produção de filmes finos de precisão, de materiais dielétricos e/ou metálicos sobre componentes óticos de precisão. Para tal, cálculos computacionais de filmes finos foram desenvolvidos, tendo como finalidade projetarmos teoricamente qualquer tipo de camadas finas. As características dos filmes são mostradas graficamente ou em forma de tabela. A tecnologia de evaporação em alto vácuo de materiais tais como SiO2, Ti2O3, MgO, MgF2 e criolita (Na3AlF6), foi implantada no laboratório de filmes finos do DFCM. Alguns desses materiais, os óxidos, foram evaporados pioneiramente no Brasil neste trabalho. As camadas estudadas foram: Anti-refletoras com uma, duas e três camadas, espelhos de alta refletividade para lasers, filtros interferencial, filtros passa banda, separadores de feixes, etc. Tendo como ponto de partida os cálculos computacionais desenvolvidos e a tecnologia de evaporação implantada, algumas camadas de filmes finos de utilidade em ótica foram finalmente produzidas. A caracterização dos filmes finos por nós produzidos foi feita por medida da reflexão ou transmissão na região do infravermelho próximo, visível e ultravioleta, sendo para tal utilizado o espectrofotometro Cary 17. Estes espectros mostram boa concordância com os resultados teóricos obtidos. / In this work we developed the technology of production of precision metallic and/or dielectric thin films evaporated on optical components. Numerical calculations of the characteristics of the films was developed allowing the knowledge of the reflectance spectra of the coatings before the evaporation, saving the cost of test by evaporation. The high vacuum evaporation technique of materials like SiO2, Ti2O3, MgO, Al2SO3, MgF2, and criolite (Na3AlF6) was implanted in the thin film laboratory of the DFCM. Some of this materials was evaporated by the first time in Brazil in this work. The coatings studied was: Anti-reflecting coatings of one, two and three layers, high reflecting mirrors for lasers, band pass filter, high and low pass filters. Starting with the numerical calculations some of the most frequently used coating in optics was projected and finally produced in the laboratory. These films were characterized by the spectra of reflection obtained with the spectrometer Cary 17. The characteristics of the films produced agree very well with the calculations.
6

Filtro de interferência variável e descrição de uma aplicação: dispositivo multicanal espectral para análise ambiental. / Variable interference filter and description of an application: multichannel spectral device for environmental analysis.

Celso Manoel da Silva 05 February 2010 (has links)
O presente trabalho apresenta o desenvolvimento de um método de obtenção e a caracterização de filtros ópticos de interferência de banda passante variável que, constituídos por refletores dielétricos multicamadas de filmes finos intercalados por cavidades de Fabry- Perot não planares com espessuras linearmente variáveis, apresentam a propriedade do deslocamento linear da transmitância máxima espectral em função da posição, isto é, um Filtro de Interferência Variável (FIV). Este método apresenta novas e abrangentes possibilidades de confecção de filtros ópticos de interferência variável: lineares ou em outras formas desejadas, de comprimento de onda de corte variável (passa baixa ou alta) e filtros de densidade neutra variável, através da deposição de metais. A primeira etapa do trabalho foi o projeto e a construção de um filtro óptico convencional, de um comprimento de onda central, com camadas homogêneas. A etapa seguinte foi, com base na teoria espectrométrica, promover a variação das espessuras das camadas em um perfil inclinado e linear. Para tanto, de acordo com os requisitos de projeto, foram feitas adaptações em uma evaporadora por e-Beam (elétron-Beam), acrescentando um obliturador mecânico especialmente projetado, ajustando parâmetros de técnicas de deposição e caracterizando o perfil inclinado de um filme depositado para ajustar o obliturador. E, ao final destas etapas, foi projetado e construído o FIV especificado. Também é descrita uma possível aplicação do FIV: um dispositivo multicanal espectral para análise ambiental, e, dentre muitas, outras podem ser mencionadas: sistemas Lab-on-Chip, biosensores, detectores chip-sized, espectrometria de fluorescência on-chip, detectores de deslocamento de comprimento de onda, sistemas de interrogação e etc. / This work presents the development of a method to obtain and characterize a variable interference optical bandpass filter, made up of a number of thin films forming dielectrical reflectors intercalated by non flat Fabry-Perot cavities whose thickness variates linearly. These filters present the propriety of a linear variation in the maximum spectral transmittance as a function of the position in the filter, for this reason this is called Variable Interference Filter (VIF). This method allows of manufacturing linear interference filters or any other function disered, with variable cut wavelength (low or high pass) and variable neutral density filters by means of metallic depositions. The first step in this work was to design and built a conventional filter, with homogeneous layers and a fixed central wavelength. The following step was, using spectrometric theory basis, introduce the variation in the thickness of the layers in a linear inclined outline. Accordingly with the design requirements, it was made some adaptations in an e-beam evaporator (electron-beam), adding a mechanical obliterator adjusted with series of depositions and characterizations of a single layers in order to find a linearly inclined outline. In the end of this step it was designed and built the specified VIF. It is also described a possible application of this VIF: a multichannel spectral device for environmental analysis. Between many applications, others can be cited, such as: Lab-on-Chip systems, biosensors chip-sized detectors, on-chip fluorescence spectrometry, shift wavelength detectors, interrogation systems, etc.
7

Filtro de interferência variável e descrição de uma aplicação: dispositivo multicanal espectral para análise ambiental. / Variable interference filter and description of an application: multichannel spectral device for environmental analysis.

Silva, Celso Manoel da 05 February 2010 (has links)
O presente trabalho apresenta o desenvolvimento de um método de obtenção e a caracterização de filtros ópticos de interferência de banda passante variável que, constituídos por refletores dielétricos multicamadas de filmes finos intercalados por cavidades de Fabry- Perot não planares com espessuras linearmente variáveis, apresentam a propriedade do deslocamento linear da transmitância máxima espectral em função da posição, isto é, um Filtro de Interferência Variável (FIV). Este método apresenta novas e abrangentes possibilidades de confecção de filtros ópticos de interferência variável: lineares ou em outras formas desejadas, de comprimento de onda de corte variável (passa baixa ou alta) e filtros de densidade neutra variável, através da deposição de metais. A primeira etapa do trabalho foi o projeto e a construção de um filtro óptico convencional, de um comprimento de onda central, com camadas homogêneas. A etapa seguinte foi, com base na teoria espectrométrica, promover a variação das espessuras das camadas em um perfil inclinado e linear. Para tanto, de acordo com os requisitos de projeto, foram feitas adaptações em uma evaporadora por e-Beam (elétron-Beam), acrescentando um obliturador mecânico especialmente projetado, ajustando parâmetros de técnicas de deposição e caracterizando o perfil inclinado de um filme depositado para ajustar o obliturador. E, ao final destas etapas, foi projetado e construído o FIV especificado. Também é descrita uma possível aplicação do FIV: um dispositivo multicanal espectral para análise ambiental, e, dentre muitas, outras podem ser mencionadas: sistemas Lab-on-Chip, biosensores, detectores chip-sized, espectrometria de fluorescência on-chip, detectores de deslocamento de comprimento de onda, sistemas de interrogação e etc. / This work presents the development of a method to obtain and characterize a variable interference optical bandpass filter, made up of a number of thin films forming dielectrical reflectors intercalated by non flat Fabry-Perot cavities whose thickness variates linearly. These filters present the propriety of a linear variation in the maximum spectral transmittance as a function of the position in the filter, for this reason this is called Variable Interference Filter (VIF). This method allows of manufacturing linear interference filters or any other function disered, with variable cut wavelength (low or high pass) and variable neutral density filters by means of metallic depositions. The first step in this work was to design and built a conventional filter, with homogeneous layers and a fixed central wavelength. The following step was, using spectrometric theory basis, introduce the variation in the thickness of the layers in a linear inclined outline. Accordingly with the design requirements, it was made some adaptations in an e-beam evaporator (electron-beam), adding a mechanical obliterator adjusted with series of depositions and characterizations of a single layers in order to find a linearly inclined outline. In the end of this step it was designed and built the specified VIF. It is also described a possible application of this VIF: a multichannel spectral device for environmental analysis. Between many applications, others can be cited, such as: Lab-on-Chip systems, biosensors chip-sized detectors, on-chip fluorescence spectrometry, shift wavelength detectors, interrogation systems, etc.
8

Optoelectronic mixing in heterojunction bipolar transistors

Liu, Chin Pang January 2000 (has links)
No description available.
9

Simulering av filtrerade skärmfärger

Andersson, Christian January 2005 (has links)
<p>This report present a working model for simulation of what happens to colors displayed on screens when they are observed through optical filters. The results of the model can be used to visually, on one screen, simulate another screen with an applied optical filter. The model can also produce CIE color difference values for the simulated screen colors. The model is data driven and requires spectral measurements for at least the screen to be simulated and the physical filters that will be used. The model is divided into three separate modules or steps where each of the modules can be easily replaced by alternative implementations or solutions. Results from tests performed show that the model can be used for prototyping of optical filters even though the tests of the specific algorithms chosen show there is room for improvements in quality. There is nothing that indicates that future work with this model would not produce better quality in its results.</p> / <p>Denna rapport presenterar en fungerande modell för att optiskt simulera vad som händer med färger på bildskärmar då skärmarna betraktas genom optiska filter. Resultat från modellen består av information som kan användas för visuell simulering av en skärm med applicerat filter på en annan visande skärm. Förutom ren bilddata kan modellen även producera färgskillnadsvärden som kan härledas från CIE 1931 XYZ-koordinater. Modellen är datadriven och kräver initiala mätningar på minst den skärm som ska simuleras samt filter. Hela modellen är uppdelad i tre separata moduler eller steg där de olika delarna lätt kan bytas ut för alternativa algoritmer och lösningar. Resultat från undersökningar visar på att modellen går att använda för prototypning även om de, för arbetet specifikt, valda algoritmerna för de olika stegen i undersökningen visar på brister i kvalité. Det finns inget som visar att framtida arbete där andra algoritmer valts inte skulle kunna prestera ännu bättre resultat.</p>
10

Micro-optic-spectral-spatial-elements (mosse)

Mehta, Alok Ajay 01 January 2007 (has links)
Over a wide range of applications, optical systems have utilized conventional optics in order to provide the ability to engineer the properties of incident infra-red fields in terms of the transmitted field spectral, spatial, amplitude, phase, and polarization characteristics. These micro/nano-optical elements that provide specific optical functionality can be categorized into subcategories of refractive, diffractive, multi-layer thin film dichroics, 3-D photonic crystals, and polarization gratings. The feasibility of fabrication, functionality, and level of integration which these elements can be used in an optical system differentiate which elements are more compatible with certain systems than others. With enabling technologies emerging allowing for a wider range of options when it comes to lithographic nano/micro-patterning, dielectric growth, and transfer etching capabilities, optical elements that combine functionalities of conventional optical elements can be realized. Within this one class of optical elements, it is possible to design and fabricate components capable of tailoring the spectral, spatial, amplitude, phase, and polarization characteristics of desired fields at different locations within an optical system. Optical transmission filters, polarization converting elements, and spectrally selective reflecting components have been investigated over the course of this dissertation and have been coined  MOSSE,' which is an acronym for micro-optic-spectral-spatial-elements. Each component is developed and fabricated on a wafer scale where the thin film deposition, lithographic exposure, and transfer etching stages are decoupled from each other and performed in a sequential format. This facilitates the ability to spatially vary the optical characteristics of the different MOSSE structures across the surface of the wafer itself.

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