Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (leaves 114-120).

Thesis (M.S.)--University of North Texas, Dec., 2009. / Title from title page display. Includes bibliographical references.

Thesis (MS)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Kevin S. Repasky. Includes bibliographical references (leaves 61-62).

Thesis (MS)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Kevin S. Repasky. Includes bibliographical references (leaves 49-51).

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xiv, 166 p.; also includes graphics (some col.) Includes bibliographical references (p. 156-166).

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Made available in DSpace on 2014-10-09T12:33:39Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:37Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:33:39Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:37Z (GMT). No. of bitstreams: 0 / Os aerossóis e nuvens desenvolvem um papel muito importante nos processos climáticos terrestres por meio das suas contribuições diretas e indiretas no balanço radiativo da atmosfera. A dificuldade na previsão dos processos de mudanças climáticas estão associadas às incertezas na distribuição e propriedades dos aerossóis e nuvens, assim como em suas interações em escala global. Tendo como principal objetivo desenvolver estudos que ajudem na diminuição dessas incertezas, a NASA, em parceria com a agência espacial francesa CNES, desenvolveu a missão do Satélite CALIPSO, que possui a bordo um sistema Lidar denominado CALIOP capaz de estudar o perfil e a distribuição vertical dos aerossóis e nuvens e os processos de interação entre eles. Uma vez que as propriedade ópticas medidas pelo CALIOP são recuperadas utilizando um complexo conjunto de algoritmos, torna-se necessário o desenvolvimento de estudos e metodologias de validação para inferir qual a acurácia das medidas desse sistema. Nesse contexto, foi desenvolvida uma metodologia de avaliação e validação dos valores de Razão Lidar utilizados a priori pelos algoritmos do CALIOP utilizando dois instrumentos de sensoriamento remoto instalados em solo, um sistema Lidar de retroespalhamento elástico instalado no IPEN - São Paulo e o fotômetro solar da rede AERONET instalado em cinco diferentes localidades, Rio Branco - Acre (RB), Alta Floresta - Mato Grosso (AF), Cuiabá - Mato Grosso (CB), Campo Grande - Mato Grosso do Sul (CG) e São Paulo - São Paulo (SP). Foram determinados os dias de medidas correlativas entre os sistemas em solo e o CALIOP e analisados os dados para os dias de medidas com condições livre de nuvens e com trajetórias de massas de ar se deslocando das regiões de medidas do satélite para as regiões de medidas pelos instrumentos fixos. Foram calculados novos valores de Razão Lidar obtidos pelo Modelo Aeronet/Caliop (Modelo A/C) proposto. Esses valores mostraram-se coerentes com aqueles utilizados inicialmente pelo algoritmo do sistema CALIOP. Realizando uma comparação quantitativa, obteve-se uma diferença percentual de 2,17 ± 30,12%, esse valor mostra-se compatível com outros valores obtidos na literatura de validação desse sistema Lidar a bordo do Satélite CALIPSO. Essa subestimação nos valores de Razão Lidar utilizados pelo CALIOP pode estar ocorrendo devido um problema no processo de calibração dos dados do sistema CALIOP, uma vez que o território brasileiro se encontra na região da Anomalia do Atlântico Sul (SAA). A diferença percentual dos valores de Razão Lidar utilizados pelo CALIOP com aqueles obtido por meio de medidas com o sistema Lidar do IPEN forneceram valores de 2,34 ± 17,53%, demonstrando que o modelo de validação proposto é aceitável e acurácia nos valores de Razão Lidar utilizados a priori pelo CALIOP está dentro das margens de incerteza de 30%. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Silicon photonics is a powerful technological platform that has advanced with gigantic steps during the past 20 years. Its applications range from the nanoscale, with biosensing and spectroscopy, all the way to the macroscale, with optical fiber communications and on-chip Lidar. However, its commercialization is still hindered by the lack of a cost-effective and automatable chip packaging approaches. At the same time, the current multiplexing techniques to increase the bandwidth density of optical communication networks are hitting their theoretical capacity limits. This has pushed the community to look for additional spatial data transmission paths through a common optical fiber. At the smaller end of the size scale, the controlled self-assembly of nanoparticles is the holy grail of nanotechnologists around the globe. Great advances towards this goal have been demonstrated, but most of the time it is hard to simultaneously control the many variables involved in the self-assembly processes. Silicon photonics and compatible wave guiding techniques are the ideal platform to address these issues thanks to their ability of controlling light in the nanoscale. Regarding the macroscale, this dissertation presents approaches based on micro 3D printing to overcome the silicon photonics packaging bottleneck and to access additional spatial channels to increase the bandwidth density of optical communication channels. Section 2.2 presents the plug-and-play coupling of fibers to waveguides, where a 3D printed optical-mechanical micro connector is defined directly on top of a silicon photonics chip. This connector has such a relaxed alignment tolerance, that even the coarse precision of industrial automated assembly tools is enough to automatically couple a fiber to the waveguide in a robust and passive way. Section 2.3 shows another 3D printed micro coupler design. This coupler optically bridges between the higher order modes of a multimode silicon waveguide and those of a few-mode fiber. These higher order modes can carry different streams of information at the same wavelength, effectively increasing the amount of data transmitted through the same physical channel. Regarding the nanoscale world, there is a very popular but not completely well understood self-assembly technique called evaporative self-assembly. For the past couple of decades scientists have been trying to harness it to deposit controlled patterns of nanostructures (ranging from inorganic nanoparticles to biological elements). The problem with this technique is that several of the physical variables involved in the evaporative self-assembly process are coupled to each other, making it difficult to precisely control the particle deposition. Section 3.3 shows a way of depositing a periodic pattern of gold nanoparticle clusters along the top of a silicon photonics waveguide by assisting the evaporative self-assembly process with optofluidic transport of particles. The particle trapping and transport along a waveguide is possible thanks to the strong optical forces in the immediate vicinity of the waveguide core. With this approach, the evaporative self-assembly deposition pattern periodicity can be controlled simply by tuning only one knob: the input laser power.

LIDAR is the optical equivalent of RADAR. A LIDAR facility has been established at Rhodes University using a flashlamp-pumped dye laser as the transmitter and a photomultiplier tube at the focus of a searchlight mirror as the receiver. The setting up of the receiver and transmitter as well as the design and construction of the photon counting electronics is described. The LIDAR has been used to measure aerosol scattering ratios and temperature profiles in the stratosphere and these results are presented with the algorithms and software used to reduce the data. Finally some recommendations are made for future work