“…After deposition, the preform is submitted to thermo-chemical processes, resulting in a totally transparent and consolidated preform. Figure 1 illustrates the instrumentation of VAD deposition stage [4].…”
Abstract.A novel fabrication method of elliptical-shaped preforms for polarization-maintaining fibers, developed using the VAD technology and based on the variation of the perform rotation velocity from zero to a maximum velocity in repeated cycles of 180°, allows modifying and controlling the preform geometry by choosing the process parameters, such as the maximum rotation velocity and the delay time on zero velocity positions. The effect of each process variable was studied through a mathematical modeling and simulation of the methodology, comprising a simplified model of the soot deposition process. Results demonstrated that preforms with high elUipticity can be obtained by increasing the delay time or decreasing the maximum rotation velocity. It was also observed that the effect of the delay time is more noticeable on the preform geometry than the contribution of maximum velocity. These facts were confirmed when compared to real deposition results, using a VAD chamber with gases fluxes set to l.SSxW^ mVs (SiCU) and CSxlO"*^ mVs (GeCl4), and setting the burner-target angle to a high deposition rate condition. It is expected that the improvement of the mathematical model can be very useful in order to determine the process conditions necessary to achieve any desired preform geometry, even before the deposition stage.
“…After deposition, the preform is submitted to thermo-chemical processes, resulting in a totally transparent and consolidated preform. Figure 1 illustrates the instrumentation of VAD deposition stage [4].…”
Abstract.A novel fabrication method of elliptical-shaped preforms for polarization-maintaining fibers, developed using the VAD technology and based on the variation of the perform rotation velocity from zero to a maximum velocity in repeated cycles of 180°, allows modifying and controlling the preform geometry by choosing the process parameters, such as the maximum rotation velocity and the delay time on zero velocity positions. The effect of each process variable was studied through a mathematical modeling and simulation of the methodology, comprising a simplified model of the soot deposition process. Results demonstrated that preforms with high elUipticity can be obtained by increasing the delay time or decreasing the maximum rotation velocity. It was also observed that the effect of the delay time is more noticeable on the preform geometry than the contribution of maximum velocity. These facts were confirmed when compared to real deposition results, using a VAD chamber with gases fluxes set to l.SSxW^ mVs (SiCU) and CSxlO"*^ mVs (GeCl4), and setting the burner-target angle to a high deposition rate condition. It is expected that the improvement of the mathematical model can be very useful in order to determine the process conditions necessary to achieve any desired preform geometry, even before the deposition stage.
“…Este processo é uma combinação das técnicas de deposição do processo OVD, MCVD (processo "soot") e da técnica de deposição axial no processo de deposição direta, Tomaru (1982), Niizeki (1985), Li (1985), Suzuki (1998).…”
Section: Técnica De Deposição Axial a Fase Vapor (Vad)unclassified
Ao meu orientador Prof. Dr. Carlos K. Suzuki, pela escolha do tema e pela orientação segura ao longo do desenvolvimento deste trabalho. Agradeço também pelas oportunidades criadas de interação com especialistas internacionais, na área de deposição axial fase vapor (VAD), para síntese de nanovidros, o que permitiu um aprofundamento no tema. Agradeço também pela valiosa chance que me foi concedida pelo orientador em desenvolver experimentos no SPring-8, Japão.A Eduarno Ono, pela amizade, dedicação, incansável ajuda, e pela inestimável colaboração na análise, redação e revisão deste trabalho.Ao Raul Cuevas, pelas discussões, sugestões e colaboração em todos os estágios de análise dos dados, que em muito contribuíram no desenvolvimento deste trabalho.
“…Neste contexto, o Laboratório de Quartzo e Dispositivos Fotônicos (LIQC) da FEM-UNICAMP possui o know-how e tecnologia necessários para a fabricação de preformas de sílica para fibras ópticas través do método "Vapor-phase Axial Deposition" (VAD), sendo a única instalação capacitada em todo o hemisfério sul. Esta iniciativa, iniciada em 1996, propiciou o estudo de metodologias inovadoras para a obtenção de preformas para fibras convencionais e especiais, bem como dispositivos ópticos de alta precisão (Suzuki 1998).…”
Este trabalho não poderia ser terminado sem a ajuda de diversas pessoas às quais presto minha homenagem: Ao Prof. Dr. Carlos Kenichi Suzuki, não somente pela orientação, mas principalmente pela credibilidade e confiança atribuídas ao meu trabalho, bem como pelas oportunidades oferecidas ao longo de toda a minha graduação.Ao Dr. Eduardo Ono, pelo grande auxílio e pelas discussões que muito auxiliaram no desenvolvimento do projeto.
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