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Doctoral Thesis
DOI
10.11606/T.76.2005.tde-23062005-140637
Document
Author
Full name
Newton Martins Barbosa Neto
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2005
Supervisor
Committee
Zilio, Sergio Carlos (President)
Borissevitch, Iouri
Catunda, Tomaz
Moreira, Wania da Conceição
Vieira Junior, Nilson Dias
Title in Portuguese
"Estudo e desenvolvimento de limitadores ópticos"
Keywords in Portuguese
Absorção saturada reversa
Limitação óptica
Limitador de múltiplas passagens
Porfirina
Abstract in Portuguese
Neste trabalho, com objetivo de desenvolvermos dispositivos de limitação óptica, estudamos o processo de absorção de estado excitados em um grupo de tetrapiridil porfirinas com diferentes substituintes centrais (2H+, Zn2+, Ni2+, Cu2+). Para isso utilizamos a técnica de varredura – Z com pulsos de femto e picossegundos bem como com trem de pulsos. Desta forma, determinamos a dinâmica de absorção de estados excitados, para estas moléculas, obtendo parâmetros espectroscópicos tais como tempo de cruzamento intersistema, e as seções de choque de absorção dos primeiros estados excitados singleto e tripleto. Além disso, visando aproveitar os processos ópticos acumulativos de alguns materiais não lineares, em aplicação de limitação óptica, desenvolvemos uma nova geometria óptica denominada de limitador óptico de múltiplas passagens, a qual utiliza dois espelhos esféricos confocais e um espelho plano posicionado paralelamente a linha que une os espelhos esféricos.
Title in English
Study and development of optical limiters
Keywords in English
Multipass optical limiter
Optical limiting
Porphyrins
Reverse saturable absorption
Abstract in English
In this work, aiming to develop optical limiting devices, we have studied excited state absorption process in a group of tetrapyridyl porphyrins with different central substitutes (2H+, Zn2+, Ni2+, Cu2+). We have employed Z-scan technique with femto and picosecond pulses as well as with pulse trains to determine the excited state absorption dynamics and obtain some spectroscopic parameters like intersystem crossing time and triplet and singlet excited state absorption cross-sections. Moreover, we have developed a new geometry for an optical limiter, named multipass optical limiter. It is formed by two confocal spherical mirrors together with a plane mirror placed in parallel with the line joining them.
 
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tesenewton.pdf (2.24 Mbytes)
Publishing Date
2005-08-04
 
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