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Master's Dissertation
DOI
10.11606/D.43.1998.tde-13082002-100046
Document
Author
Full name
Marcelo Martinelli
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1997
Supervisor
Committee
Horowicz, Ricardo Josue (President)
Lejbman, Iuda Dawid Goldman Vel
Vieira Junior, Nilson Dias
Title in Portuguese
Medida de efeitos óticos não-lineares por reflexão de luz polarizada.
Keywords in Portuguese
efeito Kerr ótico
RZ-scan
varredura Z
Z-scan
Abstract in Portuguese
Apresentamos neste trabalho uma nova técnica de medida dos termos não-lineares do coeficiente de absorção (beta) e do índice de refração (n_2). Esta nova técnica, denominada Varredura Z de Reflexão Inclinada, aumenta a sensibilidade da Varredura Z de Reflexão em cerca de 30 vezes pelo emprego de um feixe polarizado com incidência inclinada sobre a amostra em estudo. Para uma polarização paralela ao plano de incidência, temos um máximo de sensibilidade nas proximidades do ângulo de Brewster para materiais transparentes, ou do ângulo de mínima reflexão em materiais absortivos. Conseguimos por este método medir variações do índice de refração da ordem de 10^{-4} em absorvedores saturáveis (Aluminato de Gadolínio - GdAlO_{3}:Cr^{+3}). Tais medidas não seriam possíveis sem o aumento obtido na sensibilidade e o uso de uma alta resolução no sistema de aquisição (melhor que 0,1% em intensidade).
Title in English
Measurement of non-linear optical effects through the reflection of polarized light.
Keywords in English
optical Kerr effect
Abstract in English
We present in this work a new technique that we developed for the measurements of nonlinear coefficients of the absorption (beta) and from the refractive index (n_2). The use of a polarized beam in this new technique (Reflection Z-Scan with Inclined Incidence) increases the set-up sensibility of the conventional RZ-Scan measurement in 30 times. For parallel polarization of the beam to the incidence plane, we can see an increase in the measurement sensibility as the incident light angle approaches the Brewster angle for transparent materials, or the minimum reflection angle for an absorbing material. We have measured changes in the refractive index as small as 10^{-4} in saturable absorber (Gadolinium Aluminate - GdAlO_{3}:Cr^{+3}). Such measurements would not be possible without the development of the sensitivity enhancement achieved by this technique and a high amplitude resolution on the data acquisition system, as small as 0.1%.
 
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Mestrado.pdf (971.14 Kbytes)
Publishing Date
2002-08-23
 
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