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Proceedings Paper

Optical nonlinearities induced by laser radiation in some fatty acids from the biological membrane
Author(s): Mihaela A. Ghelmez; Maria Honciuc; Livia Sterian; Cristian Gheorghe
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Paper Abstract

In this paper, we present a study of pure arachidonic acid, arachidic acid, other fatty acids (FA) and mixtures with cholesterol (Ch) in different ratio of compounds, having smectic C liquid crystal (LC) properties. Very thin systems (`membranes') of FA and mixtures, manufactured by us, were subjected to some electrical measurements, that show a new distribution, induced by Ch, of the space charge in the system. The FA and mixtures' samples were also sandwiched between two glass plates of transparent SnO2 electrodes and studied under dc and ac electric fields. The hysteresis curves of the current versus the applied voltage exhibited a nonlinear dielectric feature and a negative resistance. We studied the change of the fundamental IR and second harmonic pulsed beam of a Nd3+ glass laser, in the time domain, after passing through our samples; the optical output power of a He-Ne laser beam ((lambda) equals 6328 angstroms, Pmax equals 20 mW), from the LC cells situated between parallel and crossed polarizers was registered. A nonlinear optical behavior of the samples and some memory effects were emphasized. Also a correlation between the electric and optical nonlinearity of the samples seems to be possible.

Paper Details

Date Published: 4 January 1999
PDF: 11 pages
Proc. SPIE 3565, Thermal Therapy, Laser Welding, and Tissue Interaction, (4 January 1999); doi: 10.1117/12.335795
Show Author Affiliations
Mihaela A. Ghelmez, Politehnica Univ. Bucharest (Romania)
Maria Honciuc, Politehnica Univ. Bucharest (Romania)
Livia Sterian, Clinical Hospital of Stomatology (Romania)
Cristian Gheorghe, Fundeni Hospital Bucharest (Romania)

Published in SPIE Proceedings Vol. 3565:
Thermal Therapy, Laser Welding, and Tissue Interaction
Stephen G. Bown; Guy P. Delacretaz; Guilhem Godlewski M.D.; Gerhard J. Mueller; Roberto Pini; Hans-Dieter Reidenbach; Rudolf W. Steiner; Lars Othar Svaasand; Karl-Goran Tranberg, Editor(s)

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