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Proceedings Paper

Experimental data and modeling of X(2) temporal stability of poled chromophore-doped sol-gel materials
Author(s): Helene Goudket; Michael Canva; Yves Levy; Frederic Chaput; Jean-Pierre Boilot
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Paper Abstract

The relaxation of the second-order nonlinearity of poled chromophore-doped sol-gel thin films has been studied at different temperatures between 63 degree(s)C and 82 degree(s)C (poling temperature: 90 degree(s)C). The process has been monitored through the variations of second harmonic generation (SHG) induced in the poled film by a pulsed nanosecond Nd:YAG laser (1064 nm). The SHG decay curves have then been fitted to bi-exponentials and Kohlrausch, Williams and Watts (KWW) stretched exponentials. The better quality of the KWW fits involves that this model is more appropriate than the bi- exponential model to describe chromophore relaxation in sol- gel thin films, as has been observed for classical all- organic polymers. A numerical analysis of the KWW parameters enables a better understanding of the function meaning. The time constants obtained with both models have been logarithmically plotted in function of temperature. An Arrhenius-type linear fit has been adjusted to this representation, and a value of the relaxation time extrapolated at room temperature. The bi-exponential model yields time constants of 26 and 110,000 years, while the KWW model extrapolates to an 87 years' second-order nonlinearity lifetime with a corresponding activation energy of 49 kcal.mol-1. Decay data gathered at room temperature over a period of 17 months can be fitted with both models and yield time constants of 14 days and 13 years for the bi- exponential, and of 115 days for the stretched exponential. The extrapolated KWW fit can be corrected with a factor of 0.58 to adjust the experimental data. This reveals the possible existence of a very rapid relaxation (less than a minute for our measurement temperatures) that was not measured. Nonetheless, our work shows that second-order nonlinearity in poled chromophore-doped sol-gel thin films is stable for more than a year. This is an encouraging result for future applications in telecom industry, especially as this feature has not yet been studied and optimized in terms of material synthesis.

Paper Details

Date Published: 7 December 2001
PDF: 8 pages
Proc. SPIE 4461, Linear and Nonlinear Optics of Organic Materials, (7 December 2001); doi: 10.1117/12.449828
Show Author Affiliations
Helene Goudket, CNRS and Univ. d'Orsay-Paris XI (France)
Michael Canva, CNRS and Univ. d'Orsay-Paris XI (France)
Yves Levy, CNRS and Univ. d'Orsay-Paris XI (France)
Frederic Chaput, CNRS and Ecole Polytechnique (France)
Jean-Pierre Boilot, CNRS and Ecole Polytechnique (France)

Published in SPIE Proceedings Vol. 4461:
Linear and Nonlinear Optics of Organic Materials
Manfred Eich; Mark G. Kuzyk, Editor(s)

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