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Optical Engineering

Modeling ion exchange in glass with concentration-dependent diffusion coefficients and mobilities
Author(s): Alexandru I. Lupascu; Antoine P. Kevorkian; Thierry Boudet; Francoise Saint-Andre; Dominique Persegol; Michel Levy
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Paper Abstract

Multimode buried waveguides made in silicate glass by fieldassisted ion exchange present very asymmetric profiles. We show how this phenomenon originates in the large dependence of the kinetics on the local ion concentrations. For this purpose, we derive an interdiffusion equation that includes the effects of concentration-dependent diffusion coefficients and mobilities. We show how to deduce this dependence from measurements on ion-diffused samples. The maximum concentration of the incoming ions is computed from surface equilibrium conditions and is used in the interdiffusion equation as a limiting parameter for coefficient variations. To control the model accuracy for surface as well as buried waveguides, we measure ion profiles with three independent methods: M-lines, scanning electron microscopy, and near-field refractometry. When applied to Ag+-Na+ exchange in silicate glass, the model yields theoretical estimations in good agreement with experiments. This approach underlines the fundamentally nonlinear process that takes place during ion exchange and is also valuable to properly model singlemode waveguide fabrication.

Paper Details

Date Published: 1 June 1996
PDF: 8 pages
Opt. Eng. 35(6) doi: 10.1117/1.600727
Published in: Optical Engineering Volume 35, Issue 6
Show Author Affiliations
Alexandru I. Lupascu, Univ. Politehnica Bucuresti (Romania)
Antoine P. Kevorkian, GEEO (France)
Thierry Boudet, GeeO (France)
Francoise Saint-Andre, GEEO (France)
Dominique Persegol, ENSERG (France)
Michel Levy, LIES-G (France)


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