Detailed study of silver metallic film diffusion in a soda-lime glass substrate for optical waveguide fabrication

We present the study of multimode glass waveguides fabricated by a silver-ion electromigration process followed by a diffusion process. The study is concerned mainly with the diffusion process, which occurs by variation of the diffusion time. The obtained guides are analyzed by the prism-coupling technique, which determines their effective refractive indices that are treated by the inverse WKB method,assumed to be proportional to the silver ions' concentration profiles, for which a Gaussian model is attributed. Diffusion coefficients then are determined from these Gaussian profiles experimentally by both methods. These diffusion coefficients show a concentration dependence related to the variation of the diffusion time. A mathematical model representing the best fit to this dependence is also presented. Finally, our results are compared with other research results, with which we find good agreement.