Refractive Index Profiles of Ag-Na Ion-exchange Glass Waveguides
Ag-Na离子交换玻璃波导的折射率分布研究

Glass planar waveguides were prepared by Ag-Na ion-exchange technique.The effective refractive indexes were measured by the prism coupling.Inverse WKB method has been used to fit refractive index profiles of the waveguides,the best fitted refractive index profiles is Gaussian distribution.The diffusion coefficient of Ag-Na ion exchange and the exchange time are related.With the time increase,the diffusion coefficient decrease.The diffusion equation was solved using the diffusion coefficient which changes with silver internal ion concentration distribution.The correctness of the solution was confirmed by SEM.Using a polynomial method for the simulation of the relationship between the refractive index change and the concentration of silver ions,and finally get the refractive index profile of the waveguide.Inverse WKB method only can be used for the refractive index profiles of multi-mode waveguide,but this method can calculate the refractive index profiles and sliver internal ion concentration distribution at any time,so does the single-mode planar waveguide.