Ag-Na离子交换玻璃波导的折射率分布研究

用Ag-Na离子交换技术制备了玻璃平面波导.通过棱镜耦合技术测量了波导的模折射率,用反WKB方法拟合得到了平面波导的折射率分布为高斯分布.发现Ag-Na离子交换的扩散系数与交换时间有关,并且随着交换时间的增加而减小.使用随离子浓度变化的扩散系数求解扩散方程得到了玻璃内部Ag离子浓度分布,并通过SEM谱证实了求解的正确性；使用一次多项式模拟的方法求解折射率变化与Ag离子浓度变化之间的关系,得到了平面波导的折射率分布.与反WKB法只能获得多模离子交换平面波导的折射率分布相比,这种方法可以得到任意扩散时间下折射率变化与Ag离子浓度,可以获得单模平面波导的折射率分布.

Refractive Index Profiles of Ag-Na Ion-exchange Glass Waveguides

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.