Study Of Fabrication And Refractive Index Profiles Of The Ag-Na Ion-exchange Glass Planar Waveguides

In this paper, we mainly discuss the refractive index profiles of planar ion-exchange optical waveguides. We fabricated glass waveguides by sliver-sodium ion-exchange technique. The relation between the refractive index change and the ion concentration of silver is direct proportion; our work is finding the exact proportion by experiment. 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 silver-sodium 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 gets the refractive index profile of the waveguide. It is useful for the simulations of the waveguides witch are fabricated at the same experiment condition. Inverse WKB method only can be used for the refractive index profiles of multi-mode waveguide, wile this method can calculate the refractive index profiles and sliver internal ion concentration distribution at any time, so does the single-mode planar waveguide; It is very important for the design of single-mode silver-sodium ion exchange waveguide devices. The main conclusions of our work are: 1. The diffusion coefficient of silver ion isrelated to the silver ion concentration, and it can be expressed as: DA g= 0.017158×exp(290×( c x? c1)). It is confirmed by the experiment SEM. 2.The effective index comes from simulation of index change and concentration change is closed to that comes from Inverse WKB, and the error is 10-5. 3. The proportion of index change and ion concentration change is related to the diffusion time. With the time increase, the proportion decrease. 4. It can be seen from the simulation of single-mode waveguide, the surface index change of the single mode waveguide is 0.0248.