The refractive index distribution of Tl+–Na+ ion-exchanged glass waveguide optical splitter in branch district

The buried waveguide optical splitter is fabricated by Tl+–Na+ ion-exchange technology on BK7 glass substrates, and the refractive index distribution in branch district is analyzed by the interference method technology. The shape of the same refractive index distribution of the six successive different points in branch district is changed little by little from a semicircle to a half ellipse gradually, and finally separates into two semicircles. We also compare the experiment data by the interference method with the mathematical solution by two-dimensional diffusion equation. And the refractive index distribution is the ‘improved’ Gauss function.