Refractive index profiles of Y-branch 3-D optical waveguide in cross-section

In order to describe the refractive index profiles of Y-branch waveguide in x and y direction with only one expression,after analyzing the construction of glass substrate and the ion exchange process,an expression based on the product of refractive index distribution functions on the horizontal direction and the vertical direction was put forward by means of inverse variable separation method.Then the refractive index profiles were simulated with MATLAB.A 12 Y-branch optical waveguide was fabricated on BK7 glass substrate by means of Tl+-Na+ ion-exchange method,and its refractive-index profiles was measured by means of interference method.The simulated profiles were in good agreement with experimental results.The results show that the refractive-index distribution of Y-branch optical waveguide in cross-section can be reconstructed by the improved function n(x,y) easily.