In this report

the refractive index-profile of semiconductor-doped glass waveguide has been determined based on the measurement of effective refractive indices of the multi-mode waveguide. Firstly

a reiterative method is used to determine the surface refractive index of waveguide with the effective refractive index measured. And then the different order mode depth and the effective refractive-indices of waveguide are evaluated by computer with the Fermi refractive index-profile mode equation. When laser power density coupled into the waveguide is changed

the nonlinear refractive index coefficient of the waveguide can be measured in different mode depth. So the nonlinear refractive index coefficient versus power densities is obtained and the nonlinear saturation value is 1.54×10

-4

.