Improved method for recovering graded-index profile of isotropic waveguide by cubic spline function

Abstract

An improved method for recovering the refractive index profile of an isotropic graded-index waveguide is presented on the basis of the cubic spline interpolation method. The surface refractive index of the waveguide can be obtained by using a polynomial function that is related with the parameters of all modes. The simulation results of several typical index distributions show that this method can be employed to recover a graded-index profile well.