Numerical method for the reconstruction of the refractive index profile of diffused waveguides

A description is given of a method for reconstructing the refractive index profile of diffused waveguides on the basis of inversion of the WKB formula. It is shown that this method can be used to reconstruct equally accurately both parabolic and exponential profiles. Additional data (the mode spectrum determined at several wavelengths and the effects of different coatings on a waveguide) make it possible to find the profiles of few-mode waveguides. Determination of the effective refractive indices of the TE and TM modes for two directions of propagation in the plane of an anisotropic waveguide gives the necessary data for the reconstruction of the profile of all the components of the permittivity tensor.