Determination of two-dimensional optical waveguide index distribution function parameters from effective indexes

The method described is based on the least-squares method and gives the maximum-likelihood estimate of the parameters. Its practicality is demonstrated by application to waveguides with three types of refractive index distribution. First, the convergence of the method is shown by computer simulations of a waveguide with an exponential refractive index distribution. Second, a Ti-diffused LiNbO ₃ waveguide is considered as an example of a Gaussian refractive index distribution. The computed refractive index distribution agrees with computational results obtained by S. Fouchet et al. (1987). Third, a proton-exchanged LiNbO₃ waveguide is considered as an example of a step refractive index distribution. The computed depth of the waveguide agrees with the measured depth