Extended IWKB method for determination of the refractive=index profile in optical waveguides.

A simple method is outlined for the calculation of the refractive-index profiles of both multimode and monomode planar optical waveguides. The method is an extension of the well-established IWKB method. The parameters required are the dispersion relation of the surface index changes and the effective indices at different wavelengths. As an example, the refractive-index profile of a monomode z-cut KTiOPO(4) planar waveguide fabricated by Rb(+):K(+) exchange is computed. Close agreement is obtained, indicating the practicality of this method. The method is also applicable to optical waveguides in other materials, such as LiNbO(3), LiTaO(3), and glass.