The chromatic dispersion of optical guiding structures by an approximation of numerical results

The guiding structures in photonic and integrated optical circuits have complex geometries and refractive‐index profiles so that numerical methods must be used to analyze them. When it is necessary to evaluate parameters such as group delay or dispersion coefficient, which involve first and second derivatives of the numerically calculated propagation constants of the modes, the required accuracy is not easy to obtain. Suitable functions may be used to fit, in a least‐squares sense, the numerical solutions and to easily obtain derivatives from a direct analytical calculation. © 1994 John Wiley & Sons, Inc.