DETERMINATION OF THE TRUNCATION ORDER AND NUMERICAL WINDOW FOR MODELING GENERAL DIELECTRIC WAVE-GUIDES BY THE FOURIER METHOD

The Fourier method of Henry and Verbeek [4], provides fast and accurat e computation of the guided modes of 2- and 3-D waveguides with either homogeneous or inhomogeneous refractive index profiles, However, the accuracy and speed of the computation depends on the size of the numer ical window and the number of terms (or truncation order) in the Fouri er expansion of the solution to the reduced scalar wave equation. in t his paper, we present a novel technique for the a priori determination of the numerical window and truncation order (of the Fourier method) by using the Wentzel-Kramers-Brillouin technique and the effective ind ex method. This obviates the need to iteratively correct the computati onal parameters when using the Fourier method.