Numerical Method of Determining the Cutoff Frequency and Mode Speckle Pattern of Optical Waveguides

Abstract

Based on a numerical solution of the nonstationary wave equation, an algorithm for determining the eigenfunctions and eigenvalues of the LP im modes of axially symmetric optical waveguides is suggested. The cutoff frequency of the LP 11 mode of different waveguides is determined using the algorithm constructed. The results obtained are compared with the well-known analytical formulas and results of numerical calculations for the equivalent stepindex waveguide model. Based on the analytical results obtained, an eigenfunction and eigenvalue search algorithm is suggested for a waveguide with a two-dimensional refractive index profile (in particular, for an axially nonsymmetric waveguide).