Theoretical analysis of the mode structure in an optical fiber with axisymmetric refractive index profile

This paper presents a method to evaluate the modal structure of the optical fibers in visible and near-infrared wavelength range. Previously, we proposed the use these wavelength ranges for testing of short lines with optical time domain reflectometry technique. Here we focus on standard single-mode fibers which can be considered as weak coupling circular axisymmetric cross-section ones. Our approach to analysis is based on the representation of real optical fiber by an equivalent step profile or a combination of step profiles where each layer characterized by their local refractive index and radius. The numerical simulation was carried out for optical fibers ITU-T Rec. G.652 and G.657 fibers at wavelengths 650 nm and 850 nm. The electric field intensity distributions of lower-order guided modes and chromatic dispersion of fundamental mode are presented.