Material and Mode Dispersion in GeO ₂ ·B ₂ O ₃ ·SiC ₂ Glasses

Abstract

Material and mode dispersion in fibers made from glasses in the system GeO 2 ‐B 2 O, 3 ‐SiO 2 have been calculated using refractive index dispersion results for these glasses. Refractive indices were measured on bulk glass specimens using the minimum deviation method at wavelengths from 0.4358 to 1.0830 μm. The resultant data were then fitted to a 3‐term Sellmeier dispersion relation for each glass composition. The fitted equations and a recent theory on the relation of the optimum index profile in a graded index optical waveguide to pulse dispersion were used to calculate the exponent α, which characterizes the shape of the profile, for several practical fiber models. The most effective profile shape for reducing pulse dispersion is a function of wavelength, composition, and fictive temperature. The present data were used elsewhere to predict accurately the optimum profile for minimization of pulse dispersion in several fiber systems consisting of germanium borosilicate glasses.