Heterophase inclusions as a source of non-selective optical losses in high-purity chalcogenide and tellurite glasses for fiber optics

The results of investigation of the impurity and phase inclusions as sources of non-selective losses in high-purity chalcogenide and tellurite glasses are reported. Extinction on the SiO2 inclusions is shown to be responsible for non-selective losses in the chalcogenide glasses obtained by direct synthesis from elements in quartz equipment. Optimization of the temperature/duration conditions of the synthesis makes it possible to decrease these losses. The problem of achieving the theoretical minimum of optical loss in the glasses prone to crystallization is considered. The minimal scattering loss in such glasses can be limited not only by “freezing” fluctuations but also by the phase inhomogeneity of the glasses. A substantial contribution of the phase inclusions to optical losses is demonstrated on the example of high-purity tellurite glasses. The scattering in highly homogeneous samples of these glasses appears to be two orders of magnitude higher than the known theoretical value for scattering on “freezing” fluctuations.