Ab initio study of the nonlinear optical susceptibility of TeO2-based glasses

To gain a better insight into the origin of the outstanding nonlinear optic susceptibilities of TeO2-based glasses whose numerical characteristics are almost two orders of magnitude higher than those of SiO2-based glasses, a comparative computer simulation of their dielectric properties was performed using ab initio studies of a series of (SiO2)(p) and (TeO2)(p) polymer molecules. This comparison showed that these properties are reproducible only in a TeO2 glass simulated as an ensemble of chainlike (TeO2)(p) polymer molecules with p ->infinity, which was interpreted as evidence for the essential nonlocality of the electronic polarizability mechanism in that glass. The relevant model calculations showed the reasonableness of this hypothesis, which was subsequently used to explain the influence of modifier content on the nonlinear optic susceptibility of the tellurite glasses.