The investigation of the composition dependence of the various properties of chalcogenide glasses has increased in recent years for two reasons. The ﬁrst one is scientiﬁc because this type of research provides new challenging fundamental problems for solid-state physicists. Second, many of these glasses have found applications in solid-state devices [1–3]. The Ge-In-Se system provides one member of these glasses and forms bulk glasses, by melt-quenching, over a wide range of compositions . This makes it a suitable model system for the investigation of the composition dependence of its properties.