Preparation of high purity glasses in the Ga–Ge–As–Se system

• The high-purity Ge16As17Se64Ga3 glasses were prepared.
• The transport reaction route of metallic Ga transfer in a GaI3 vapor flow was used.
• Glass samples are characterized by low impurity content.

Small additions of Ga to Ge–As–Se glasses are known to enhance rare earth ion solubility in Ge–As–Se chalcogenide glasses designed for active optical applications. The effect of variants and conditions for producing samples of an exemplar Ge16As17Se64Ga3 (atomic%) glass on optical transmission, and the content of limiting impurities, is investigated. To prepare the high-purity glass samples, chemical distillation for purification of the Ge–As–Se base-glass is used. Next, a new vapor phase transport approach of metallic Ga transfer in a GaI3 flow is developed to purify and add the batch of metallic gallium into the silica-glass reactor for the Ge–As–Se–Ga glass synthesis. A thermodynamic equilibrium based vapor phase transport model is discussed. In the best examples of these glasses, the content of residual impurities is: hydrogen – 0.15 ppm, oxygen – <1 ppm, and transition metals – less than 0.1 ppm.