Preparation of Low-loss Ge15Ga10Te75 chalcogenide glass for far-IR optics applications

Ge15Ga10Te75 (GGT) glass shows good transparency between 2 and 25 μm wavelengths, good chemical and thermal stability to be drawn into fiber, which appears to be a good candidate for developing far-IR fiber-optics devices, although there are strong absorption peaks caused by impurities in the glass. With the aim of decreasing the content of impurities and micro-crystal particles in prepared GGT glass samples, a rapid heating furnace and the fast distillation method based on vapor evaporation plus deposition under vacuum condition was adopted. Properties measurements including Differential Scanning Calorimeter (DSC), Vis–NIR and IR transmitting spectra were performed on the prepared glass samples. Dependence of optical loss on the types of oxygenic getters and their contents and glass quenching temperature was also studied. All these results show that the average optical losses of distilled glass samples were greatly improved by the designated purification processes. Besides, the quality of the glass samples can be improved with the optimized quenching temperature. In all, the optical loss of the glass can be reduced effectively. Minimum optical losses of 0.042 dB/mm at 9 μm and 0.037 dB/mm at 12 μm are obtained after a right purification process, which are the lowest loss of the GGT chalcogenide glass nowadays.