Structures of Ge15Sb x Se85−x chalcogenide glasses affect their Raman gain performance

Abstract

A series of Ge15Sb x Se85−x (x = 5, 10, 15, 20, 25, and 30 mol%) chalcogenide glasses were prepared by traditional melt-quenching method. The refractive indexes, infrared transmissions, and spontaneous Raman spectra of the glass samples were measured. Based on the spontaneous Raman scattering theory and considering the measured Raman spectral data, we calculated the Raman gain coefficients of the chalcogenide glasses. The effect of Sb on the structures and Raman gain coefficients of the glass samples was then systematically investigated to understand the role of chemical composition in glass structure and Raman gain coefficient. In the Ge15Sb x Se85−x glasses, the number of heteropolar Ge–Se, Sb–Se bonds increased, whereas that of homopolar Se–Se bonds decreased at increased Sb concentration. The Raman gain coefficients increased until it reached a maximum value (290 × 10−13 m/W at Ge15Sb20Se65) and then decreased when the Sb concentration further increased. These results showed that the Raman gain coefficients of Ge–Sb–Se chalcogenide glasses without poisonous elements were over 300 times of that of commonly fused silica and closely correlated with the structures of the glasses, suggesting that the Raman gain coefficient can be adjusted by modifying the structures of the glasses. This work provides a new possibility for environment-friendly Raman fiber laser and amplifier materials.