Thermal stability and optical transitions of Er3+/Yb3+-codoped barium gallogermanate glass

Er3+/Yb3+-codoped barium gallogermanate glass that is suitable for use in fiber lasers and optical waveguide devices has been fabricated and characterized. The differential scanning calorimetry, absorption spectra, infrared fluorescence and upconversion luminescence spectra of the glass have been measured. The spontaneous radiative transition probability, branching ratio, and radiative lifetime of the optical transitions have been calculated by using the Judd–ofelt theory. Differential scanning calorimetry result suggests that it is suitable to be a potential candidate for fiber drawing. Intense infrared fluorescence at 1531 nm and bright visible upconversion luminescence have been observed under 980 nm laser diode excitation at room temperature. The quadratic dependence of the upconversion emission on the excitation power indicates that two-photon steps are involved for the three visible emission bands. The possible upconversion mechanisms have also been discussed. All the results reveal that the Er3+/Yb3+-codoped barium gallogermanate glass fabricated in our work could be a suitable candidate for upconversion and infrared applications.