Optical spectroscopy of TeO2–GeO2 glasses activated with Er3+ and Tm3+ ions

The optical and spectroscopic properties of Er3+- and Tm3+-activated germano-tellurite glasses of molar composition 90TeO2:10GeO2 and 80GeO2:20TeO2, prepared by melt-quenching, have been studied. The refractive indices at three different wavelengths in the visible and near infrared have been measured. The vibrational properties of the glasses were studied by Raman spectroscopy. The Raman spectra indicate that the GeO2 and TeO2 components of the glasses do not mix well at the microscopic level. The spectroscopic properties of the rare earth ions were investigated by absorption spectroscopy and time resolved photoluminescence. The Er3+ 4I13/2 → 4I15/2 transition shows a bandwidth of about 70 nm with a lifetime of about 3 ms. The 3H4 → 3F4 transition of Tm3+ ion has a bandwidth of 115 nm in the TeO2-based glass, and of 135 nm in the GeO2-based glass. The lifetime of 3H4 is less than 0.2 ms.