Thermal and optical properties of Er3+-doped oxyfluorotellurite glasses

Er3+-doped oxyfluorotellurite glasses with four different concentrations of Er3+ ions have been prepared and investigated their thermal, optical absorption, excitation and luminescence properties. From the DSC spectra, glass transition and onset of crystallization temperatures have been found. Judd-Ofelt intensity parameters have been derived from the absorption spectrum and are in turn used to calculate radiative properties for the important luminescent levels of Er3+ ions. The calculated radiative properties are comparable to experimental values. The glasses show intense green and weak red emission under normal excitation with 451 nm. The decrease in emission intensities and lifetimes of the 4S3/2 level with concentration of Er3+ ions has been explained as due to energy transfer processes between Er3+ ions. The stimulated emission cross-sections and quantum efficiencies of the green and infrared emissions have been determined. The results indicate that the glasses may be suitable for use as a laser medium in making solid-state green laser by normal pumping route and as laser medium and optical amplifier in the 1.5 μm region.