Spectroscopy and energy transfer in lead borate glasses doubly doped with Tm and Dy ions.

Lead borate glasses singly and doubly doped with Tm and Dy were prepared by traditional melt-quenching technique. The emission spectra of rare earths in studied glass systems were registered under different excitation wavelengths. The observed emission bands are located in the visible spectral region. They correspond to D→F (blue) and G→H (blue) transitions of Tm as well as F→H (blue), F→H (yellow) and F→H (red) transitions of Dy. Moreover, the energy transfer process from Tm to Dy was observed. The luminescence bands originating to characteristic transitions of thulium and dysprosium ions are present on emission spectra under direct excitation of Tm. Luminescence lifetimes for the excited states of Tm and Dy ions in lead borate glass were also determined based on decay measurements. The luminescence intensities and lifetimes depend significantly on the relative concentrations of the optically active dopants.