Spectroscopic properties of Pr3+ions in lead germanate glass

Abstract
The visible luminescence of Pr3+-doped lead germanate glass of composition (in mol%) 60PbO-40GeO2 has been investigated for two Pr3+ concentrations at different temperatures by using steady-state and time-resolved laser spectroscopy. Concentration quenching of the 1D2 emission is observed for Pr3+ concentrations higher than x = 0.05 mol% even at 4.2 K and attributed to a cross relaxation process. Anti-Stokes emission from the 3P0 level following excitation of the 1D2 state has been observed for the sample doped with 0.5 mol% of Pr3+. The temporal behaviour of the anti-Stokes emission from the 3P0 level following excitation of the 1D2 state suggests that energy transfer is responsible for the upconversion process.