Compositional dependence of the optical properties of bismuth doped lead-aluminum-germanate glass

We report the compositional dependence of absorption, emission, decay constant and quantum efficiency (QE) of GeO2:Al2O3:PbO:Bi2O3 glass with the aim of finding the composition most suitable for a laser gain medium. As the Bi2O3 content was varied we observed a non-monotonic variation in absorption spectrum. The optimized composition was 87.4GeO2:6Al2O3:6PbO:0.6Bi2O3 (% molar) which had a QE of 67% but low transparency. We report the dependence of QE and decay constant on melting conditions of this glass. Adding 10% ZnO improved the transparency, therefore the optimized and transparent composition was 74.4GeO2:10ZnO:6Al2O3:6PbO:0.6Bi2O3, which had an emission full width at half maximum of 500 nm.