QUANTUM EFFICIENCY OF PR3-CERAMICS( DOPED TRANSPARENT GLASS)

The quantum efficiency of the 1.3 mu m transition in Pr3+ doped oxyflu oride transparent glass ceramics is measured using a self-calibrating fluorescence ratio technique. The measured value of 8%+/-1% is much hi gher than expected for Pr3+ in an oxide glass, and is consistent with the incorporation of the Pr3+ ions into the fluoride nanocrystals of t he glass ceramic. Measured quantum efficiencies are compared with valu es calculated using the Judd-Ofelt theory, and it is found that the be st agreement is obtained when fractional differences between calculate d and measured oscillator strengths are minimized, rather than absolut e differences. The Judd-Ofelt analysis is used along with a spectral a nalysis to show that excited-state absorption should not significantly reduce the gain around 1.3 mu m in these materials. The fluorescence ratio technique used to measure the quantum efficiency also provides i nformation about ion-ion interactions at higher concentrations. It is found that the addition of the monovalent dopant Ag+ reduces the tende ncy of the Pr3+ ions to cluster, allowing higher concentrations of Pr3 + without significant concentration quenching. (C) 1998 American Insti tute of Physics. [S0021-8979(98)05703-X].