Energy transfer processes and heat generation in Yb3+-doped phosphate glasses.

In this work we present a study of energy transfer processes in Yb3+-doped phosphate glasses with different OH- contents and Yb3+ concentrations. Fluorescence and thermal lens (TL) techniques were used in order to analyze the Yb3+–OH- and Yb3+-other impurity interactions. The role of OH- groups is also presented and discussed. The results show that in the low concentration region up to ∼3×1020 Yb ions/cm3, the interaction between Yb3+ and OH radicals is the dominant process reducing the lifetime, increasing the TL dioptric power, and then endangering the performance of the system. For the high Yb3+ concentration limit, the Yb3+-other impurity interaction, which is favored by energy migration, is comparable to the Yb3+–OH- energy transfer, even for high OH- concentration. The nonradiative decay rate due to hydroxyl groups follows Förster-Dexter theory [Ann. Phys. 2, 55 (1948); J. Chem. Phys. 21, 836 (1953)] except at low Yb3+ concentration, being more active at low OH- levels, where quenching rate is probably due to several impurities. [ABSTRACT FROM AUTHOR]