LAUSR

Abstract A series of Yb3+-doped yttrium aluminum monoclinic Y4Al2O9 (Yb:YAM) single crystals with different Yb3+ ion concentrations of 0.1, 1, 5 and 10 at.% have been grown by means of micro pulling down method. Low temperature absorption measurements revealed that Yb3+ incorporates at several well defined centers. Site selective excitation and emission experiments allowed to locate the energy levels of the ground 2F7/2 and 2F5/2 manifolds for the major centers detected in the system. The temperature dependence of the transition energies and linewidths of the resonant transitions was measured from 10 to 300 K and was well described by one phonon near resonant processes. The effect of Yb3+ concentration on the fluorescence spectra structure of Yb:YAM has been also investigated. It was observed that with the increasing of Yb3+ concentration luminescence from the low energy site dominates the emission spectrum. The fluorescence dynamics recorded at temperature range from 10 to 300 K under selective excitation of each site was analyzed.