Cooperative luminescence of Yb3+ ions in multisite YAM crystal
M. Kaczkan, M. Malinowski, A. Suchocki, S. Turczyński
Abstract
A series of Yb3+-doped yttrium aluminum monoclinic Y4Al2O9 (Yb:YAM) single crystals with Yb3+ ion concentrations of 0.1, 1, 5 and 10 at.% was grown by means of micro pulling down method. Blue emission was observed in Yb3+ activated YAM crystals under infrared site-selective laser excitation. Through the excitation and emission spectra, decay time measurements and excitation intensity dependence the process responsible for this anti-Stokes emission was assigned to the cooperative deexcitation of two Yb3+ ions. The results show that at 10% Yb3+ dopant concentration investigated system could be considered as single-site system in which cooperative luminescence is dominated by the energetically lowest Yb3+ site. Theoretical cooperative emission spectrum and the cooperative luminescence rate of Yb3+:YAM were calculated.