Intense red fluorescence from Ho/Yb codoped tellurite glasses

By optimizing the concentration ratio of Ho/Yb and using conventional melting and quenching methods, a group of Ho/Yb co-doped tellurite glasses with host composition of 78TeO(2)-12ZnO-10Na(2)O (mol.%, TZN) were made for red fiber laser development. Excited by 976 nm laser diode, intense green and red emissions were detected easily even by naked eyes. TZN glass codoped with 0.5 wt.% Ho2O3 and 3 wt.% Yb2O3 was found to present the strongest red emission with the intensity about three times higher than that of the green one, presenting a yellowish-orange color as observed. Besides direct energy transfer process from Yb to Ho as usual, it is believed that cooperative energy transfer upconversion from a pair of Yb donor ions to one Ho acceptor ion and excited state absorptions among different levels of Ho ion are commonly responsible for the observed intense red emission. 2012 Elsevier B.V. All rights reserved. (C) 2013 Elsevier B.V. All rights reserved.