Optical spectroscopy and laser parameters of Zn2+/Er3+/Yb3+-tridoped LiNbO3 crystal

The Zn/Er/Yb:LiNbO3 and Er/Yb:LiNbO3 crystals were grown by the Czochralski technique. The laser characteristics of 1.54 mu m emission were predicted based on the Judd-Ofelt theory, and the intensity parameters Omega(t) (Omega(2)=7.23 x 10(-20) cm(2), Omega(4)=3.15 x 10(-20) cm(2) and Omega(6)=1.43 x 10(-20) cm(2)) were obtained. The stimulated emission cross sections (sigma(em)) at 1.54 mu m emission in Zn/Er/Yb:LiNbO3 were calculated based on the McCumber theory and the Fuchtbauer-Ladenburg theory. The gain cross section spectrum of Zn/Er/Yb:LiNbO3 crystal was also investigated. Under 980 nm excitation, a lenghthening lifetime of 1.54 mu m emission and an enhancement of green upconversion emission were observed for Zn/Er/Yb:LiNbO3 crystal. The studies on the power pump dependence and the upconversion mechanism suggested that both green and red upconversion emissions were populated via the three-photon process, and Zn2+ ion tridoping increases the probability of cross relaxation process between the two neighboring Er3+ ions. (C) 2012 Elsevier B.V. All rights reserved.