Blue upconversion of cubic Gd2O3:Er produced by green laser

Erbium-doped cubic Gd2O3 particles were prepared by a simple sol-gel method. The upconversion luminescence spectra of Er3+ were investigated under excitation into the H-2(11/2) level by 514.5 nm Ar+ laser. The dependence of upconverted emissions on laser power, Er3+ ions concentration, and temperature were carried out to understand the blue upconversion mechanisms, and the results show that the excited state absorption (ESA) from S-4(3/2) to D-4(5/2) level and energy transfer (ET) process S-4(3/2) --> S-4(3/2) --> I-4(15/2) --> (4)G(9/2) are responsible for the phenomenon. (C) 2004 Elsevier B.V. All rights reserved.