Under the excitation of 980 nm diode laser, intense green emission （5F4＋5S2–5I8） of Ho3＋ was observed in Ho3＋ and Yb3＋ co-doped cubic Y2O3. The doping concentration and laser power dependence of the upconverted emission were studied. The decay curves of 5F4＋5S2 emission of Ho3＋ under the excitation of 355 nm pulse laser were measured to investigate the energy transfer process between Ho3＋ and Yb3＋. The results indicated that two-photon process was responsible for the upconversion （UC） emission. The Ho3＋ concentration of 0.04 mol.% and the Yb3＋ concentration of 5 mol.% were determined to be the best value for the strongest Ho3＋ emission under the excitation of 980 nm light. The cross-relaxation between two neighboring Ho3＋ ions and the back energy transfer from Ho3＋ to Yb3＋ were important factors for determin- ing the optimal doping concentration. This material was a promising candidate for the application in biomedical fluorescent labels for the intense green emission upon excitation of near-infrared （NIR） light.
