Blue Upconversion Luminescence in Tm3+/Yb3+ Codoped CaWO4 Polycrystals
XU Yan-Ling1**, WANG Yun-Long1, SHI Lian-Sheng2**, TAN Xiang1
1Department of Chemistry, Harbin Institute of Technology, Harbin 150001 2Department of Material and Science Engineering, Harbin University of Science and Technology, Harbin 150080
Abstract：We investigate the upconversion emission of CaWO4:Tm3+/Yb3+ polycrystals prepared by the high-temperature solid-state method. The crystal structure of the polycrystals is characterized by means of x-ray diffraction. Under the excitation of a 980 nm continuous wave diode laser, the samples show intense blue upconversion emissions centered at 473 nm, corresponding to the 1G4→3H6 transition of Tm3+. The dependence of the upconversion emission intensity on the pump power of a laser diode is measured, and the results indicate that the two-photon and three-photon processes contribute simultaneously to the blue upconversion emissions. The possible multi-photon upconversion process and upconversion mechanisms are discussed.
2013, Vol. 30 
