Cooperative up-conversion in Eu3Â +,Yb3Â +-doped SiO2-PbO-PbF2-CdF2 oxyfluoride glass

Novel oxyfluoride glass doped with YbF3 and Eu2O3 is synthesized in the SiO2-PbO-PbF2-CdF2 system by melt-quenching technique. Its physical properties, as well as the optical absorption of Eu3 + and Yb3 + ions are studied. Spectroscopic properties of Eu3 + ions are modeled within modified Judd-Ofelt theory, yielding absorption oscillator strength, luminescence branching ratios and radiative lifetime of 5D0 state. Intrinsic emission of Eu3 + ions under direct excitation in the UV, as well as up-conversion luminescence under near-IR excitation via cooperative energy transfer, 2Yb3 + → Eu3 +, are studied. In the latter case, the glass provides intense reddish-orange emission with CIE coordinates x = 0.636, y = 0.363. The asymmetry parameter R for Eu3 + emission in the studied glass is about 8. The efficiency of this transfer mechanism is estimated from shortening of 2F5/2(Yb3 +) lifetime to be 10 ± 1%.