Cooperative up-conversion in Eu3+,Yb3+-doped SiO2–PbO–PbF2–CdF2 oxyfluoride glass

Abstract

Novel oxy fluoride 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%.