Upconversion luminescence of ZBLAN:Tm3+Yb3+ glass pumped by a ~970-nm LD and its concentration effect

摘要

Wide wavelength range of upconversion fluorescence at 360 nm, 450 nm, 475 nm, 647 nm, and 800 nm were observed in Tm$+3$PLU$/ and Yb$+3$PLU$/ codoped ZBLAN glass when pumped by a laser diode at approximately 970 nm. Those emissions are from three metastable states $+1$/D$-2$/, $+1$/G$-4$/ and $+3$/F$-4$/, respectively. Three samples with varying Tm$+3$PLU$/ and Yb$+3$PLU$/ ion doping were investigated. It was shown that the luminescence intensity, as well as the dependence of intensity on laser power density, vary strongly with rare earth ion concentrations. And the mechanism for the population of $+1$/D$-2$/ level is clarified further.