Phenomenon of the second uprising of Yb.Er:ZBLAN upconversion luminescence by the power of a 966-nm pumping laser

摘要

In the study of Rare-earth upconversion luminescence, it is always a key factor to efficiently increase the luminescence efficiency. Some exciting results have been achieved by the method of sensitization of codoped rare-earth ions. The high upconversion efficiency has been achieved by the very effective way of using the Yb$+3$PLU$/ ions' $+2$/F$-5/2$/ energy level as the intermediate level to transfer energy to many other rare-earth ions. Due to the strong absorption of Yb$+3$PLU$/ ions between the wavelength of 900 nm to 1000 nm, the population can be accumulated largely on the $+2$/F$-5/2$/ energy level and it becomes possible to transfer energy to higher levels. In recent years, the study of the upconversion luminescence of Ho$+3$PLU$/, Er$+3$PLU$/, Pr$+3$PLU$/ sensitized by Yb$+3$PLU$/ shows that Yb$+3$PLU$/ can cause quench at the same time with sensitization. So the codoped system of Yb$+3$PLU$/ $PLU R E (rare-earth ions) has very complex luminescence mechanism and in most situation the upconversion channels are not single or single direction. The study of the sensitization and quench is very important just because these complexities. Since the diode laser in 900 nm to approximately 1000 nm has developed quite well, it becomes possible to use mono-frequency diode laser to pump upconversion laser and fiber laser. In this paper, the upconversion luminescence of Yb(0.3)Er(0.3):ZBLAN glass induced by 966 nm diode laser was studied. Base on the experiment data, these results are calculated by the rate equation: when the cross energy transfer P between Yb$+3$PLU$/ and Er$+3$PLU$/ ions is quite weak, the upconversion luminescence become saturated gradually by the increase of the pump laser power; when the P is quite strong, it will cause a steep uprising of the luminescence before the saturation. This is the phenomenon of second uprising by the laser power that observed in the experiment.