title: [Luminescence properties and up-conversion mechanism of Er3+ -Yb3+ -Tm3+ co-doped CdF2: PbF2-based glass].
abstract: Under 980 nm excitation, we obtained five intense up-conversion luminescence bands in Er3+ -Yb3+ -Tm3+ co-doped CdF2: PbF2-based glass as follows: infrared (800 nm), red (645 nm), green (545 nm and 525 nm), blue (480 nm ) and violet (407 nm) up-conversion luminescence. With the addition of Tm3+ , the intensity of 480 nm blue luminescence increased notably compared with that of co-doped Yb3+ -Er3+ sample, which attributed to Tm3+ special energy level structure; logI-logP plot of the luminescence intensity versus pump power shows that 480 nm luminescence emission is a two-photon excitation process induced by the cooperative up-conversion between two Yb3+ ions and the slope of logI-logP plot decreases gradually with increasing pump power and shows a tendency to bend down. The up-conversion mechanism is analyzed in detail under 980 nm semiconductor laser excitation; the dependence of 480 nm up-conversion luminescence intensity on the pump power under the steady states is discussed by using rate equation and the results agree well with the experiments.
authors.affiliation: Faculty of Material and Photo-electronic Physics, Xiangtan University, Xiangtan 411105, China.
authors.forename: Li-wen
authors.initials: LW
authors.lastname: Yang
authors.forename: Zheng-wei
authors.initials: ZW
authors.lastname: Liu
authors.forename: Si-guo
authors.initials: SG
authors.lastname: Xiao