Upconversion emission of RE3+ in Sc2O3 ceramic under 800 nm pumping

The infrared (800 nm range) radiation conversion to visible in Er3+ doped or (Nd, Yb, Tm) co-doped Sc2O3 transparent ceramics was investigated. The green upconversion (H-2(11/2) -> S-4(3/2)) -> I-4(15/2) emission in Er - 3 (at low Er content) under pulsed pumping into (I-4(15/2) -> I-4(19/2)) absorption lines shows a competition between ESA (excited state absorption) (I-4(15/2) -> I-4(19/2)) + (I-4(19/2) -> H-2(9/2)) and ETU (energy transfer upconversion) (I-4(11/2) -> I-4(15/2)) +(I-4(11/2) -> F-4(7/2)) two-step processes, function on the excitation wavelength. The upconversion transfer rates were estimated. The features of the blue (1)G(4) -> H-3(6) Tm3+ upconversion emission in (Tm, Nd, Yb):Sc2O3 ceramic, under pumping at 808.3 nm were also analyzed. At this wavelength both Nd3+ and Tm3+ present ground state absorption. The data suggest that the population of Tm3+ (1)G(4) emitting level is achieved by the energy transfer processes Nd(F-4(3/2) -> I-4(11/2)) + Tm(H-3(4) -> (1)G(4)), or the chain Nd(F-4(3/2) -> I-4(19/2)) + Yb(F-2(1/2) -> F-2(5/2)) followed by the Yb(F-2(5/2) -> F-2(7/2)) + Tm(H-3(4) -> (1)G(4)), function on Yb3+ content. (C) 2008 Elsevier B.V. All rights reserved.