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 (2H11/2, 4S3/2) → 4I15/2 emission in Er3+:Sc2O3 (at low Er content) under pulsed pumping into (4I15/2 → 4I9/2) absorption lines shows a competition between ESA (excited state absorption) (4I15/2 → 4I9/2) + (4I9/2 → 2H9/2) and ETU (energy transfer upconversion) (4I11/2 → 4I15/2) + (4I11/2 → 4F7/2) two-step processes, function on the excitation wavelength. The upconversion transfer rates were estimated. The features of the blue 1G4 → 3H6 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+1G4 emitting level is achieved by the energy transfer processes Nd(4F3/2 → 4I11/2) + Tm(3H4 → 1G4), or the chain Nd(4F3/2 → 4I9/2) + Yb(2F7/2 → 2F5/2) followed by the Yb(2F5/2 → 2F7/2) + Tm(3H4 → 1G4), function on Yb3+ content.