FABRICATION, SPECTROSCOPY AND LASER EMISSION OF Yb:Sc2O3 TRANSPARENT CERAMICS FROM CO-PRECIPITATED NANO-POWDERS

Yb(5%):Sc2O3 ceramic sample was fabricated by a co-precipitation and vacuum sintering method. In particular, we obtained ultra-fine and low agglomerated of 5at.% Yb:Sc2O3 powders with average particle sizes of 65.4 nm after (calcined (at 1100oC for 5h). The characteristics of the precursor and the calcined powders were analyzed by using BET, XRD, and SEM. By vacuum sintering (at 1825 °C for 10h) of the synthesized powders, which were used as starting materials, we obtained the ceramic sample with an in-line transmittance of 71.1% at 1100 nm and average grain sizes of 145 µm. Concerning the spectroscopic investigations we measured the absorption and emission cross section spectra of Yb3+ , its upper level lifetime, and we investigated the presence of other impurities. Quasi-CW laser oscillation was obtained at 1040.6 nm, in a longitudinally pumped cavity, using a fiber coupled diode laser emitting at 968 nm as a pump source. A maximum output power of 2.44 W was obtained, with a corresponding slope efficiency of 35% and an optical-to-optical efficiency of 25% with respect to the absorbed pump power [1]. The tunability of the ceramic was explored measuring a tuning range up to 55 nm (from 1001 nm to 1057 nm), broader than the value previously reported for Yb:Sc2O3 ceramics [?2, 3]. On the other hand the slope efficiency was slightly lower with respect to previous results, probably due to small scattering losses originated from internal residual pores.