Siberian Federal University

In this study, thulium and holmium codoped yttrium sesquioxide (Tm,Ho:Y2O3) transparent ceramics were fabricated using solid-state vacuum sintering of nano-sized particles with complex chemical composition synthesized by the laser ablation method. The as-produced powder was in the form of soft aggregates composing of individual spherical particles with a diameter of 16 nm, whose crystal structure underwent conversion from the monoclinic (space group C2/m) to the cubic (space group Ia-3) modification after consolidation into ceramic material. The morphological properties along with their correlation to the optical quality of Tm,Ho:Y2O3 ceramics vacuum sintered at 1700–1775 ◦C were investigated. The sample sintered at 1750 ◦C featured higher transmittances (81.6% at λ = 600 nm and 83.0% at λ = 1000 nm) and lower content of scattering centers of 0.00014 vol.%. The absorption cross-section at 797 nm due to the 3H6→3H4 transition of Tm3+ ions was 4.44×1021 cm2. The broad luminescence band was observed from 1750 nm to 2100 nm owing to the combination of cross-relaxation of Tm3+ ions and nonradiative energy transfer from the 3F4 level (Tm3+) to the 5I7 level (Ho3+). These results suggest that Tm,Ho-codoped Y2O3 transparent ceramics are promising gain media for broadly tunable and mode-locked lasers emitting in the 2-μm spectral range