Holmium ions (Ho3+) are interesting because of their emission in the eye-safe spectral range slightly above 2 µm due to the 5I7 → 5I8 transition. Tm3+,Ho3+-codoping is frequently used for excitation of Ho3+ ions: Tm3+ ions (donors) efficiently absorb pump radiation at ~0.8 µm and non-radiatively transfer their energy to Ho3+ ions (acceptors), 3F4 (Tm3+) → 5I7(Ho3+). The codoping scheme also benefits from the combined gain bandwidths of both active ions which is attractive for broadband wavelength tuning and ultrashort pulse generation [1]. Cubic sesquioxides A2O3 (where A = Y, Lu, Sc or their mixture) are the well-known host matrices for rare-earth doping. They can be elaborated in the form of transparent polycrystalline ceramics [2]. In the present work, we report on the first Tm,Ho:A2O3 ceramic laser. The ceramic was prepared via solid-state vacuum sintering at 1750 °C for 5 h using nanoparticles synthesized by co-evaporation of a solid target by a 1070 nm Yb-fiber laser followed by sedimentation. ZrO2 (5 mol%) was used as a sintering additive. The actual composition of nanoparticles was (Tm0.031Ho0.006Y0.848Sc0.115)2O3. The sintered ceramic was annealed in air at 1400 °C for 2 h. An XRD study revealed a single phase substitutional solid solution (bixbyitetype structure, sp. gr. Ia(equation presented), a = 10.510 Å). The ceramic featured a uniform and dense internal structure composed of tightly packed grains (average size: 20.7 μm), see Fig. 1(a). Under excitation at 774 nm, the ceramic exhibited intense emission around 2 µm due to the spectrally overlapping 3F4 → 3H6 Tm3+ and 5I7 → 5I8 Ho3+ transitions, Fig. 1(b). A study of luminescence dynamics from the 3F4 Tm3+ and 5I7 Ho3+ manifolds confirmed an efficient and unidirectional Tm3+ → Ho3+ energy transfer with an equilibrium lifetime of 5.3±0.5 ms, Fig. 1(c). © 2023 IEEE.