High-power tunable laser operation of Ho:YScO 3 crystal at 2.1 µm

We report the Czochralski growth, spectroscopic characterization, and laser performance at 2.1 µm of a Ho:YScO 3 mixed sesquioxide crystal with a doping concentration of 0.4 at.%. Spectroscopic evaluation was performed based on room-temperature absorption and fluorescence measurements. Intensity parameters, radiative lifetime of the 5 I 7 manifold, and spontaneous emission rates were calculated based on Judd–Ofelt theory. For the 5 I 7 → 5 I 8 transition near 2.1 µm, the emission cross-section was derived to be 4.06 × 10 −21 cm 2 , with an exceptionally broad full width at half maximum spectrum of 210.14 nm. In the laser experiment, the laser delivers a maximum continuous-wave output power of 12.1 W with a slope efficiency of 31%. Wavelength tuning over 85 nm (2074–2159 nm) is demonstrated using a Lyot filter. These results establish Ho:YScO 3 crystal as a promising gain medium for high-power, broadly tunable, and potentially ultrafast 2.1 µm lasers.