High power Ho:Y₂O₃ ceramic laser with controllable output intensity profile at 2.1 µm

We report on a high-power Ho:Y₂O₃ ceramic laser at 2.1 µm with controllable output beam profile ranging from LG₀₁ donut, flat-top to TEM₀₀ mode using a simple two-mirror resonator. In-band pumped at 1943nm using a Tm fiber laser beam shaped via a coupling optics comprising a capillary fiber and lens-combination to achieve distributed pump absorption in Ho:Y₂O₃ and hence selective excitation of the target mode, the laser yields 29.7 W of LG₀₁ donut, 28.0 W of crater-like, 27.7 W of flat-top and 33.5 W of TEM₀₀ mode output for absorbed pump power of 53.5 W, 56.2 W, 57.3 W and 58.2 W, respectively, corresponding to a slope efficiency of 58.5%, 54.3%, 53.8% and 61.2%. This is, to the best of our knowledge, the first demonstration of laser generation with continuously tunable output intensity profile at ∼2 µm wavelength region.