High-power and efficient operation of Ho:Lu2O3 ceramic laser at 2.1  <b> <i>μ</i> </b> m spectral gain region

We report on the power scaling and high-efficiency operation of a Ho:Lu2O3 ceramic laser at 2.1 μm in-band pumped by a high-power, narrow-linewidth Tm-doped fiber laser at 1942 nm. The 0.5 at. % Ho3+-doped Ho:Lu2O3 ceramic was fabricated in-house through a vacuum sintering plus hot isostatic pressing (HIPing) process, showing a relatively low scattering loss of &amp;lt;2.1% cm−1. A record output power of 10.2 W at 2121 nm was achieved with 45 W of absorbed pump power, corresponding to a slope efficiency of 27.5%. The beam quality factors (M2) at the maximum output were measured to be 1.34 and 1.28 in the x- and y-directions, respectively. The laser power and efficiency were enhanced by two orders of magnitude and nearly 30-fold compared to the previous results, which confirms the significant power scaling potential of in-band pumped Ho:Lu2O3 ceramic lasers for hundred-watt-level operation upon improved quality of the ceramic with a more homogeneous and denser microstructure.