Among the excellent active media, thulium-doped yttrium oxide (Tm:Y2O3), belonging to the sesquioxide family of laser materials, stands out because it shows very high thermal conductivity, broad gain spectra and a relatively low maximum phonon energy, which makes it very suitable for two micron laser operation in several temporal regimes . However, its main limitation is the crystal growth methodology due to its high melting point making the growth of high quality crystals with large size to be a tedious and expensive task. This is confirmed by the fact that there are only few suppliers in the world. The transparent ceramic fabrication process solves these limitations and paves the way to spread the ceramic–based gain media in the future commercial solid-state laser systems . Besides the substitution of the crystalline gain media by the ceramic ones, cooling them to cryogenic temperatures suppresses thermal issues and enhances the material’s properties, such as thermal conductivity and transition cross-sections, being prerequisites for the development of high power lasers. To date, no deep studies on Tm:Y2O3 either in crystalline or ceramic form at cryogenic temperatures are found.
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