Widely tunable, efficient 2 µm laser in monocrystalline Tm3+:SrF2

We report on the growth, spectroscopy, and laser operation of monocrystalline Tm3+:SrF2. Spectroscopic investigations confirmed the presence of broad absorption and emission bands caused by inequivalent doped sites, introduced by charge compensation e ects which also caused the clusterization of doping ions in the lattice. We obtained continuous-wave laser emission at about 2 µm, with e ciencies comparable with other Tm-doped crystals. We also achieved an uninterrupted tuning range of 180 nm between 1.8 and 2 µm. This characterization indicates that SrF2enhances the cooperative mechanisms between Tm ions, helping to obtain remarkable laser performances at low doping concentrations.