Rare-Earth-Doped Sesquioxides for Diode-Pumped High-Power Lasers in the 1-, 2-, and 3-μm Spectral Range

Sesquioxides combine excellent thermomechanical properties, comparably low phonon energies and a strong crystal field, making them ideally suited for broad band emitting high power laser materials in the infrared and mid-infrared spectral range. In this paper, the latest progress on diode pumped highly efficient high-power solid-state lasers based on rare-earth doped sesquioxides, Lu₂O₃, Sc₂O₃, and Y₂O₃, as well as different mixed sesquioxides (Lu_aSc_bY_c)₂O₃ with a + b + c = 1 is reviewed. While Yb³⁺ -doped sesquioxides allow for record high efficiencies at several 100 W of output power in continuous wave operation and record high average powers in pulsed mode in the 1-μm spectral range, Tm³⁺- and Ho ³⁺-doped sesquioxides enable efficient broad band laser operation and ultrashort pulse duration around 2 μm. Finally, Er³⁺-doped sesquioxides enabled the highest efficiencies and output powers demonstrated so far at room temperature in the mid-infrared range at 3 μm.