In-band pumped Ho3+:KY3F10 2 micron laser

We report the first observation to our knowledge of room-temperature continuous-wave laser operation on the I-5(7) -> I-5(8) transition of Ho3+ ions in a KY3F10 single crystal. Using a Tm-doped silica fiber laser operating at 1938 nm as a pump source, a maximum laser power of 1.8 W was obtained at a wavelength of similar to 2040 nm for 27 W of absorbed pump power with a slope efficiency of 19.1% with respect to absorbed power. At low cavity output coupling, the lasing wavelength shifted to 2060.5 nm. The beam propagation factor (M-2) was measured to be <1.06 at the maximum output power, confirming fundamental transverse-mode (TEM00) operation. Performing a Caird analysis, we determined resonator round-trip losses and intrinsic slope efficiency of 30% and 43.8%, respectively.