A Stable Diffusion-Bonded Tm:YLF Bulk Laser with High Power Output at a Wavelength of 1889.5 nm

A high power diode-pumped diffusion-bonded Tm:YLF laser operating at 1889.5 nm with a FWHM linewidth of less than 0.1 nm is reported. A Brewster plate and two Fabry–Perot etalons are inserted in the laser cavity for spectral narrowing and stabilization. Under an incident pump power of 136.8 W, 46.1 W of output power is achieved, corresponding to an optical-to-optical conversion efficiency of 33.7% and a slope efficiency of 42.8%. The laser wavelength shift of only 0.07 nm with the incident pump power from 20.1 W to 136.8 W is observed. The M² factor at maximum output power is calculated to be 2.3 in the x-axis and 2.0 in the y-axis, respectively.