High power Tm:YLF bulk laser wavelength-stabilized by two F-P etalons

In this work, we report a 1908 nm Tm:YLF bulk laser pumped by the fiber coupled diode laser, the maximum output power of which was 70.8 W at the incident pump power of 184.6 W, corresponding to the optical-to-optical efficiency of 38.4% and slope efficiency of 43.7%. The laser wavelength was selected and restricted at 1908.1 nm by two etalons inserted in the cavity. The laser beam quality factors M² were measured to be 1.79, 1.85 and 1.90 at the output power of 20.1 W, 41.2 W and 65 W, respectively. A laser wavelength shift of only 0.1 nm with the incident pump power varying from 20.1 W to 184.6 W was observed.