Efficient lasing at 2.1 mu m in a Ho : YAG laser pumped by a Tm : YLF laser

A laser based on a Ho:YAG crystal operating at a wavelength of similar to 2.1 nm under pumping by Tm : YLF laser radiation with a wavelength of 1.908 mu m is studied. The laser operates in cw and repetitively pulsed regimes with a high beam quality (quality factor M(2) <= 1.2). The cw radiation power reached 15 W with the total optical efficiency of similar to 55 %. In the active Q-switched regime (achieved using an acousto-optic Q-switch), a highly stable repetitively pulsed lasing was obtained with a pulse repetition rate of 2.5-10 kHz, a pulse duration of 25-55 ns, and an average power up to 14.7 W. Using intracavity frequency selection, lasing was obtained at individual spectral lines in three wavelength regions, near 2.09, 2.097, and 2.123 mu m.