Efficient lasing at 2.1 μm in a Ho:YAG laserpumped by a Tm:YLF laser

A laser based on a Ho:YAG crystal operating at a wavelength of ~2.1 μm under pumping by Tm:YLF laser radiation with a wavelength of 1.908 μm is studied. The laser operates in cw and repetitively pulsed regimes with a high beam quality (quality factor M²≤1.2). The cw radiation power reached 15 W with the total optical efficiency of ~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 μm.