In this paper, we present the acousto-optical (AO) Q-switched performance of a holmium (Ho):gadolinium tantalate (GdTaO₄) (Ho:GTO) laser pumped by a thulium (Tm)-fiber laser emitting at 1.94 µm. In the efficient continuous wave (CW) regime, a maximum output power of 30.5 W at 2068.8 nm was achieved, corresponding to a slope efficiency of 74.9% with respect to the absorbed pump power. In the Q-switching regime, pulse energies of 2.4 mJ, 1.2 mJ, and 0.9 mJ were obtained with pulse repetition frequencies of 10 kHz, 20 kHz, and 30 kHz, respectively. The minimum pulse widths were 18 ns, 23 ns, and 26 ns, corresponding to peak powers of approximately 133.3 kW, 52.2 kW, and 34.6 kW, respectively.

A high-energy, alignment-insensitive, injection-seeded Q-switched Ho:yttrium aluminum garnet (YAG) single-frequency laser is developed. Both the slave Q-switched laser and the seed laser are Ho:YAG ring lasers based on a pair of corner cubic reflectors. The seed laser has an available power of 830 mW at 2096.667 nm. At 100 Hz, the Q-switched Ho:YAG laser provides a single-frequency pulsed output using injection-seeded technology. The 7.3 mJ single-frequency pulse energy from the slave laser has a pulse width of 161.2 ns and is scaled to 33.3 mJ after passing through the Ho:YAG single-pass amplifier. According to the measurement results of the heterodyne beating technique, the single-frequency pulse has a half-width of 4.12 MHz.

We demonstrate a high power, Er:LuAG single-longitudinal-mode laser in an anti-misaligned resonator. Based on the Faraday effect, a 1.61 W single-longitudinal-mode (SLM) laser is obtained with the double corner-cube-retroreflector (CCR) structure, and the tunable wavelength is 1649.2–1650.3 nm. Additionally, we investigate the anti-misalignment characteristics when the CCR moves and rotates along the optical axis. Furthermore, by utilizing the Er:LuAG amplifier, the maximum 2.32 W single-longitudinal-mode laser at 1649.6 nm is achieved. The beam quality factors M² of the 2.32 W Er:LuAG single-longitudinal-mode laser are 1.23 and 1.25 along the horizontal (x) and vertical (y) directions, respectively.

A single-frequency, Q-switched Er:YAG laser, pumped by a 1532 nm fiber laser, has been demonstrated. At the pulse repetition frequency (PRF) of 200 Hz, the maximum single-frequency laser of 5.5 mJ is attained, and, correspondingly, the pulse width is 212 ns. Using the heterodyne technique, the single-frequency laser spectrum’s full width at half maximum is determined to be 2.73 MHz. The experimental results show that the single-frequency laser has excellent beam quality factors (M²) of 1.18 and 1.21.