Efficient 1.7 m pumping of 2 m thulium lasers

Solid-state 2 mu mlasers based on thulium-doped active media Tm:YAG, Tm:YAP, and Tm:YLF were investigated under 1.7 mu m resonant diode pumping. In contrast with standard 0.8 mu m pump wavelength, a high slope efficiency was achieved, up to 80% in the case of Tm:YAP and Tm:YLF, nearing a quantum limit without relying on Tm3+-Tm3+ cross-relaxation energy transfer. Low thermal load allowed for stable continuous-wave operation with good beam quality and output power up to 6 W (Tm:YAG, Tm:YLF), and 8W(Tm:YAP). (c) 2023 Optica Publishing Group https://doi.org/10.1364/OL.495369