Power Scaling and Thermal Lensing in ~2.8 μm Er:CaF2 Lasers: Effect of the Pump Wavelength

Er:CaF 2 laser generated 0.83 W at 2800 nm with a slope efficiency of 31.6% and a threshold of 24 mW. Thermal lensing and heat loading are compared under pumping into the 4 I 11/2 and 4 I 9/2 states.