Pulse-pumped operation of divalent transition-metal lasers

The pulse-pumped operating characteristics of liquid-nitrogen-cooled Ni:MgF
2
, Co:MgF
2
, and Ni:CaY
2
Mg
2
Ge
3
O
12
(CAMGAR) solid-state lasers have been studied. The internal quantum efficiency of the Ni:MgF
2
laser was found to be limited to approximately 40 percent, presumably because of excited-state absorption. The Co:MgF
2
laser operated with near-unity quantum efficiency, and generated 150 mJ of diffraction-limited output at repetition rates up to 50 Hz. A continuous tuning range from 1.6 to 2.3 μm was observed along with
Q
-switched peak output powers of 80 kW. Laser operation from the garnet-structured crystal Ni:CAMGAR was obtained at a wavelength of 1.46 μm.