Cryogenic Yb^3+-doped materials for pulsed solid-state laser applications [Invited]

We review recent progress in pulsed lasers using cryogenically-cooled Yb3+-doped gain media, with an emphasis on high average power. Recent measurements of thermo-optic properties for various host materials at both room and cryogenic temperature are presented, including thermal conductivity, coefficient of thermal expansion and refractive index. Host materials reviewed include Y2O3, Lu2O3, Sc2O3, YLF, YSO, GSAG and YVO4. We report on the performance of several cryogenic Yb lasers operating at 5-kHz pulse repetition frequency (PRF). A Q-switched Yb:YAG laser is shown to operate at 114-W average power, with 16-ns pulse duration. A chirped pulse amplifier achieves 115-W output using a Yb:YAG power amplifier. Output power of 73 W is obtained from a composite Yb:YAG/Yb:GSAG amplifier, with pulses that compress to 1.6 ps. Finally, a high-average-power femtosecond laser based on Yb:YLF is discussed, with results for a 10-W regenerative amplifier at 10-kHZ PRF.