Highly efficient in-band pumped Er:YAG laser with 60 W of output at 1645 nm

A high-power Er:YAG laser that is in-band pumped by a high-power cladding-pumped erbium-ytterbium codoped fiber laser operating at 1532 nm is reported. The Er:YAG laser produced 60.3 W of continuous-wave output at 1645.3 nm in a beam with M2 approximately equal to 3 for 82 W of incident pump power and 20 W of TEM00 output with M2 < 1.2 for 32.4 W of incident pump power. The slope efficiency with respect to incident pump power at pump powers of >20 W was approximately 81%. In the Q-switched mode of operation, a slightly modified resonator configuration incorporating an electro-optic Q switch produced pulses of approximately 4 mJ energy and approximately 100 ns (FWHM) duration, corresponding to a peak power of approximately 42 kW at a repetition rate of 1 kHz for an incident pump power of 16.8 W. The prospects for further improvement in continuous-wave and Q-switched performance are discussed.