High-Energy Q-Switched 1645-nm Er:YAG Laser With a Co2+:MgAl2O4 Saturable Absorber

We demonstrate a high-energy, passively Q-switched Er:YAG laser with a Co
²⁺
:MgAl
₂
O
₄
saturable absorber. Pumped by an Er-doped fiber laser, the Er:YAG laser generates 1645-nm pulses with the maximum pulse energy of 656 μJ and the pulse duration of less than 200 ns at a high repetition rate of 2.285 kHz. The output laser beam remains high beam quality with the maximum output power of 1.5 W. The horizontal and vertical M
²
factors are measured to be 1.22 and 1.32, respectively.