High-energy kHz Yb:KYW dual-crystal regenerative amplifier

A highly stable Yb:KYW based dual crystal regenerative amplifier is demonstrated, which generates at 1 kHz 6.5-mJ pulses before and up to 4.7-mJ sub-ps pulses after compression with multilayer-dielectric gratings, respectively. The stretcher is compact and based on chirped-fiber Bragg gratings. In continuous-wave operation, 20 W are extracted with a slope efficiency of 40%. The experimental data are in agreement with detailed simulations of the laser dynamics.