High-energy, kHz-repetition-rate, ps cryogenic Yb:YAG chirped-pulse amplifier

We demonstrate amplification of picosecond laser pulses to 40 mJ at a 2 kHz pulse repetition frequency (PRF) from a two-stage cryogenic chirped-pulse Yb:YAG amplifier, composed of a regenerative amplifier (RGA) and a two-pass booster amplifier. The RGA produces 8.2 mJ of energy at 2 kHz PRF and 13.2 mJ at 1 kHz PRF with excellent energy stability (similar to 0.3% rms) and beam quality (M(2) < 1.1). Pulse stretching and compression are achieved by using a chirped fiber Bragg grating and a multilayer dielectric grating pair, respectively. Compressed 15 ps pulses from the RGA are obtained with a throughput efficiency of similar to 80% (similar to 6.5 mJ for 2 kHz). The booster amplifier further amplifies the pulses to 40 mJ at 2 kHz PRF, and similar to 32 mJ, similar to 15 ps pulses are expected after compression. The amplifier chain seeded from a femtosecond Yb-fiber laser enables the optical self-synchronization between signal and pump in optical parametric chirped-pulse amplifier applications. (C) 2010 Optical Society of America