High-energy diode-pumped Yb:YAG chirped pulse amplifier

A diode-pumped chirped-pulse amplifier (CPA) system based on Yb:glass and Yb:YAG as a picosecond pump source for a future ultra-high peak-power optical parametric chirped-pulse amplifier (OPCPA) is currently under development. Pulses as short as 300 fs generated in an Yb:glass mode-locked oscillator have been stretched to the nanosecond level. The seed pulses are then amplified up to an output pulse energy of 100 mJ in a diode-pumped Yb:glass regenerative amplifier and a subsequent Yb:YAG booster. At a small-signal gain of 10(3) in Yb:YAG the initial pulse bandwidth of 4 nm (FWHM) has been gain-narrowed to 1.5 nm, which allows the re-compression to 1.1 ps. With a multi-pass Yb:YAG amplifier which has been seeded by a Q-switched sub-10-nanosecond laser an output pulse energy of 2.93 has been achieved. In quasi-cw-mode a peak output power of 7.6kW and a timing range of 5nm have been obtained. The foot-print-size of the multi-pass amplifier is 0.8m x 1.1 m which illustrates the degree of system compactness.