High-energy gradient doped Yb:YAG thin slab laser amplifier

A concept of compact, scalable and reliable solid-state amplifier based on thin slab is proposed. It combines the following features: single pass pump and signal propagation without internal reflections; use of a gradient doped thin-slab AE; beam guiding effect pre-compensation. The direct passage of the radiation allows to obtain a high quality of the beam (M2⪅1.4). Thin slab geometry and gradient doping provide excellent heat dissipation and low heating (30 °C at 500 W pumping power). The amplification of stretched and pre-amplified femtosecond radiation reached 3.6 (with input of 6 mJ) at a pump power of 500 W, so output energy was 22 mJ at 1.5kHz. A further increase in the output energy is possible according to calculations, up to 100 mJ, which is limited by the breakdown threshold of the output end at a pump power of 1 kW.