High Efficiency 10 J Diode Pumped Cryogenic Gas Cooled Yb:YAG Multi-Slab Amplifier

We report on the first demonstration of a diode pumped, gas cooled, cryogenic multi-slab Yb:YAG amplifier. The performance was characterised over a temperature range from 88 K to 175 K. A maximum small-signal single-pass longitudinal gain of 11.0 was measured at 88 K. When amplifying ns-pulses, recorded output energies were 10.1 J at 1 Hz in a 4-pass extraction geometry and 6.4 J at 10 Hz in a 3-pass setup, corresponding to optical-to-optical conversion efficiencies of 21 % and 16 %, respectively. To our knowledge, this represents the highest pulse energy so far obtained from a cryo-cooled Yb-laser and the highest efficiency from a multi-J DPSSL system.