Experimental benchmarking of the code for Yb:YAG multi-slab gas-cooled laser system operating at cryogenic temperatures

We present benchmarking of the home-made MATLAB model with the experimental data obtained for the 10 J/10 Hz cryogenically cooled multi-slab laser systems being developed in the Rutherford Appleton Laboratory, STFC, UK. The laser head of each system consists of four, 5 mm thick slabs separated by 2 mm gaps. Each slab is composed of 35 mm diameter Yb:YAG active material surrounded by 10 mm thick absorptive cladding. The slabs are pumped from both sides by diode arrays which in total deliver up to 40 kW of pump power in 1 ms pulses with a central wavelength of 940 nm, bandwidth 6 nm and pump spot 20 mm x 20 mm. The laser head has been modeled to predict gain in the slabs and the amplification of the seed beam for the temperatures of operation ranging from 100 K to 180 K. Output energy for different pump pulse durations has been calculated. It was determined that the maximum output energy obtained after 6 passes for the amplifier operating at the temperature of 120K and repetition rate 1 Hz was 9 J for the seed energy of 20 mJ. For higher temperature of 160 K the output energy was 8 J. The corresponding maximum single pass gain in the amplifier head was 8 for 120 K and 4 for 160 K. Results of the simulations are in a very good agreement with the measured data presented in [1].