Nanosecond high-energy oscillator: regenerative amplifier excimer laser system

Energetic nanosecond UV sources could be advantageously used in laser material processing, biomedicine and to create laser - produced plasmas emitting soft X - ray radiation. SOPRA, in collaboration with IRPHE, is then developing an oscillator - regenerative amplifier XeCl laser system of short duration (1 - 3 ns), high energy and moderate divergence. Insertion in the amplification loop of the seed pulse and final extraction of the amplified laser pulse are realised by controlling the evolution .of its polarisation state by means of a HT driven Pockels cell and a half wave plate. The experimental results are discussed and compared to numerical ones issued from a code describing the amplification of the seed pulse in the active medium. Finally, it is shown that the maximum output peak power is fairly low, P-L similar to 1.4 MW (E-L similar to 4.8 mJ, tau(FWHM) approximate to 3.4 ns), due to important energetic loss as the highly divergent amplified beam is truncated by low - diameter aperture.