Efficient sum-frequency and second harmonic generation in a two-pass copper vapour laser amplifier

New results are presented on the efficient generation of UV radiation by using nonlinear DKDP and BBO crystals and a two-pass copper vapour laser amplifier with the enhanced peak power. The average power (average optical efficiency) of laser radiation at the sum frequency (λ = 0.271 μm) was 3.6 W (24%) for the BBO crystal and 2.1 W (14%) for the DKDP crystal. The maximum average second-harmonic power generated by using the BBO crystal was 3.4 W (44%) at 0.289 μm and 2.1 W (27%) at 0.255 μm.