Efficient second harmonic generation of a high-power picosecond CO 2 laser

A comparative analysis of AgGaSe , GaSe, CdGeAs , and Te for second harmonic generation (SHG) of a picosecond CO laser at intensities up to 50 GW/cm is presented. We demonstrate external energy conversion efficiency of >20% in AgGaSe . Conversion efficiency >5% is measured in GaSe and CdGeAs . Self-focusing and multifilamentation are found to severely limit the SHG process in CdGeAs and Te at such high fields. Demonstration of ≥150 MW SH pulses for a 10 m picosecond pump, in combination with femtosecond CO laser development, will open new strong-field applications in the 4.5-5.5 m range.