Frequency doubling multi-terawatt sub-picosecond pulses for plasma interactions

Frequency doubling a 140 X 110 mm 40 J sub-ps 1054 nm beam for laser matter interaction studies was investigated at the Central Laser Facility, with e fficiencies greater than 60% being achieved. The conversion characteristics (efficiency, beam quality, focusability, and pulse length) for two large 1 57 mm diameter aperture high quality KDP crystals of thickness 2 mm and 4 m m were studied. Using a fundamental drive beam of two times diffraction lim ited quality, focal spots of four times the diffraction limit in the freque ncy doubled beam were achieved and beam degradation effects shown to be min imal.