RELIABLE STIMULATED BRILLOUIN-SCATTERING COMPRESSION OF ND-YAG LASER-PULSES WITH LIQUID FLUOROCARBON FOR LONG-TIME OPERATION AT 10 HZ

Stokes pulses of high energy and high-average power were obtained by s timulated Brillouin scattering (SBS) compression of long Nd:YAG laser pulses. The SBS medium used in the single-cell compressor was liquid u ltrafiltered Fluorinert FC-75 fluorocarbon. An output pulse duration o f 0.9 ns and a peak-power enhancement by 1 order of magnitude were obs erved for 10-ns, 0.57-J input pulses at a 10-Hz repetition rate. The c ompressor internal SBS efficiency reached a value of eta(SBS) = 94% an d the overall device efficiency a value of eta(dev) = 87%; both values are the highest reported so far to the best of our knowledge. The sim ple single-cell SBS geometry provided excellent energy and pointing st ability of the Stokes pulse. Its temporal shape turned out to be somew hat less stable. The SBS process also partially improved the laser bea m quality. The Stokes pulses proved to be capable of generating radiat ion in the extreme-ultraviolet and soft-x-ray regions over a period of two months without any significant output deterioration. (C) 1998 Opt ical Society of America.