Noise suppression and enhanced focusability in plasma Raman amplifier with multi-frequency pump

Laser pulse compression-amplification through Raman backscattering in plasmas can be facilitated by using multi-frequency pump laser beams. The efficiency of amplification is increased by suppressing the Raman instability of thermal fluctuations and seed precursors. Also the focusability of the amplified radiation is enhanced due to the suppression of large-scale longitudinal speckles in the pump wave structure. (C) 2003 American Institute of Physics.