Amplification of an Ultra Short Pulse Laser by Stimulated Raman Scattering in a Low density Plasma Relevant to Pulse Compression

Experiments are described in which a 1mJ, 1ps, 1200 nm probe laser beam is amplified by interaction with an intersecting 350 J, 1ns, 1054 nm pump beam in a low density ({approx} 9 x 10{sup 24}/m{sup 3}) plasma. The transmission of the probe beam is observed to be enhanced by >{approx} 25 x when the plasma is near the resonant density for stimulated Raman scattering (SRS), as compared with measured transmissions at wavelengths just above the resonant value. The amplification is observed to increase rapidly with increases in both pump intensity and plasma density.