Experimental and modeling studies of a Brillouin amplifier

KrF laser-pumped backward Brillouin amplification of nanosecond pulses at 248 nm is investigated both experimentally and numerically. Gain and saturation of the amplifier system are studied for an SF/sub 6/ Brillouin medium at pressures of 5 to 15 atm and 24 ns pump pulses at an intensity of approximately=9 MW/cm/sup 2/. The input Stokes intensity is varied from 0.001 to 1.0 MW/cm/sup 2/. Power gains of 20 are achieved at energy extraction efficiencies of 40%. Experimental results are compared to a time dependent numerical model of pulse amplification which incorporates arbitrary pump and Stokes pulse shapes and intensities. The effect of laser bandwidth is investigated in the model calculations in order to assess its influence on Brillouin amplification.<
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