High-power forward Raman amplifiers employing low-pressure gases in light guides II Experiments

Abstract

An experimental study of a high-power forward Raman amplifier pumped by a multibeam KrF laser is presented. The active medium is either CH4 at 3-bar pressure or H2 at 1-bar pressure. As many as 56 pump beams confined in a light guide were combined into a single low-divergence Stokes beam. In CH4 a gain of up to 300 and a power-conversion efficiency of 70% was obtained. The maximum Stokes output energy was 8.4 J. The dependence of gain on pump bandwidth was investigated in H2. A gain of 500 and a conversion efficiency of 65% were obtained. The maximum output energy was 5.0 J.