N2 Laser Frequency Conversion by Stimulated Raman Scattering in H2

igh-efficiency frequency conversion in H2 of a nitrogen laser oscillator-amplifier system is described. The laser system provides about 1 MW output power with a very low intrinsic divergence. Up to 3 Stokes lines at 392, 468, and 581 nm and 3 Anti-Stokes at 296, 263, and 237 nm, respectively, have been observed at the output of the 60 cm long H2 Raman cell. Peak power values of 500, 300, and 70 kW have been measured for the first 3 Stokes, respectively, corresponding to a 56% pump energy conversion efficiency. A comparison between free and guided propagation (in a hollow dielectric waveguide) is also reported, for various values of the pump intrinsic divergence.