EFFICIENT VIBRATIONAL RAMAN CONVERSION IN O2 AND N2 CELLS BY USE OF SUPERFLUORESCENCE SEEDING

We report first-Stokes vibrational conversion efficiency of 21% and 35 %, respectively, in high-pressure O2- and N2-stimulated Raman cells. B roadband superfluorescence is employed to seed these Raman cells, sign ificantly increasing the conversion efficiencies with no measured effe ct on the Raman spectrum. The addition of helium buffer gas reduces co mpetition from stimulated Brillouin scattering and improves the pulse- to-pulse stability and spatial mode quality by increasing the thermal conductivity. Further improvement of the spatial mode quality is achie ved by use of gentle heating on the bottom of the cell to induce conve ction.