Observation of the second Stokes wave in a para-hydrogen Raman laser

Second Stokes wave generation has been demonstrated experimentally in a para-hydrogen multiple-pass cell pumped by the 9-micron CO2 lines. An output energy of 79 mJ has been achieved at 27 microns. Generation of the second Stokes wave is accompanied by a marked decrease in the first Stokes output; optimization of the optical design is necessary for generation of waves longer than 30 microns. The results of the study demonstrate the feasibility of further extending the wavelength coverage of para-hydrogen Raman lasers to the far infrared through second Stokes wave generation.