Efficient anti-Stokes Raman conversion by four-wave mixing in gases

We describe a means for efficient, energy-scalable generation of first-order anti-Stokes light by four-wave mixing, using collimated pump and first-order Stokes seed beams. We performed a one-dimensional, plane-wave analysis of the process, assuming steady-state conditions and monochromatic beams. A prescription for designing the optimum anti-Stokes converter with this technique is derived from this analysis, and we show that energy conversion efficiencies from pump light to anti-Stokes light of ~30% might be possible. We also report an unoptimized, proof-of-concept experiment that produced 40 mJ of anti-Stokes-shifted light at 432 nm from 1.2 J of 527-nm pump light in a 60-cm-long hydrogen cell.