Multi-photon gain resonances and associated lasing in coherently-driven potassium atoms

This study presents a more complete and wider ranging theoretical study of the amplification and lasing possibilities in alkaline atoms that takes advantage of the multiplicity of hyperfine and magnetic sublevels involved in the ³⁹K 4S₁2/-4P₁2/ transition. Using drive and probe fields of appropriate polarizations and propagation directions, and optically pumped atoms, (n+m) multi-photon resonances involving absorption of n drive photons and simultaneous emission of m probe photons can be generated. Theoretical predictions are in good agreement with experimental findings.