EXPONENTIAL GAIN IN RESONANT 4-WAVE-MIXING VIA DRESSED INVERSIONS

High-efficiency coherent high-frequency generation via resonant four-w ave mixing is investigated in a dressed stales analysis of a bichromat ically driven three-level system. We propose the existence of exponent ial gain due to population transfer at the anticrossings of closely sp aced inverted dressed states. This occurs when the Rabi frequency of t he weaker detuned driving field is much smaller than the leading reson ant Rabi frequency and simultaneously comparable to the largest atomic relaxation rate. The dressed population inversion and thus the expone ntial gain is not affected until the generated field becomes comparabl e in intensity to one of the two applied fields. when saturation may t ake place. The analysis is applied to a krypton configuration of inter est to current experiments. [S1050-2947(98)07302-8].