Inversionless amplification in three-level systems: Dressed states quantum interference and quantum-jump analyses

We investigate amplification without inversion (AWI) in different three-level systems driven by an on-resonance coherent field and identify the elements that contribute to destructive or constructive dressed states quantum interference in the probe field absorption spectrum. We determine analytically the conditions for AWI at the probe field line center and at the wings of the resonance region. For this latter case, we explicitly locate the position of the maximum gain as a function of the probe field detuning. Finally, through a quantum-jump analysis, we find that AWI at the wings of the resonance region is due to an asymmetry between one-photon-stimulated emission and absorption processes, in contrast with AWI at the line center which arises from the contribution of two-photon gain. © 1998 Elsevier Science B.V. All rights reserved.