Nonlinear theory of lasing with or without inversion in a simple three-level atomic system

We investigate, using a nonlinear theory of laser physics, for a simple three-level atomic system the steady-state intensity behavior due to the effects of quantum coherence and decoherence. We find that a change from a noninversion laser to an inversion laser action can occur as the Rabi frequency of the driving field increases. The steady-state intensity of the laser field can arrive at a maximal value for a certain Rabi frequency of the driving field. We also find that the linear gain and the laser intensity tend to decrease for the linewidth of the driving field.