Anomalous linewidth of driven Mollow lasers

An anomalous linewidth is predicted to appear in a driven Mellow laser. The linewidth does not simply decrease as the laser intensity increases, but displays a local minimum and maximum. The maximal linewidth does not necessarily correspond to the maximal population in the excited lasing level but to the minimal population. Employing the dressed picture, we separate the population component of the linewidth from the coherence component. It is identified that quantum coherence is responsible for the linewidth anomaly. We isolate two irreversible pathways of population pumping and show that the coherence effects are ultimately determined by the population pumping through the two irreversible pathways.