Subluminal and superluminal propagation in a three-level atom in the radiative limit based on coherent population oscillations

We investigate a three-level atomic system in the radiative limit to control the light propagation from the subluminal regime to the superluminal one. Here the three levels are connected between them by radiative transitions. We show that depending on the decay rates, this scheme, which is based on coherent population oscillations, allows to switch from one regime to the other by changing the Rabi frequencies of the driving fields. We also show that this scheme is also capable of producing absorptionless self-phase modulation.