Macroscopic effects in stimulated Raman spectra

In stimulated Raman gain and loss spectra with the D1 line of an Rb-85 atomic vapor system we observe experimentally that as the detuning of the pump field becomes larger, a probe beam can exhibit a sharp transition from gain to loss. We use the dressed-state model to explain this phenomenon as the consequence of polarization interference between atoms of different velocities, which have competing contributions to the probe beam.