Rabi oscillations in a room-temperature quantum dash semiconductor optical amplifier

We report on a direct observation of coherent light-matter interactions imprinted on a short pulse propagating along a room-temperature, electrically biased, quantum dash semiconductor optical amplifier. The principle of the observation is that we characterize the complex field (phase and amplitude) of the short optical pulse after the interaction. By comparing the measurements to a numerical simulation, we are able to decipher the time evolution of effective two-state Schrödinger wave functions representing the ensembles of electronic states along the propagation path. The imprinted signatures on the pulse phase and amplitude stem from the accumulated propagation and reveal systematically clear Rabi oscillations and self-induced transparency. The high sensitivity to the effective ensemble states is shown to result from the response of the refractive index.