Microscopic Theory of Rabi Flopping, Photon Echo, and Resonant Pulse Propagation in Semiconductors

The phenomena of Rabi oscillations, resonant pulse propagation, and photon echo in semiconductors are investigated by numerically solving the full semiconductor Bloch equations for the example of bulk CdSe. The calculations are done for resonant femtosecond excitation at the exciton resonance. The many‐body modifications of Rabi flopping and semiconductor photon echo are discussed for a thin medium, whereas the propagation of weak and strong pulses is analyzed for an extended material. Rabi flopping of the density can lead to field reamplification and thus to long propagation distances of sufficiently strong pulses and to pulse break‐up. The area theorem known from self‐induced transparency (SIT) in atomic systems is generalized for the case of phase modulated fields and shown to be modified significantly in semiconductors. Even though no ideal SIT occurs, the Coulomb interacting electron–hole system nevertheless seems to support extremely long propagation distances of so‐called π‐pulses.