Superradiance and photon echo effects in the interaction of coherent optical pulses with inhomogeneously broadened systems

A theoretical analysis is given of the phenomena of superradiance and photon echo in the interaction of coherent light pulses with a resonant medium emitting inhomogeneously broadened lines. A delay of the superradiance signal is predicted. The properties of the response function of a two-level system and of the photon echo are considered.