Time-resolved interference of coherent polarization waves in semiconductors

We experimentally show that coherent transients can be investigated in any kind of material systems by means of simple interferometric technique with a time resolution limited only by the pulse duration. The measurement, as a function of the time delay between two excitation pulses, of the time-integrated signal related either to the absorbed energy or to the resonant elastic light scattering allows a straightforward determination of the coherence status of the system. Demonstrative experiments in GaAs bulk samples and in GaAs/AlGaAs quantum well structures are reported.