THZ RADIATION FROM COHERENT POPULATION-CHANGES IN QUANTUM-WELLS

We identify the contributions to the terahertz (THz) signals from both the creation of polarized uncorrelated electron-hole pairs and polari zed excitons in GaAs/Al0.3Ga0.7As quantum wells. We find that the THz radiation from the creation of polarized excitons is comparable in mag nitude to that from the creation of polarized uncorrelated e-h pairs. Unlike the THz transient from uncorrelated e-h pairs, the signal from polarized excitons is also strongly influenced by the combined effects of detuning and finite pulse duration.