Evidence of density-dependent dephasing in interferometric four-wave-mixing experiments on heavy-hole excitons in ZnSe quantum wells

Temporal coherent-control experiments have been carried out on ZnSe quantum-well structures, We report on the transient four-wave-mixing (FWM) as well as on pump-and-probe (PP) experiments using, in both cases, a sequence of two phase-locked pulses and an additional incoming pulse. The PP measurements are used to directly time resolve the coherent control of the carrier dynamics. The observed FWM traces show an interference pattern with characteristic fine structures. They allow us to quantify effects beyond the third order of the non-linear susceptibility with respect to the optical field, The experimental results are in good agreement with calculations based on the semiconductor Bloch equations under addition of a phenomenological density-dependent dephasing. (C) 2002 Elsevier Science B.V. All rights reserved.