Abstract

The important influence of many-body Coulomb interactions on both the magnitude and dynamics of the nonlinear optical response of 2D excitons in high-quality GaAs quantum wells (QWs) has been demonstrated by many recent experimental and theoretical studies. Whereas this Coulomb coupling shoud be negligible for excitons excited in different wells of a multiple QW (MQW) structure for barrier thicknesses >10-15 nm, efficient inter-well exciton/exciton coupling via reemitted photons and light propagation effects has been recently predicted for very high quality samples. Here, we present dephasing measurements on excitons in MBE-grown GaAs MQW Bragg (and anti-Bragg) structures which consist of N identical QWs (width 20 nm, barrier material Al₀₃Ga_0.7As) with an equidistant separation d equal to one half (one quarter) of the heavy-hole exciton resonance wavelength λ in the medium, the experiments reveal effective dipole-dipole interactions between excitons excited in different wells mediated by the exchange of transverse photons.

© 1996 Optical Society of America