Role of exciton-exciton interaction on resonant third-order nonlinear optical responses

Weakly interacting boson model with the account for the bound biexciton is employed to obtain the evolution equations for the macroscopic exciton pola rization. The polarization-sensitive degenerate four-wave mixing measuremen ts in frequency domain enable us to estimate the relative contribution of t he bound biexciton stale on the nonlinear optical response. In the time-dom ain measurements, we study the amplitude and phase of the beating in the ti me-integrated four-wave mixing signal. On the basis of the developed evolut ion equations, we show that the phase shift of the beating signal is polari zation sensitive and is determined by the interplay between excitation-indu ced dephasing, exciton-exciton interaction and other mechanisms of the nonl inearity, (C) 2000 Published by Elsevier Science B.V. All rights reserved.