Exciton-Exciton Correlations in the Four-Wave Mixing Response of GaAs

Karl Leo

John Erland, D. Birkedal, Vadim G. Lyssenko +1 more

We investigate the spectral properties of the excitonic nonlinear response in a GaAs quantum-well sample containing wells of different thicknesses. We observe both the heavy-hole biexciton and the light-hole biexciton in the transient four-wave mixing spectrum and estimate their binding energy dependence on well width. For moderate excitation densities the signal for negative delay at the heavy-hole exciton and biexciton resonances is due to two-photon transitions to the biexciton states through the exciton states. The temporal behavior of the transient four-wave mixing signal from the heavy-hole exciton resonance is strongly dependent on the spectral position of the laser. We show that this effect is due to interference phenomena and to excitation-induced dephasing.

Atsushi Hasegawa, T.E. Kishimoto, Yasuyoshi Mitsumori +2 more

Bolton, Neukirch, D. S. Chemla +2 more

Yuri P. Svirko, T. Aoki, C. Ramkumar +2 more

Summary form only given. Four-particle correlation mediated by the Coulomb interaction has been found to play a major role in the nonlinear optical response at the semiconductor band edge at low excitation density. The attractive interaction of the excitons with opposite spins result in the formation of bound (bi-exciton) and unbound (scattered) two-exciton states. In this paper we report on the first to our knowledge, comparison of the contributions to the coherent nonlinearity from the bound and unbound two-exciton states. The polarization-sensitive four wave mixing experiment is performed in the high-Q semiconductor microcavity, in which the incoherent effects are suppressed due to strong exciton-photon coupling. The semiconductor microcavity has a single 12-nm-thick GaAs quantum well.

Mark C. Phillips, Hailin Wang