EVIDENCE OF BIEXCITONIC CONTRIBUTIONS TO 4-WAVE-MIXING IN GAAS QUANTUM-WELLS

A three-pulse degenerate four-wave-mixing experimerlt and its theoreti cal analysis reveal contributions of local field and biexciton effects to the nonlinear optical response of the two-dimensional exciton. Qua ntum beats with a frequency equivalent to the biexciton binding energy appear only for specific polarizations. Polarization-dependent spectr ally resolved four-wave mixing shows an additional peak that is separa ted from the 1s heavy-hole exciton line by the biexciton binding energ y. These experimental results are in good agreement with the optical s election rules of the theoretical model, providing evidence for biexci tonic contributions to the four-wave mixing.