Quantum Beat Between Exciton and Continuum States in a 500 mm Undoped GaAs

Joaquín Fernández-Rossier, C. Tejedor, Roberto D. Merlin

W. A. J. A. van der Poel, A. L. G. J. Severens, C. T. B. Foxon

T. Dekorsy, A. M. T. Kim, G. C. Cho +5 more

Quantum beats of heavy and light holes in GaAs quantum wells are investigated in femtosecond time-resolved four-wave mixing and transmission experiments as a function of optical excitation energy. Under nonexcitonic excitation conditions, the four-wave mixing signal disappears due to the immediate loss of the interband coherence of continuum states. In the transmission experiment, the quantum beats are observed up to excess energies of 75 meV above the exciton resonances. The experimental data clearly demonstrate the coherence of continuum states in the valence band. Changes of the beat frequency with the excitation energy are due to the dispersion of the valence bands.

Karl Leo, Ernst Otto Göbel, Theo C. Damen +6 more

Satoshi Ideshita, Yasuaki Masumoto

We present the detailed experimental results of the time-resolved nonlinear luminescence of excitons in undoped GaAs-AlAs quantum wells. The observed nonlinearity results from the saturation in luminescence originated from the phase space filling and exchange effects of carriers. In some temporal profiles of nonlinear luminescence, anomalous anti-correlation profile has been observed. The origin of anti-correlation is ascribed to be the finite rise time of the exciton population at the luminescent tail state in the exciton band.

Martín Koch, G. von Plessen, Jochen Feldman +1 more