Exciton coherence in GaAs quantum wells probed by four wave mixing measurements at high excitation intensities

Bipul Pal; Arvind S. Vengurlekar

doi:10.1117/12.470412

11 June 2002 Exciton coherence in GaAs quantum wells probed by four wave mixing measurements at high excitation intensities

Bipul Pal, Arvind S. Vengurlekar

Author Affiliations +

Proceedings Volume 4643, Ultrafast Phenomena in Semiconductors VI; (2002) https://doi.org/10.1117/12.470412
Event: Symposium on Integrated Optoelectronic Devices, 2002, San Jose, California, United States

Abstract

We perform two beam time integrated (TI) degenerate four wave mixing (DFWM) measurements on 8~nm GaAs quantum wells (QW). Pulses from a Ti-Sapphire laser resonantly excite only 1s heavy hole excitons. The power density of the leading pulse (I₁) is increased, keeping that of the delayed pulse fixed and relatively small. We measure the TI-DFWM signal at different delays as well as the DFWM spectra at a fixed delay, as I₁ is increased. We find that the dephasing rate, after an initial increase with I₁, becomes independent of I₁ for large I₁. The spectrally integrated DFWM signal, which probes the coherent polarization of the resonantly excited QWs, initially increases with I₁, reaches a peak and then decreases as 1/(root)I₁ at large I₁. The results are compared with theoretical models of exciton coherence.

Citation Download Citation

Bipul Pal and Arvind S. Vengurlekar "Exciton coherence in GaAs quantum wells probed by four wave mixing measurements at high excitation intensities", Proc. SPIE 4643, Ultrafast Phenomena in Semiconductors VI, (11 June 2002); https://doi.org/10.1117/12.470412

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