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Proceedings Paper

Exciton coherence in GaAs quantum wells probed by four wave mixing measurements at high excitation intensities
Author(s): Bipul Pal; Arvind S. Vengurlekar
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Paper 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.

Paper Details

Date Published: 11 June 2002
PDF: 6 pages
Proc. SPIE 4643, Ultrafast Phenomena in Semiconductors VI, (11 June 2002); doi: 10.1117/12.470412
Show Author Affiliations
Bipul Pal, Tata Institute of Fundamental Research (India)
Arvind S. Vengurlekar, Tata Institute of Fundamental Research (India)

Published in SPIE Proceedings Vol. 4643:
Ultrafast Phenomena in Semiconductors VI
Kong-Thon F. Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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