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Proceedings Paper

Phonon and polariton dynamics and the existence of long-lived acoustic phonons
Author(s): Walter E. Bron; Tibor Juhasz
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Paper Abstract

Coherent states of optical phonons and polaritons are created through coherent Raman excitation (CRE) and their dephasing is determined through pico- and femtosecond time resolved coherent anti-Stokes Raman spectroscopy (TRCARS). The temperature dependence of the dephasing is used to identify the acoustic phonons generated from the decay of coherent optical states. The general decay channel involves the decay of the optical phonons and polaritons into two acoustic phonons each with one half the optical phonon energy and with compensating wave vectors. In some cases the decay channel is more complicated. In order to conserve momentum one of the phonons is near the positive X-point and the other near the negative X-point of the Brillouin zone. The TA phonon is on the lowest dispersion branch and, therefore, cannot further decay into lower energy phonons and still obey energy and momentum conservation. Thus to third order in the decay kinetics the TA phonons should have infinite lifetime. Our observations lead to a TA phonon lifetime of 66.5 +/- 5 ns.

Paper Details

Date Published: 6 May 1994
PDF: 16 pages
Proc. SPIE 2142, Ultrafast Phenomena in Semiconductors, (6 May 1994); doi: 10.1117/12.175885
Show Author Affiliations
Walter E. Bron, Univ. of California/Irvine (United States)
Tibor Juhasz, Univ. of California/Irvine (United States)

Published in SPIE Proceedings Vol. 2142:
Ultrafast Phenomena in Semiconductors
David K. Ferry; Henry M. van Driel, Editor(s)

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