title: Picosecond x-ray studies of coherent folded acoustic phonons in a multiple quantum well.
abstract: Coherent folded acoustic phonons in a multilayered GaSb/InAs epitaxial heterostructure were generated by femtosecond laser pulses and studied by means of ultrafast x-ray diffraction. Coherent phonons excited simultaneously in the fundamental acoustic branch and the first back-folded branch were detected. This represents the first clear evidence for phonon branch folding based directly on the atomic motion to which x-ray diffraction is sensitive. From a comparison of the measured phonon-modulated x-ray reflectivity with simulations, evidence was found for a reduction of the laser penetration depth. This reduction can be explained by the self-modulation of the refractive index due to photogenerated free carriers.
authors.affiliation: Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden. peter.sondhauss@fysik.lth.se
authors.forename: P
authors.initials: P
authors.lastname: Sondhauss
authors.forename: J
authors.initials: J
authors.lastname: Larsson
authors.forename: M
authors.initials: M
authors.lastname: Harbst
authors.forename: G A
authors.initials: GA
authors.lastname: Naylor
authors.forename: A
authors.initials: A
authors.lastname: Plech
authors.forename: K
authors.initials: K
authors.lastname: Scheidt
authors.forename: O
authors.initials: O
authors.lastname: Synnergren
authors.forename: M
authors.initials: M
authors.lastname: Wulff
authors.forename: J S
authors.initials: JS
authors.lastname: Wark