Abstract
Ultrafast laser excitation of an superlattice (SL) creates coherent folded acoustic phonons that subsequently leak into the bulk (InP) substrate. Upon transmission, the phonons become “unfolded” into bulk modes and acquire a wave vector much larger than that of the light. We show that time-resolved x-ray diffraction is sensitive to this large-wave vector excitation in the substrate. Comparison with dynamical diffraction simulations of propagating strain supports our interpretation.
- Received 6 May 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.025505
©2008 American Physical Society