  The coherent folded longitudinal acoustic phonons (FLAPs) in gold
nanoparticles (NPs) imbedded InGaN/GaN sample have been studied using
degenerate pump-probe technique. When the FLAPs are generated within the
multiple quantum wells, the zone-center FLAPs extending from multiple quantum
wells is detected in the GaN and sapphire substrate. Up to five phonon modes
are clearly observed and they are well explained by the back and forth
propagation of the signal phonon wave packet in the InGaN/GaN quantum wells.
The results are consistent with similar measurements to GaAs/AlAs
superlattices.
