Observation of Velocity Bunching of Near-Zone-Edge Phonons in Semiconductors: An Intense, Tunable Phonon Source near 10 ÅA

Abstract

Experiments are reported on velocity bunching of near-zone-edge phonon pulses generated in the interband energy-relaxation process of photoexcited electron-hole pairs in GaAs and InP. The bunching is achieved by scanning the photoexcited region along the direction of phonon propagation at various velocities corresponding to different dispersive points on the phonon branch. This intense, tunable phonon source can be operated in the 10-ÅA wavelength region.