Coherent phonon-plasmon modes inGaAs:AlxGa1−xAsheterostructures

J. J. Baumberg, D. A. Williams
1996 Physical Review B (Condensed Matter)  
Time-resolved transient Kerr reflectivity was used to study coherent phonon-plasmon excitations in GaAs:Al x Ga 1Ϫx As heterostructures containing a two-dimensional electron gas. Ultrafast laser pulses of 65 fs duration were used in a balanced optical bridge to observe the oscillatory component of the reflectivity changes directly. This was found to be strongly dependent on the excitation photon energy, showing a crossover in the spectral amplitude of the longitudinal and
more » ... nsverse-optic-phonon frequencies as the excitation energy was varied. The energy dependence reflects variations in the phonon-plasmon coupling with depth, and hence local electron density, which is in very good agreement with recent predictions.
doi:10.1103/physrevb.53.r16140 pmid:9983517 fatcat:dtymnslbt5edvju4mzxz2t6nau