Coherent acoustic phonons in GaAs/AlAs superlattices

Coherent zone-folded acoustic phonons are generated in GaAs/AlAs superlattices by excitation with femtosecond laser pulses. Three modes of first and second backfolded order are driven by resonant impulsive stimulated Raman scattering in forward and backward directions. The coherent vibrations are analyzed in a time resolved detection measurement and compared with Raman scattering cross sections