Coherent acoustic phonons in semiconductor Bragg mirrors

We report on the investigation of coherent acoustic phonons in semiconductor Bragg mirrors by means of femtosecond pump-probe spectroscopy. The observed acoustic mode spectrum is based on the phonon dispersion relation of the material, which is backfolded into the mini-Brillouin zone of the periodic structure. We show that the structural parameters can be determined by an all optical method with high accuracy.