Standing optical phonons in finite semiconductor superlattices studied by resonant raman scattering in a double microcavity

We report optical double resonant enhancement of Raman scattering in a new double microcavity geometry. The design allows almost backscattering geomet ries, providing easy access to the excitations' in-plane dispersion. The ca vity is used to study the phonon spectra of a finite GaAs/AlAs superlattice . A new type of "standing optical vibration" is demonstrated involving the GaAs confined phonons with a standing wave envelope determined by the super lattice thickness. A strong dispersion of the first order standing wave mod e is observed, as well as its anticrossing with higher order confined modes of the same symmetry.