Theory of lineshapes for oblique-incidence Brillouin scattering by acoustic phonons

Abstract

Green functions are derived for the displacement gradients associated with the acoustic vibrations of an elastically-isotropic semi-infinite medium which has a single flat surface. The frequency dependence of the Brillouin-scattering cross section is calculated for arbitrary scattering angle and optical absorption length. The contributions of Rayleigh surface waves and of bulk acoustic waves modified by the presence of the surface are evaluated for some illustrative examples.