Theory of Brillouin scattering by Love waves

Abstract

Green functions are derived for the displacement gradients associated with transverse acoustic vibrations polarised parallel to the surface of a sample consisting of a plane parallel isotropic film deposited on an isotropic semi-infinite substrate. The frequency dependence of the corresponding Brillouin scattering cross section is calculated for arbitrary scattering angle. The spectrum includes contributions from the surface Love waves and from the higher-frequency bulk acoustic waves. Numerical calculations of Brillouin spectra are presented for a sample in which the substrate material is inactive in light scattering.