EFFECT OF RANDOM SURFACE AND INTERFACE ROUGHNESS ON THE PROPAGATION OF SURFACE ACOUSTIC-WAVES

Weak random surface and interface roughness leads to a shift of the frequency and to damping of surface acoustic waves. In the framework of perturbation theory with a statistical description of the random roughness, a method is described for the calculation of the frequency shift and the damping constant in terms of the power spectrum of the roughness. It applies to homogeneous media as well as to layered structures and takes account of piezo-electricity. Calculations on the basis of this method require knowledge of the displacement field of the surface wave and the elastic Green tensor in the absence of surface and interface roughness. The method is then used to calculate numerically the damping coefficient of Rayleigh waves propagating at an oblique angle to the grooves of a random grating ruled on the surface of a homogeneous halfspace.