Backscattering enhancement of surface plasmons from multilayer rough surfaces

Backscattering enhancement is a phenomenon in rough surface scattering which manifests itself as a well-defined peak in the backscattering direction for certain media parameters. The study of backscattering enhancement is of tremendous interest to remote sensing and optics communities. In a small roughness regime, backscattering enhancement is induced by the excitations of surface plasmon waves along a certain path followed by retracing the same path in the reverse direction. In scattering from multilayer surfaces, only a few studies in the mechanisms of backscattering enhancement due to surface plasmon waves have been reported over the past decades. In the past works, the analysis of the incoherent and the coherent scattering physics of backscattering enhancement focused on the theoretical development of small perturbation methods to the second and forth orders. In this paper, an accurate solution to the two-dimensional scattering from multilayer rough surfaces based on extended boundary condition method (EBCM) and scattering matrix approach is presented, which in effect incorporates all orders of scattering. The criteria for backscattering enhancement using this method are discussed. Numerical simulations are performed on a dielectric slab deposited on a silver film and the emphasis is placed on the investigation of how layered rough interfaces affect the phenomenon of backscattering enhancement.