| Backscattering enhancement arising from the excitation of plasmon polaritons on metal surfaces with highly one-dimensional random roughness is studied experimentally. Holographic techniques used to manufacture diffraction gratings are extended to multiple periods and applied to the fabrication of surfaces with the required power spectrum and height statistics. A backscattering peak is observed in the diffusely scattered light, and a series of experiments demonstrate that the dependence of the observed effect on polarization, the angles of incidence and scattering, the rms roughness, and the incident wavelength agree with calculations using a perturbation theory that is exact to fourth order in the surface profile. Further experiments demonstrate the existence of the effect for a deterministic surface, the suppression of surface plasmon polaritons by the superposition of a grating onto the random roughness, and the angular correlations of the scattered light. Finally, a strong backscattering effect that is beyond the limits of the theory is isolated; the necessary sixth-order term of the perturbation theory is developed, evaluated, and successfully compared to the experimental observations. |
