OBSERVATIONS OF BACKSCATTERING ENHANCEMENT FROM POLARITONS ON A ROUGH METAL-SURFACE

We present an experimental investigation of backscattering enhancement arising from the excitation of polaritons on a metal surface with highly one-dimensional random roughness. The surfaces are fabricated in gold-coated photoresist with methods in which a Gaussian random process is written into the surface through its randomly phased Fourier components. Backscattering enhancement is observed in the diffusely scattered light only in p polarization, and the narrow roughness spectrum of the surface confines the effect to a well-defined range of incident and scattering angles. The dependence of the diffuse scatter on the standard deviation of surface height and on the illumination wavelength is shown to provide an additional clear indication of the involvement of the surface polaritons.