SCATTERING OF LIGHT FROM RANDOM SURFACES THAT ARE PERIODIC ON AVERAGE

We study the scattering of p-polarized light from a one-dimensional ra ndomly rough metal surface that is periodic on average, rather than pl anar. We find that the contribution to the mean differential reflectio n coefficient from the diffuse component of the scattered light displa ys features, e.g., dips, at scattering angles theta(s) given by sin th eta(s) = -sin theta0 + n(lambda/d), where theta0 is the angle of incid ence, n is a nonzero integer, lambda is the wavelength of the incident light, and d is the period of the average surface, in addition to the enhanced backscattering peak at theta(s) = -theta0. These additional features are caused by the interference of each multiply scattered sur face-plasmon polariton path with its time-reversed partner.