Abstract

Enhanced backscattering of light is reported in scattering from metallic diffraction gratings with random groove depths. The surfaces are fabricated in photoresist with a metallic overcoat and consist of evenly spaced grooves whose depths are statistically independent Gaussian variates. For several polarization states of the incident field, the Stokes parameters of the scattered light have been measured as functions of both incidence and scattering angle. Depending on the incidence and detected polarizations, some scattering measurements have diffraction orders like those found for a perfectly periodic surface, although other measurements contain purely enhanced backscattering, as found for random surfaces. These observations are discussed in terms of the Stokes matrix characterizing the scatterer. In particular, they are interpreted as being consistent with multiple-scattering and inconsistent with single-scattering theories. Extensions of this work will also address how the backscattering effects become associated with the grating orders of a perfect grating as the amount of depth fluctuation is reduced to zero.

© 1990 Optical Society of America