Observation of Selényi rings in the diffraction patterns of layered samples with periodic arrays of cylindrical structures.

We present an experimental and numerical study of the optical properties of nanofabricated samples with layered dielectric structures. The samples, which contain periodic arrays of silicon disks over a flat layer of silicon dioxide on a silicon substrate, present diffraction and thin film interference effects. Well-defined circular fringes that modulate the intensity of the diffraction orders are observed in the far-field angular distribution of scattered light. We also find that although the angle of incidence modulates the intensity of the observed circular ring patterns, it has little or no effect on their angular position. The problem is modeled theoretically through numerical calculations based on a Rayleigh method.