Anomalous Refraction in All-Dielectric Metagratings: The Finite Versus the Infinite Model

All-dielectric metagratings are considered, which are composed of two alternating materials and exhibit significant anomalous refraction. The optimal parameters for their efficient operation have already been determined by a rigorous integral equation method applied to the infinitely periodic structure. In this work, we seek to determine the sufficient length (sufficient number of inclusions) so that the anomalous refraction effects are stabilized and become clearly visible in the corresponding finite metagratings. Numerical results are reported for three different gratings, investigating the variations of the induced fields with respect to the overall length of each structure. It is shown that, particularly in the region below the central cells, only a small number of inclusions is needed for obtaining the desired refracted fields.