Scattering of s -polarized plane waves by finite-thickness periodic structures made of ultralow-permittivity metamaterials

摘要

Scattering of s-polarized plane waves by finite-thickness periodic structures is studied, which contain components made of ultralow-permittivity metamaterial (ULPM), and therefore exhibit intermediate properties between those made of pure metals and of pure dielectrics. The numerical results presented demonstrate basic frequency- and angular-selectivity-concerned effects arising in the structures with sinusoidal corrugations, which are made of ULPM, and for a stack of two such periodic structures, in which one of them is made of ULPM and the other one of a dielectric. The results presented are mostly related to the zero-permittivity case, when there is no wave propagating in the transverse direction within the metamaterial. The field inside ULPM is either close to or exactly the static one. For the structures of the first type, this can lead to a straightening of the field lines at the lower (noncorrugated) interface and, in turn, to a suppressing of higher modes (Bragg beams) in the transmitted field, which are allowed to propagate. The known property of a zero-permittivity noncorrugated slab, i.e., the cutoff-type frequency dependence of the transmittance, appears also for corrugated periodic structures studied in both single- and multimode regimes. In our study, a similar behavior vs the angle of incidence is demonstrated and a condition for its appearance is given. For the structures of the second type, it is shown that these effects can be combined with those, which are typical for dielectric gratings and usually associated with bulk and surface modes. Stacking ULPM and dielectric layers can also lead to an enhancement of some effects, which are inherent to each of the layers, as well as to several abnormal effects. The effects found promise to be useful for controlling and, in particular, for splitting/combining of light and microwave radiation.