The diffraction of electromagnetic waves at the surface periodic structures accompanied by strong anomalous effects in different diffraction orders is considered in detail for high-contrast interfaces. We restrict discussion by the transverse magnetic polarization of the incident wave (the magnetic field is orthogonal to the plane of incidence) and the simplest geometry when the plane of incidence is orthogonal to the grating grooves. The most attention is devoted to the strong maxima and minima of the energy flux density accompanying specific grazing propagation of some diffraction order. Relation to other anomalies, both Rayleigh and the resonance ones is discussed as well.
We restrict consideration to interface of two homogeneous isotropic nonmagnetic media, say, metal and dielectric. If between these two media exists some third one (even very thin layer), then additional to SPP resonances can occur.7 For anysotropic media the resonance can be caused by other than SPP surface modes, say, Dyakonov ones, see Ref. 8 and citations therein.
Noteworthy, in the simplest geometry the diffraction of TE and TM components of the incident wave become independent processes and thus can be considered separately.
The following considerations can be applied to the case of plane surface of metamaterials with periodically modulated electromagnetic properties so that the surface impedance is space-periodic, ξ= ξ(x) , ξ(x + d) =ξ(x) , cf.11–13
Alternative case is of interest also, resulting in strong GA as well. The specific case when GA is accompanied by SPP anomaly relating to some other diffraction order is also of interest. These cases correspond to the double and combined anomalies and will be considered in forthcoming papers.
Specifically, such condition holds within approximation of ideal metal that is valid in the long wavelength region (low frequency).