We study light diffraction in the periodically modulated ultrathin metal films both analytically and numerically. Without modulation, these films are almost transparent. The periodicity results in the anomalous effects, such as suppression of the transmittance accompanied by a strong enhancement of the absorptivity and specular reflectivity, due to the excitation of the surface-plasmon polaritons. These phenomena are opposite to the widely known enhanced transparency of periodically modulated optically thick metal films. Our theoretical analysis can be a starting point for the experimental investigation of these intriguing phenomena.
We show that surface electromagnetic waves (SEMWs) propagating along two-dimensional (2D) interfaces separating different metamaterials can behave analogously to 3D electromagnetic waves in either usual or left-handed media, depending on the permeabilities and/or permittivities of the two materials forming the interface. We derive the conditions when SEMWs carry energy opposite to the phase velocity. In analogy to three-dimensional (3D) left-handed media, we derive both an anomalous Cherenkov emission and a reversed Doppler effect. We also predict a negative refraction at the boundary between two different interfaces, which can be useful for perfect 2D lensing.
A theoretical study is presented on the optical transmission through square hole arrays drilled in optically thin films, where transmission may occur through both the holes and the metal layer. It is shown that, as the thickness of the metal film decreases, the coupling of light with short-range surface plasmons redshifts the extraordinary optical transmission peak to longer wavelengths. At the same time, the maximum-to-minimum transmittance ratio is kept high even for metal thicknesses as small as one skin depth.
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