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Active research into nanoscience and nanotechnologies that are available for nano fabrication have lead to considerable
progress in the understanding of the optical properties of metals on nanometer scale. Here, noble-metal strip-like
nanostructures are attractive objects of research. Indeed, they can be easily manufactured and serve as building blocks of
optical nanoantennas and sensors with unique geometry-dependent optical properties. This is because they display
intensive localized surface-plasmon resonances in the visible and far-infrared ranges that lead to near- and far-field
enhancement effects. Thanks to surface-plasmon resonances, multi-element finite gratings have attractive properties of
extraordinarily large reflection, absorption, and transmission, depending on the arrangement of the elementary cell of the
grating. All these phenomena are greatly influenced by the so-called grating resonances which appear due to periodicity.
The 2D modeling of electromagnetic wave scattering by thin noble-metal nanosize strips and their finite-periodical
ensembles arranged in comb-like gratings is considered. Our analysis is carried out using new efficient, convergent and
accurate method. It is based, first, on the use of the generalized boundary conditions (GBC) valid for a thin and highcontrast
material layer; they allow us to consider only the limit values of the field components and reduce integration
contour to the collection of corresponding strip median lines. Second, for the building of discrete model of the obtained
singular integral equations, we use very efficient Nystrom-type algorithm with quadrature formulas of interpolation type.
We study the SPRs of the finite periodic comb-like strip ensembles versus the incidence angle of the plane
electromagnetic wave and the strip characteristics; both near-field and far-field properties of the associated surfaceplasmon
resonances and especially local field enhancements or focusing effects are analyzed. Moreover, we investigate
the periodicity-induced properties such as the grating resonances in the context of the development of optimal design
strategies for efficient multi-strip optical nanoantennas
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