A new configuration of the one-dimensional reflective asymmetrical metallodielectric grating structure for unidirectional
excitation of surface plasmon polaritons (SPPs) is proposed. The structure is embedded between two different dielectric
media and composed of two 1D metallic gratings each of the two consisted of periodically placed rectangular metal
stripes. The case of normal incidence is analysed. It is shown that even a small horizontal shift between these two layers
or a change in dielectric contrast of the grating fillings, the structure may redirect an energy flow of the SPP in the near
field. An explanation of this unidirectional SPP excitation is given. Besides the SPP excitation by a plane wave, the
excitation by a finite-diameter 3D Gaussian beam is analysed as well, as the beam facilitates visualisation of the SPP
finite propagation length and efficiency of the directivity switch. It is shown that the switching phenomenon exists
together with a high concentration of the electromagnetic field at the structure, the feature especially desirable in
techniques of subwavelength nanovisualisation. The configurations analysed may be also useful in designing optical
devices as optical switches, VLSI devices, light harvesting photodetector structures or, in general, in any case where
efficient control of energy propagation directivity is of primary importance.
Behaviour of Laguerre{Gaussian beams (optical vortices are their attributes) impinged at a dielectric interface
under distinct angles is discussed. For different incident angles the beams interact with the interface differently.
Two ranges of incident angles, specified by diverse optical vortices excitation which is caused by cross-polarization
effect, is analyzed. "Significant" boundary between these two ranges is defined. Theoretical analyses are confirmed
by numerical simulations.
Excitation and cancellation of higher-order elegant Hermite-Gaussian and Laguerre-Gaussian beams under normal incidence at isotropic, lossless, dielectric interfaces are analysed. It is shown that such phenomena are originated in the cross-polarization coupling between orthogonal polarization components of the beams and depend qualitatively on interrelations between beam field spatial distribution and beam polarization. For Laguerre-Gaussian beams these interrelations associate beam orbital and spin angular momenta. Analytic description confirmed by numerical simulations is given for transmission of two types of beams: Hermite-Gaussians of linear polarization and Laguerre-Gaussians of circular polarization.
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