Browsing by Subject "Fixed angles"

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    Experimental validation of strong directional selectivity in nonsymmetric metallic gratings with a subwavelength slit
    (American Institute of Physics, 2011-02-02) Cakmakyapan, S.; Caglayan, H.; Serebryannikov, A. E.; Özbay, Ekmel
    Strong directional selectivity is theoretically predicted and experimentally validated at the microwave frequencies in the beaming regime for a single subwavelength slit in nonsymmetric metallic gratings with double-side corrugations. The operation regime can be realized at a fixed angle of incidence when the surface-plasmon assisted transmission is significant within a narrow range of observation angles, if illuminating one of the grating interfaces, and tends to vanish for all observation angles, if illuminating the opposite interface. The studied effect is connected with asymmetry (nonreciprocity) in the beaming that occurs if the surface plasmon properties are substantially different for the two interfaces being well isolated from each other.
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    Unidirectional transmission in photonic-crystal gratings at beam-type illumination
    (Optical Society of American (OSA), 2010) Cakmak, A.O.; Colak, E.; Serebryannikov, A.E.; Özbay, Ekmel
    Unidirectional transmission is studied theoretically and experimentally for the gratings with one-side corrugations (non-symmetric gratings), which are based on two-dimensional photonic crystals composed of alumina rods. The unidirectional transmission appears at a fixed angle of incidence as a combined effect of the peculiar dispersion features of the photonic crystal and the properly designed corrugations. It is shown that the basic unidirectional transmission characteristics, which are observed at a plane-wave illumination, are preserved at Gaussian-beam and horn antenna illuminations. The main attention is paid to the single-beam unidirectional regime, which is associated with the strong directional selectivity arising due to the first negative diffraction order. An additional degree of freedom for controlling the transmission of the electromagnetic waves is obtained by making use of the asymmetric corrugations at the photonic crystal interface. © 2010 Optical Society of America.