Browsing by Subject "Evanescent wave"

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Open Access
Near-field light localization using subwavelength apertures incorporated with metamaterials
(Elsevier, 2012-03-12) Ates, D.; Cakmak, A. O.; Özbay, Ekmel
We report strong near-field electromagnetic localization by using subwavelength apertures and metamaterials that operate at microwave frequencies. We designed split ring resonators with distinct configurations in order to obtain extraordinary transmission results. Furthermore, we analyzed the field localization and focusing characteristics of the transmitted evanescent waves. The employed metamaterial configurations yielded an improvement on the transmission efficiency on the order of 27 dB and 50 dB for the deep subwavelength apertures. The metamaterial loaded apertures are considered as a total system that offered spot size conversion ratios as high as 7.12 and 9.11 for the corresponding metamaterial configurations. The proposed system is shown to intensify the electric fields of the source located in the near-field. It also narrows down the electromagnetic waves such that a full width at half maximum value of λ/29 is obtained.
Open Access
Two types of single-beam deflection and asymmetric transmission in photonic structures without interface corrugations
(Optical Society of America, 2016) Serebryannikov, A. E.; Colak, E.; Magath, T.; Özbay, Ekmel
We study single-beam deflection and asymmetry in transmission, two aspects of the same phenomenon that appear in the topologically simple, nonsymmetric, photonic crystal (PhC)-based structures without corrugations at the interfaces. Strong diffractions enabling efficient blazing, i.e., redistribution of the incident wave energy in favor of the desired higher diffraction order(s), can be achieved owing to the defect-like layer(s) embedded in a regular slab of PhC. The main features, together with the peculiarities of the two basic transmission types and relevant coupling and deflection scenarios, are discussed, for one of which a part of the PhC works in the evanescent-wave regime. Performances are suggested, in which efficient single-beam deflection and asymmetry in transmission can be obtained even when the irregular layer is deeply embedded. More than 97% of the incident wave energy can be converted into a single deflected beam that is associated with the first negative diffraction order, even though the entire structure is nonsymmetric and the diffractive element is located at some distance from the incidence interface.