Browsing by Author "Serebryannikov, A.E."

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Open Access
Multichannel optical diode with unidirectional diffraction relevant total transmission
(Optical Society of American (OSA), 2012) Serebryannikov, A.E.; Cakmak, A.O.; Özbay, Ekmel
We will show that broadband unidirectional optical transmission with a total transmission maximum inside the band can be obtained for linearly polarized incident waves in the nonsymmetric photonic crystal gratings made of isotropic linear materials at a fixed nonzero or zero angle of incidence. Being based on the merging of diffraction and dispersion effects, the basic physical mechanism studied exploits the transmission channels associated with higher orders, for which asymmetry in the coupling conditions at the two grating interfaces appears when spatial inversion symmetry is broken. Total transmission in one direction and zero transmission in the opposite direction can be obtained due to hybridization of Fabry-Perot type resonances with a diffraction anomaly that yields a diode-like operation regime. Single-beam deflection and two-beam splitting can be obtained, for which transmission can be (nearly) total, if the corrugated side is illuminated. In contrast to the previous studies, it is also shown that unidirectional transmission can appear only at a fixed frequency and only due to diffractions, when total transmission occurs at the noncorrugated-side illumination, being in agreement with the Lorentz Lemma. © 2012 Optical Society of America.
Open Access
Multifunctional blazed gratings for multiband spatial filtering, retroreflection, splitting, and demultiplexing based on C2 symmetric photonic crystals
(AIP Publishing LLC, 2022-06-08) Serebryannikov, A.E.; Skigin, D.C.; Vandenbosch, G.A.E.; Özbay, Ekmel
The concept of multifunctional reflection-mode gratings that are based on rod-type photonic crystals (PhCs) with 𝐶2 symmetry is introduced. The specific modal properties lead to the vanishing dependence of the first-negative-order maximum on the angle of incidence and the nearly sinusoidal redistribution of the incident-wave energy between zero order (specular reflection) and first negative diffraction order (deflection) at frequency variation. These features are key enablers of diverse functionalities and the merging of different functionalities into one structure. The elementary functionalities, of which multifunctional scenarios can be designed, include but are not restricted to multiband spatial filtering, multiband splitting, retroreflection, and demultiplexing. The proposed structures are capable of multifunctional operation in the case of a single polychromatic incident wave or multiple mono-/polychromatic waves incident at different angles. The generalized demultiplexing is possible in the case of several polychromatic waves. The aforementioned deflection properties yield merging demultiplexing with splitting in one functionality. In turn, it may contribute to more complex multifunctional scenarios. Finally, the proposed PhC gratings are studied in transmissive configuration, in which they show some unusual properties.
Open Access
Non-ideal cloaking based on Fabry-Perot resonances in single-layer high-index dielectric shells
(Optical Society of American (OSA), 2009) Serebryannikov, A.E.; Usik P.V.; Özbay, Ekmel
Strong reduction of the scattering cross section is obtained for subwavelength dielectric and conducting cylinders without any magnetism for both TE and TM polarizations. The suggested approach is based on the use of Fabry-Perot type radial resonances, which can appear in single-layer, high-ε, isotropic, and homogeneous shells with the properly chosen parameters. Frequencies of the minima of the scattering cross section, which are associated with the cloaking, typically depend on whether TE or TM polarization is considered. In some cases, large-positive-ε and largenegative-e objects can be cloaked. In other cases, non-ideal multifrequency cloaking can be realized. ©2009 Optical Society of America.
Open Access
Spatial filters based on EBG structures with anisotropic-like dispersion
(IEEE, 2010) Serebryannikov, A.E.; Cakmak, A.O.; Çolak, Evrim; Özbay, Ekmel
Bandpass and bandstop spatial filters based on the dielectric-rod EBG structures are proposed and validated for the frequency range from 18 to 25 GHz. The obtained experimental results are well consistent with the theoretical predictions. The exploited mechanism utilizes, in particular, anisotropic-like dispersion, which can occur in the conventional EBG structures made of isotropic materials.
Open Access
Spoof-plasmon relevant one-way collimation and multiplexing at beaming from a slit in metallic grating
(Optical Society of America, 2012) Çakmakyapan, Semih; Serebryannikov, A.E.; Caglayan H.; Özbay, Ekmel
Diode and collimator/multiplexer functions are suggested to be combined in one device that is based on a thin metallic grating with a single subwavelength slit. A proper choice of the structural (a)symmetry of the grating can result in obtaining one-way collimation and multiplexing with a single on-axis or off-axis, or two off-axis narrow outgoing beams. It is possible due to freedom in utilizing different combinations of the excitation conditions of the spoof surface plasmons at the four grating parts - right and left front-side and right and left back-side ones. Such a combining provides one with an efficient tool to engineer one-way collimators and multiplexers with the desired characteristics. Strong asymmetry in transmission with respect to the incidence direction (forward vs backward case) can be obtained within a wide range of variation of the incident beam parameters, i.e., angle of incidence and frequency, while the outgoing radiation is concentrated within a narrow range of the observation angle variation. Most of the observed asymmetric transmission features can be qualitatively explained using the concept of the equivalent source placed inside the slit. © 2012 Optical Society of America.
Open Access
Unidirectional transmission in non-symmetric gratings containing metallic layers
(Optical Society of American (OSA), 2009) Serebryannikov, A.E.; Özbay, Ekmel
The mechanism of achieving unidirectional transmission in the gratings, which only contain isotropic dielectric and metallic layers, is suggested and numerically validated. It is shown that significant transmission in one direction and nearly zero transmission in the opposite direction can be obtained in the same intrinsically isotropic gratings as those studied recently in A. E. Serebryannikov and E. Ozbay, Opt. Express 17, 278 (2009), but at a non-zero angle of incidence. The tilting, non-symmetric features of the grating and the presence of a metallic layer with a small positive real part of the index of refraction are the conditions that are necessary for obtaining the unidirectionality. Single- and multibeam operational regimes are demonstrated. The frequency and angle ranges of the unidirectional transmission can be estimated by using the conventional framework based on isofrequency dispersion contours and construction lines that properly take into account the periodic features of the interfaces, but should then be corrected because of the tunneling arising within the adjacent ranges. After proper optimization, this mechanism is expected to become an alternative to that based on the use of anisotropic materials. © 2009 Optical Society of America.
Open Access
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.