Browsing by Subject "Dielectric rods"

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    One and two dimensional LiNbO3 photonic crystals
    (IEEE, 2013) Şimşek, Şevket; Mamedov, Amirullah M.; Özbay, Ekmel
    In this report, we present an investigation of the optical properties and band structure calculations for the photonic crystal structures (PCs) based on one-dimensional (1D) and two-dimensional (2D) ferroelectric LiNbO3 crystal. Here we use 1D and 2D periodic crystal structure of dielectric rods and layers in air background. We have theoretically calculated photonic band structure and optical properties of 1D and 2D LiNbO3 PCs. Beside, we have calculated affect PBG properties of different parameters such as filling fraction and the shape. In order to get photonic gap map, we have calculated the gaps as a function of radius of the rods. We have also investigated the nature of guided modes in line defect waveguide. In our simulation, we employed the finite-difference time domain (FDTD) technique which implies the solution of Maxwell equations with centered finite-difference expressions for the space and time derivatives. © 2013 IEEE.
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    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.
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    Wide-angle reflection-mode spatial filtering and splitting with photonic crystal gratings and single-layer rod gratings
    (Optical Society of American (OSA), 2014) Serebryannikov, A. E.; Lalanne, P.; Petrov, A. Y.; Özbay, Ekmel
    New diffractive optical elements offering a frequency tolerant, very efficient, high-pass and bandpass spatial filtering over a broad range of incidence angles are demonstrated by numerical simulations. The device operates in reflection mode owing to the (nearly) perfect blazing. It relies on two-dimensional square-lattice photonic crystals composed of dielectric rods with simple corrugations at the interface. Similar performance can be obtained with gratings composed of a single rod layer placed in the near field of a metal mirror, indicating a route to geometries that can be easily fabricated with modern nanotechnologies. Also equal splitting between zero and first negative orders can be obtained for incidence-angle variations that are wider than 60°. © 2014 Optical Society of America