Now showing items 1-20 of 56

    • 45-GHz bandwidth-efficiency resonant-cavity-enhanced ITO-Schottky photodiodes 

      Biyikli, N.; Kimukin, I.; Aytür, O.; Gökkavas, M.; Ünlü, M. S.; Ozbay, E. (IEEE, 2001)
      High-speed Schottky photodiodes suffer from low efficiency mainly due to the thin absorption layers and the semitransparent Schottky-contact metals. We have designed, fabricated and characterized high-speed and high-efficiency ...
    • All-aluminum hierarchical plasmonic surfaces in the infrared 

      Ayas S.; Bakan, G.; Dana, A. (The Optical Society, 2016)
      All-Aluminum metal-insulator-metal resonator structures withmultiple metal-insulator stacks showing resonances in the mid-infrared(MIR) are fabricated. Ultrathin native Al2O3 is used as the insulator layersenabling simple ...
    • Analysis of double-negative materials with surface integral equations and the multilevel fast multipole algorithm 

      Ergül O.; Gürel, L. (2011)
      We present a fast and accurate analysis of double-negative materials (DNMs) with surface integral equations and the multilevel fast multipole algorithm (MLFMA). DNMs are commonly used as simplified models of metamaterials ...
    • Analysis of nonequilibrium steady-states 

      Yeşil, Ayşe Ferhan (Bilkent University, 2016-12)
      Non-equilibrium is the state of the almost all systems in the universe. Unlike equilibrium systems, they interfere with their surroundings which results in never ceasing uxes. There is no unified theory to understand these ...
    • Atomic and electronic structure of carbon strings 

      Tongay, S.; Dag, S.; Durgun, E.; Senger, R. T.; Ciraci, S. (IOP Publishing Ltd., 2005)
      This paper presents an extensive study of various string and tubular structures formed by carbon atomic chains. Our study is based on first-principles pseudopotential plane wave and finite-temperature ab initio molecular ...
    • Designing materials with desired electromagnetic properties 

      Bulu, I.; Cağlayan, H.; Özbay, E. (Wiley, 2006)
      In this work, we suggest and demonstrate a robust method to tune the plasma frequencies of wire mediums. The method we suggest involves the use of two or more wire arrangements in the unit cell. By incorporating the method ...
    • Directional selectivity through the subwavelength slit in metallic gratings 

      Cakmakyapan, S.; Caglayan, H.; Serebryannikov, A.; Ozbay, E. (2011)
      An approach for obtaining strong directional selectivity through a single subwavelength slit in non-symmetric metallic gratings is shown theoretically and experimentally. Directionality effect originates from the different ...
    • Directivity enhancement and deflection of the beam emitted from a photonic crystal waveguide via defect coupling 

      Guven, K.; Ozbay, E. (Optical Society of American (OSA), 2007)
      We experimentally and numerically investigate the spatial distribution of the emission from a photonic crystal waveguide, coupled with defects, that are located at the output edge. Two defects that are located symmetrically ...
    • Dynamic tuning of plasmon resonance in the visible using graphene 

      Balci, S.; Balci, O.; Kakenov, N.; Atar, F. B.; Kocabas, C. (The Optical Society, 2016)
      We report active electrical tuning of plasmon resonance of silver nanoprisms (Ag NPs) in the visible spectrum. Ag NPs are placed in close proximity to graphene which leads to additional tunable loss for the plasmon resonance. ...
    • EFIE and MFIE, why the difference? 

      Chew W.C.; Davis, C.P.; Warnick, K.F.; Nie, Z.P.; Hu J.; Yan, S.; Gürel, L. (2008)
      EFIE (electric field integral equation) suffers from internal resonance, and the remedy is to use MFIE (magnetic field integral equation) to come up with a CFIE (combined field integral equation) to remove the internal ...
    • Electromagnetic scattering of THz waves from a microsize graphene-sandwiched thin dielectric strip 

      Oguzer, T.; Altintas, A. (IEEE Computer Society, 2018)
      Two-dimensional (2-D) scattering of the H-polarized plane wave by a composite flat material strip is investigated. It is made as graphene-dielectric-graphene sandwich-like structure which is placed in the free space. Our ...
    • Electronic transport through a kink in an electron waveguide 

      Yalabik, M. C. (Institute of Electrical and Electronics Engineers, 1994)
      The current-voltage denendence correspondinp to electronic transport through a kink in an electronic waveguide is analyzed. No phase breaking dissipation mechanisms are considered, but the effects of the Coulomb interaction ...
    • Enhanced transmission of microwave radiation in one-dimensional metallic gratings with subwavelength aperture 

      Akarca-Biyikli, S. S.; Bulu, I.; Ozbay, E. (American Institute of Physics, 2004)
      We report a theoretical and experimental demonstration of enhanced microwave transmission through subwavelength apertures in metallic structures with double-sided gratings. Three different types of aluminum gratings ...
    • Experimental study of linear closed-loop control of subsonic cavity flow 

      Yan P.; Debiasi, M.; Yuan X.; Little J.; Özbay H.; Samimy, M. (2006)
      A study is presented of the modeling and implementation of different concepts for linear feedback control of a single-mode resonance shallow cavity flow. When a physics-based linear model is used for cavity pressure ...
    • Fano effect in a double T-shaped interferometer 

      Moldoveanu, V.; Dinu, I. V.; Tanatar, B. (Springer, 2009)
      We study the coherent transport in a one-dimensional lead with two side-coupled quantum dots using the Keldysh's Green function formalism.The effect of the interdot Coulomb interaction is taken into account by computing ...
    • Fast and accurate analysis of large metamaterial structures using the multilevel fast multipole algorithm 

      Gürel, L.; Ergül, Ö.; Ünal, A.; Malas, T. (2009)
      We report fast and accurate simulations of metamaterial structures constructed with large numbers of unit cells containing split-ring resonators and thin wires. Scattering problems involving various metamaterial walls are ...
    • Ferroelectric based tuneable SRR based metamaterial for microwave applications 

      Ozbay, E.; Aydin, K.; Butun, S.; Kolodziejak, K.; Pawlak, D. (2007)
      We discuss the possibility of achieving tunable split ring resonators at microwave frequencies. One method is to use varying capacitance values to tune the magnetic resonance frequency. As another method ferroelectric thin ...
    • Flexible strain sensors based on electrostatically actuated graphene flakes 

      Fardindoost, S.; Alipour, A.; Mohammadi, S.; Gökyar, S.; Sarvari, R.; Iraji Zad, A.; Demir, H. V. (Institute of Physics Publishing, 2015)
      In this paper we present flexible strain sensors made of graphene flakes fabricated, characterized, and analyzed for the electrical actuation and readout of their mechanical vibratory response in strain-sensing applications. ...
    • Förster resonance energy transfer enhanced color-conversion using colloidal semiconductor quantum dots for solid state lighting 

      Nizamoglu, S.; Demir, H. V. (American Institute of Physics, 2009-10-15)
      In this paper, we present Förster resonance energy transfer (FRET)-enhanced color-conversion using colloidal semiconductor quantum dot nanocrystals (NCs) to make reddish-orange light-emitting diodes for use in ultraefficient ...
    • Harmonic cantilevers for nanomechanical sensing of elastic properties 

      Sahin, O.; Yaralioglu, G.; Grow, R.; Zappe, S. F.; Atalar, Abdullah; Quate, C.; Solgaard, O. (Institute of Electrical and Electronics Engineers Inc., 2003)
      We present a micromachined scanning probe cantilever, in which a specific higher order flexural mode is designed to be resonant at an exact integer multiple of the fundamental resonance frequency. We have demonstrated that ...