Now showing items 1-20 of 23

    • AC-driven, color-and brightness-tunable organic light-emitting diodes constructed from an electron only device 

      Zhao, Y.; Chen, R.; Gao, Y.; Leck, K.S.; Yang X.; Liu, S.; Abiyasa, A.P.; Divayana, Y.; Mutlugun, E.; Tan, S.T.; Sun H.; Demir, H. V.; Sun X.W. (2013)
      In this paper, a color- and brightness-tunable organic light-emitting diode (OLED) is reported. This OLED was realized by inserting a charge generation layer into an electron only device to form an n-i-p-i-n structure. It ...
    • Chiral metamaterials with negative refractive index based on four "U" split ring resonators 

      Li, Z.; Zhao, R.; Koschny, T.; Kafesaki, M.; Alici, K. B.; Colak, E.; Caglayan, H.; Ozbay, E.; Soukoulis, C. M. (American Institute of Physics, 2010-08-23)
      A uniaxial chiral metamaterial is constructed by double-layered four "U" split ring resonators mutually twisted by 90°. It shows a giant optical activity and circular dichroism. The retrieval results reveal that a negative ...
    • Computational analysis of complicated metamaterial structures using MLFMA and nested preconditioners 

      Ergul Ö.; Malas, T.; Yavuz Ç.; Ünal, A.; Gürel, L. (2007)
      We consider accurate solution of scattering problems involving complicated metamaterial (MM) structures consisting of thin wires and split-ring resonators. The scattering problems are formulated by the electric-field ...
    • Database research at Bilkent University 

      Ulusoy, Ö. (ACM, 2005)
      The research activities of the Database Research Group of Bilkent University are discussed. The research is mainly focused on the topics of multimedia databases, Web databases, and mobile computing. The Ottoman Archive ...
    • Development of micro-structured metamaterials for innovative antenna layouts 

      Bilotti F.; Capolino F.; Gonzalo, R.; Ozbay, E.; Romeu J.; Schuchinsky, A.; Tretyakov, S.; Vardaxoglou, Y. (2007)
      In this paper, we present the joint activities developed in the frame of the FP6 European Network of Excellence METAMORPHOSE in the field of new micro-structured materials for antenna applications. One of the key scientific ...
    • Distance laboratory applications ERRL: A study on radio communication in electronic field 

      Aydin, C. Ç.; Türkmen, G.; Özyurt, E.; Aydm, E. U.; Çaǧiltay, N. E.; Özbek, M. E.; Alparslan, N. C.; Kara, A. (2008)
      In the last decade, the effect of internet usage in education is gradually increased. When we look from academic perspective, the new technologies provided alternatives for students learning. As distance education becomes ...
    • An efficient non-Lambertian organic light-emitting diode using imprinted submicron-size zinc oxide pillar arrays 

      Liu, S. W.; Wang, J. X.; Divayana, Y.; Dev, K.; Tan S.T.; Demir, H. V.; Sun, X. W. (AIP, 2013)
      We report phosphorescent organic light-emitting diodes with a substantially improved light outcoupling efficiency and a wider angular distribution through applying a layer of zinc oxide periodic nanopillar arrays by pattern ...
    • Experimental observation of cavity formation in composite metamaterials 

      Caglayan H.; Bulu I.; Loncar, M.; Ozbay, E. (Optical Society of American (OSA), 2008)
      In this paper, we investigated one of the promising applications of left-handed metamaterials: composite metamaterial based cavities. Four different cavity structures operating in the microwave regime were constructed, and ...
    • Flexible metamaterials for wireless strain sensing 

      Melik, R.; Unal, E.; Perkgoz, N. K.; Puttlitz, C.; Demir, H. V. (American Institute of Physics, 2009-11-04)
      We proposed and demonstrated flexible metamaterial-based wireless strain sensors that include arrays of split ring resonators (SRRs) to telemetrically measure strain. For these metamaterial sensors, we showed that a flexible ...
    • The magical world of metamaterials 

      Ozbay, E. (2009)
      In recent years, there has been a burgeoning interest in rapidly growing field of metamaterials due to their unprecedented properties unattainable from ordinary materials. Veselago pointed out that a material exhibiting ...
    • The magical world of metamaterials 

      Caglayan H.; Ozbay, E. (2009)
      We review experimental and theoretical studies performed on left-handed metamaterials (LHM). The metamaterials exhibit quiet unusual electromagnetic properties such as negative refraction, negative phase velocity, subwavelength ...
    • Metamaterial based cloaking with sparse distribution of spiral resonators 

      Guven, K.; Saenz, E.; Gonzalo, R.; Ozbay, E.; Tretyakov, S. (2010)
      We investigate the application of a metamaterial that is formed by the sparse distribution of spiral resonators as an optical transformation medium is in order to achieve electromagnetic cloaking. The well-known Clausius-Mossotti ...
    • Metamaterial based telemetric strain sensing in different materials 

      Melik, R.; Unal, E.; Perkgoz, N.K.; Puttlitz, C.; Demir, H. V. (Optical Society of American (OSA), 2010)
      We present telemetric sensing of surface strains on different industrial materials using split-ring-resonator based metamaterials. For wireless strain sensing, we utilize metamaterial array architectures for high sensitivity ...
    • Metamaterial-based wireless RF-MEMS strain sensors 

      Melik, R.; Unal, E.; Perkgoz, N.K.; Puttlitz, C.; Demir, H. V. (2010)
      Approximately 10% of the fractures do not heal properly because of the inability to monitor fracture healing. Standard radiography is not capable of discriminating whether bone healing is occurring normally or aberrantly. ...
    • Millimeter-wave scale metamaterials 

      Alici, K.B.; Ozbay, E. (2009)
      We review two metamaterial configurations, which are operating at the millimeter-wave scale, in terms of design, fabrication, and characterization. We observed both numerically and experimentally at around 100 GHz a narrow ...
    • Miniaturization and characterization of metamaterial resonant particles 

      Aznar F.; Bonache J.; Martín F.; Ozbay, E.; Alici, K. B.; Bilotti, F.; Tricarico, S.; Vegni, L.; Baena J.D.; Jelinek L.; Marqués, R. (2008)
      This paper is focussed on the miniaturization and characterization of semi-lumped resonators, of interest for the synthesis of metamaterial-based structures such as metamaterial transmission lines, frequency selective ...
    • Negative phase advance in polarization independent, multi-layer negative-index metamaterials 

      Aydin, K.; Zhaofeng L.; Sahin L.; Ozbay, E. (Optical Society of American (OSA), 2008)
      We demonstrate a polarization independent negative-index metamaterial (NIM) at microwave frequencies. Transmission measurements and simulations predict a left-handed transmission band with negative permittivity and negative ...
    • Negative refraction and focusing by a left-handed material slab in free space 

      Aydin, K.; Ozbay, E. (2006)
      Negative refraction and focusing by a left-handed metamaterial (LHM) slab are experimentally verified. We measured refractive index of slab as -1.86. The flat lens behavior of LHM is demonstrated for two different point ...
    • Negative refraction and subwavelength focusing using left-handed composite metamaterials 

      Ozbay, E.; Aydin, K. (2008)
      We review experimental studies performed on left-handed metamaterials (LHM) at microwave frequencies. The metamaterial structure is composed of periodic arrays of split-ring resonators and wire meshes and exhibits a ...
    • Nested metamaterials for wireless strain sensing 

      Melik, R.; Unal, E.; Perkgoz, N. K.; Santoni, B.; Kamstock, D.; Puttlitz, C.; Demir, H. V. (IEEE, 2009-12-28)
      We designed, fabricated, and characterized metamaterial-based RF-microelectromechanical system (RF-MEMS) strain sensors that incorporate multiple split ring resonators (SRRs) in a compact nested architecture to measure ...