Now showing items 41-60 of 115

  • Independently controlling permittivity and diamagnetism in broadband, low-loss, isotropic metamaterials at microwave frequencies 

    Parke, L.; Hooper, Ian R.; Edwards, E.; Cole, N.; Youngs, I.J.; Hibbins, Alastair P.; Sambles, J. Roy (American Institute of Physics (AIP), 2015-03-09)
    A metamaterial based on the design of Shin et al. [Phys. Rev. Lett. 102, 093903 (2009)] that allows independent control of its permeability and permittivity has been fabricated and experimentally characterised. It is ...
  • Leaky-wave exploration of two-stage switch-on in a nematic pi-cell 

    Ruan, Lizhen; Sambles, J. Roy (American Institute of Physics, 2005)
    The two-stage switch-on dynamics of a nematic pi-cell are explored in detail using a convergent beam fully-leaky guided mode technique. The cell shows an initial switch-on with a time scale in the range several ms to tens ...
  • Localized surface-plasmon resonances in periodic nondiffracting metallic nanoparticle and nanohole arrays 

    Parsons, J.; Hendry, Euan; Burrows, Christopher P.; Auguié, Baptiste; Sambles, J. Roy; Barnes, William L. (American Physical Society, 2009)
    We compare the optical response of periodic nondiffracting metallic nanoparticle and nanohole arrays. Experimental data from both structures show a pronounced minimum in their wavelength-dependent transmittance that, through ...
  • Low acoustic transmittance through a holey structure 

    Bell, J.S.; Summers, I.R.; Murray, Alasdair R.J.; Hendry, Euan; Sambles, J. Roy; Hibbins, Alastair P. (American Physical Society, 2012)
    The “acoustic double fishnet” is a structure with holes running from its front to back faces, yet at a characteristic frequency it transmits very little sound. The transmittance of this structure, which is comprised of a ...
  • Low angular-dispersion microwave absorption of a dual-pitch nondiffracting metal bigrating 

    Lockyear, Matthew J.; Hibbins, Alastair P.; Sambles, J. Roy; Lawrence, Christopher R. (American Institute of Physics, 2003)
    The surface plasmon modes supported by a nondiffracting 90° bigrating consisting of three grooves per repeat period with one slightly shallower than the other two are characterized by studying the reflectivity from the ...
  • Low angular-dispersion microwave absorption of a metal dual-period nondiffracting hexagonal grating 

    Lockyear, Matthew J.; Hibbins, Alastair P.; Sambles, J. Roy; Lawrence, Christopher R. (American Institute of Physics, 2005)
    The microwave (11.3<λ0<16.7 mm) reflectivity response of a nondiffracting dual-period hexagonal grating is explored. In three directions at 60° to each other, the aluminum grating has a repeat period of 7.2 mm in which ...
  • Making Tunnel Barriers (Including Metals) Transparent 

    Hooper, Ian R.; Preist, T. W.; Sambles, J. Roy (American Physical Society, 2006)
    The classical "brick wall," which may, according to quantum mechanics, leak via tunneling, is here shown to be completely transparent when appropriate impedance matching media are placed both in front of and behind the ...
  • Metamaterial tunnel barrier gives broad band microwave transmission 

    Butler, Celia A.M.; Hooper, Ian R.; Hibbins, Alastair P.; Sambles, J. Roy (American Institute of Physics, 2011)
    A simple structure comprising a metal mesh, symmetrically surrounded by subwavelength thickness dielectric layers, is shown to give near total microwave transmission over a broad frequency range. The mesh may be considered ...
  • Microwave liquid-crystal variable phase grating 

    Yang, Fuzi; Sambles, J. Roy (American Institute of Physics, 2004)
    A voltage-controlled variable phase grating, at microwave frequencies, is described and its response characterized. It comprises a stack of 71 aluminium strips of 1 mm thickness separated by 75 µm spaces, filled with ...
  • Microwave resonances of ultrathin hexagonally-symmetric microcavity arrays 

    Brown, James R.; Hibbins, Alastair P.; Lawrence, Christopher R.; Lockyear, Matthew J.; Sambles, J. Roy (American Institute of Physics, 2012)
    A metamaterial surface formed by three slot gratings at 60° to each other has two possible high-symmetry arrangements. One forms equilateral triangular metal patches, the other a combination of hexagons and small equilateral ...
  • Microwave response of hole and patch arrays 

    Taylor, Melita C.; Edmunds, James D.; Hendry, Euan; Hibbins, Alastair P.; Sambles, J. Roy (American Physical Society, 2010)
    The electromagnetic response of two-dimensional square arrays of perfectly conducting square patches, and their complementary structures, is modeled utilizing a modal matching technique and employing Babinet’s principle. ...
  • Microwave surface-plasmon-like modes on thin metamaterials 

    Lockyear, Matthew J.; Hibbins, Alastair P.; Sambles, J. Roy (American Physical Society, 2009)
    It has recently been shown that the structured surface of a perfect conductor can support surface-plasmon-like modes [Pendry et al., Science 305, 847 (2004)]. Such structures have a thickness of at least the order of the ...
  • Microwave transmission of a compound metal grating 

    Hibbins, Alastair P.; Hooper, Ian R.; Lockyear, Matthew J.; Sambles, J. Roy (American Physical Society, 2006)
    An array of subwavelength slits in a metallic substrate supports a series of Fabry-Perot-like resonances, where each harmonic results in a transmission peak. Addition of extra slits per period yields a compound grating ...
  • Microwave transmission through a single subwavelength annular aperture in a metal plate 

    Lockyear, Matthew J.; Hibbins, Alastair P.; Sambles, J. Roy; Lawrence, Christopher R. (American Physical Society, 2005)
    The resonant transmission of a small annular aperture, with a diameter much smaller than the radiation wavelength, in a thin metal plate is studied at microwave frequencies. It transpires that such an annular aperture ...
  • Microwave transmissivity of a metamaterial–dielectric stack 

    Butler, Celia A.M.; Parsons, James; Sambles, J. Roy; Hibbins, Alastair P.; Hobson, Peter A. (American Institute of Physics, 2009)
    A metamaterial layer comprising of a conducting square mesh surrounding subwavelength holes has a largely pure imaginary effective refractive index. We explore the microwave transmissivity of a stack of such metamaterial ...
  • Microwaves: thin metal slits and liquid crystals 

    Sambles, J. Roy; Hibbins, Alastair P.; Kelly, Robert J.; Suckling, James R.; Yang, Fuzi (SPIE, 2004)
    Using liquid crystals to control the propagation of microwaves is a potentially interesting technology. By incorporating small amounts of liquid crystal in thin slat metal structures through which the microwaves may ...
  • Observation of backflow in the switch-on dynamics of a hybrid aligned nematic 

    Jewell, Sharon A.; Sambles, J. Roy (American Institute of Physics, 2004)
    The optical convergent-beam technique is used to measure, in 0.3 ms steps, the response of the director in a 4.6-µm-thick ZLI-2293 filled hybrid aligned nematic cell when a 10 kHz, 7 Vrms ac voltage is applied to the cell. ...
  • One-way diffraction grating 

    Lockyear, Matthew J.; Hibbins, Alastair P.; White, Kevin R.; Sambles, J. Roy (American Physical Society, 2006)
    Diffraction gratings are elementary tools for much of optics and spectroscopy. Here, at microwave frequencies, we provide a new perspective on these fundamental structures. A transmission diffraction grating is presented ...
  • Optical determination of flexoelectric coefficients and surface polarization in a hybrid aligned nematic cell 

    Mazzulla, A.; Ciuchi, F.; Sambles, J. Roy (American Physical Society, 2001)
    We present an optical study of the influence of both the flexoelectric effect and surface polarization on a hybrid-aligned nematic cell using the half-leaky guided mode technique. Tilt angle profiles, obtained from fits ...
  • Optical imaging of the effect of in-plane fields on cholesteric liquid crystals 

    Jewell, Sharon A.; Sambles, J. Roy (American Physical Society, 2008)
    The effects of in-plane electric fields on the director structure of cholesteric liquid crystals has been imaged in three dimensions using fluorescence confocal polarizing microscopy. The results show that a liquid crystal ...