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Now showing items 64-83 of 136

  • 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 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 ...
  • Molecular fluorescence above metallic gratings 

    Andrew, P.; Barnes, William L. (American Physical Society, 2001)
    We present measurements of the fluorescence of emitters located in close proximity (d<λ) to metallic grating surfaces. By measuring both the spontaneous emission lifetime and angle-dependent radiation pattern of a monolayer ...
  • 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. ...
  • On the mechanism of charge transport in pentacene 

    van Laarhoven, Hendrik A.; Flipse, Cees F. J.; Koeberg, Mattijs; Bonn, Mischa; Hendry, Euan; Orlandi, G.; Jurchescu, O. D.; Palstra, T. T. M.; Troisi, A. (American Institute of Physics, 2008)
    Terahertz transient conductivity measurements are performed on pentacene single crystals, which directly demonstrate a strong coupling of charge carriers to low frequency molecular motions with energies centered around 1.1 ...
  • 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 ...
  • Operating characteristics of a semiconducting polymer laser pumped by a microchip laser 

    Turnbull, G. A.; Andrew, P.; Barnes, William L.; Samuel, I. D. W. (American Institute of Physics, 2003)
    We report the demonstration of a compact, all-solid-state polymer laser system featuring a microchip laser as the pump source. The laser was configured as a surface-emitting, two-dimensional distributed feedback laser, ...
  • Optical Control over Surface-Plasmon-Polariton-Assisted THz Transmission through a Slit Aperture 

    Hendry, Euan; Garcia-Vidal, F. J.; Martin-Moreno, L.; Gómez Rivas, J.; Bonn, Mischa; Hibbins, Alastair P.; Lockyear, Matthew J. (American Physical Society, 2008)
    We demonstrate optical control over the transmission of terahertz (THz) radiation through a single subwavelength slit in an otherwise opaque silicon wafer. The addition of periodic corrugation on each side of the wafer ...
  • 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 ...
  • Optical properties of a light-emitting polymer directly patterned by soft lithography 

    Lawrence, J. R.; Andrew, P.; Barnes, William L.; Buck, M.; Turnbull, G. A.; Samuel, I. D. W. (American Institute of Physics, 2002)
    We present the optical properties of a directly patterned light-emitting polymer. The patterned poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-paraphenylenevinylene film is fabricated using hot embossing lithography. The effect ...
  • Optical resonances on sub-wavelength silver lamellar gratings 

    Gadsdon, Martyn Richard; Hooper, Ian R.; Sambles, J. Roy (Optical Society of America, 2008)
    The optical response of sub-wavelength silver lamellar gratings has been theoretically investigated. Two distinct types of resonance have been predicted for incident radiation with E-field perpendicular to the long axis ...
  • Optical waveguide characterization of a tristable antiferroelectric liquid crystal cell 

    Jewell, Sharon A.; Sambles, J. Roy; Goodby, J. W.; Hall, A. W.; Cowling, S. J. (American Institute of Physics, 2004)
    The optical convergent-beam waveguide technique has been used to characterize a homogeneously aligned 3 µm cell containing a liquid crystal in the antiferroelectric phase. The director structure has been quantified with ...
  • Optically guided mode study of nematic liquid crystal alignment on a zero-order grating 

    Hallam, B. T.; Sambles, J. Roy (American Physical Society, 2000)
    The characterization of a liquid crystal cell, which comprises one zero-order (that is, at the wavelength of study it is nondiffractive) diffraction grating and one rubbed polyimide-coated substrate, has been performed ...
  • ORE demo 

    Alastair, Hibbins (Uni of Exeter, 2013-10-04)
    An abstract
  • Orientational transition in a nematic liquid crystal at a patterned surface 

    Atherton, T. J.; Sambles, J. Roy (American Physical Society, 2006)
    We consider a semi-infinite nematic in contact with a periodic patterned surface with alternate planar and homeotropic stripes. Extending the work of Barbero et al., we find the free energy (assuming K1=K3) for the situations ...