Resonant tunneling of light through thin metal films via strongly localized surface plasmons

W.-C. Tan, T. W. Preist, and J. Roy Sambles, Physical Review B, Vol. 62, pp. 11134-11138 (2000). "Copyright © 2000 by the American Physical Society."We present a theoretical model of the optical response of a silver film having narrow-grooved zero-order gratings on both sides. It is found that incident p-polarized photons can resonantly tunnel through such a metal film via exciting standing-wave surface plasmon-polariton (SPP) modes localized in the grooves of the two opposite surfaces. This leads to strong transmission peaks in the visible and ultraviolet regions, while for s-polarized photons the film acts as a nearly perfect mirror

Making Tunnel Barriers (Including Metals) Transparent

Ian R. Hooper, T. W. Preist, and J. Roy Sambles, Physical Review Letters, Vol. 97, article 053902 (2006). "Copyright © 2006 by the American Physical Society."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 "wall." Optical experiments involving beyond-critical-angle-tunnel barriers in the frustrated total internal reflection scheme which mimic quantum mechanical systems provide convincing proof of this remarkable effect. The same mechanism also allows vastly enhanced transmission through unstructured thin metal films without the need for surface wave excitation

Double-period zero-order metal gratings as effective selective absorbers

W.-C. Tan, J. Roy Sambles, and T. W. Preist, Physical Review B, Vol. 61, pp. 13177-13182 (2000). "Copyright © 2000 by the American Physical Society."The electromagnetic response of a zero-order metal grating having a primary deep short-period component and a shallow long-period component is modeled. It is found that such a metal grating has an unusual surface-plasmon-polariton band structure and exhibits strong selective absorption of incident radiation. This opens up potential for designing metal surfaces with specific optical response features

Finite conductance governs the resonance transmission of thin metal slits at microwave frequencies

James R. Suckling, Alastair P. Hibbins, Matthew J. Lockyear, T. W. Preist, J. Roy Sambles, and Christopher R. Lawrence, Physical Review Letters, Vol. 92, article 147401 (2004). "Copyright © 2004 by the American Physical Society."Fabry-Perot–like resonant transmission of microwave radiation through a single subwavelength slit in a thick aluminum plate is quantified for a range of slit widths. Surprisingly, and in contrast to previous studies [e.g., Y. Takakura, Phys. Rev. Lett. 86, 5601 (2001)], the resonant frequency exhibits a maximum as a function of slit width, decreasing as the slit width is reduced to less than 2% of the incident wavelength. This result accords with a new model based on coupled surface plasmon theory taking into account the finite conductivity, and hence permittivity, of the metal. This is contrary to a common assumption that metals can be treated as infinitely conducting in this regime

Surface plasmon-related resonances on deep and asymmetric gold gratings

M. Kreiter, S. Mittler, W. Knoll, and J. Roy Sambles, Physical Review B, Vol. 65, article 125415 (2002). "Copyright © 2002 by the American Physical Society."Based on theoretical calculations, the surface plasmonlike resonances on deep and asymmetric gold gratings are reinvestigated and assigned to two classes possessing different characteristic symmetry properties. Reflectivity measurements on deep grating structures with varying depth and asymmetry allow for a detailed study of the influence of these parameters on the lowest-order resonances as well as the experimental observation of a higher-order resonance

Fluorescent dyes as a probe for the localized field of coupled surface plasmon-related resonances

M. Kreiter, T. Neumann, S. Mittler, W. Knoll, and J. Roy Sambles, Physical Review B, Vol. 64, article 075406 (2001). "Copyright © 2001 by the American Physical Society."The fluorescence light of Cy5 dye molecules in the vicinity of a metal grating is studied for varying directions of both the exciting and the emitted light. A different angular dependence of the intensity of the emitted light is observed for different directions of excitation. Model calculations that take into account the localization of the electrical field of grating-coupled surface plasmon-related resonances are in good agreement with the experimental observations. In addition, the spatially inhomogenous photobleaching of the dye in the field of the coupled resonances is experimentally observed. These results can be viewed both as a way to use chromophores as molecular probes for the localized electrical near field of coupled surface plasmon-related resonances and as a way to manipulate dye molecules on a submicron scale