Bulletin of the American Physical Society
2007 APS March Meeting
Volume 52, Number 1
Monday–Friday, March 5–9, 2007; Denver, Colorado
Session V44: Focus Session: Plasmons in Nanoholes, Arrays and Structured Surfaces |
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Sponsoring Units: DMP Chair: Fernando Reboredo, Oak Ridge National Laboratory Room: Colorado Convention Center 507 |
Thursday, March 8, 2007 11:15AM - 11:27AM |
V44.00001: Nonlinear Optical Effects in Periodic Arrays of Nanoholes in Metallic Films Xiwen Wang, Stephen Gray, George Schatz Extraordinary optical transmission (EOT) by periodic subwavelength apertures in metallic films has been much studied. Recent studies have shown that different aperture shapes can give quite different transmission spectra. For circular holes, EOT is often attributed to coupling with surface plasmons. Rectangular holes, however, can show more enhanced EOT and localized modes inside the holes, as opposed to plasmons, are often the dominant features. This implies that in the process of resonant transmission, light is highly concentrated inside the holes, which opens the possibility for exploring nonlinear effects. We use the finite-difference time-domain calculations to study the transmission properties of metallic films with arrays of rectangular subwavelength holes, each hole filled with a Kerr nonlinear material. We consider both the perfect metal limit and silver that supports plasmons. We analyze the transmission spectra as a function of incident intensity. Due to the large electric fields associated with the localized modes inside the holes, moderate incoming fluxes can result in dramatic changes in the positions of the transmission peaks. [Preview Abstract] |
Thursday, March 8, 2007 11:27AM - 11:39AM |
V44.00002: Theoretical Study of Optical Transmission Enhancement through Sub-Wavelength Apertures: Determining the Role of Surface Plasmon Polaritons Philip Flammer, James Martineau, Reuben Collins, Ian Schick, Michael Horowitz, Russell Hollingsworth Enhanced optical transmission (EOT) through sub-wavelength apertures in metal films has been observed from both experimental and theoretical studies of circular apertures surrounded by bulls-eye groove configurations or simpler linear apertures flanked by grooves. These studies have also generated much debate over the driving mechanisms involved. In this talk, theoretical results from a commercial finite element PDE solver will be presented with supporting experimental results for linear aperture/groove structures. This study confirms the integral role of surface plasmon polaritons in causing EOT, and also shows the importance of surface cavity resonances. Results will be presented exploring the role of the geometry of the grating structures, and how to tune the EOT resonance wavelength by changing the aperture/groove geometry. This material is based on work supported by the National Science Foundation under Grant No. DMI-052228. [Preview Abstract] |
Thursday, March 8, 2007 11:39AM - 11:51AM |
V44.00003: The coupling of surface plasmons in periodic arrays of subwavelength holes Ruwen Peng, Zhaohui Tang, Zhan Wang, Yongjun Bao, Mu Wang We demonstrate here that transmission optical enhancement originates not only from surface plasmons(SPs) but also from the coupling of SPs on the silver film perforated with a periodic array of subwavelength holes. We fabricate the structured silver films by coating the film with magnetron sputtering, and then drilling holes with focused-ion-beam facility. The optical measurements are in good agreement with numerical calculations based on the full-vectorial three-dimensional finite-difference time-domain method. The peaks in measured transmission spectrum have also been analytically indexed by using effective-dielectric-constant model. It is shown that the coupling of SPs leads to blue shift of transmission peaks, and increases with decreasing the thickness of silver films. We suggest that these properties open an unique way to tune electromagnetic wave in subwavelength optics. [Preview Abstract] |
Thursday, March 8, 2007 11:51AM - 12:03PM |
V44.00004: Plasmonic properties of a nanosized hole in a thin metallic film Tae-Ho Park, Peter Nordlander We investigate the optical properties of a nanosize hole in a thin metallic film. We show that the optical absorption spectrum is characterized by a plasmon resonance of an energy that depends strongly on the ratio of the hole diameter and the film thickness in qualitative agreement with experimental results. Microscopically, the nanohole plasmon is shown to consist of a collective state formed by propagating thin film plasmons. The hole surface exposes the film plasmons and introduce a dipole moment which allows the coupling to incident light. We also show that the energy of the hole plasmon resonance depends strongly on the polarization and direction of the incident light. [Preview Abstract] |
Thursday, March 8, 2007 12:03PM - 12:15PM |
V44.00005: Interaction between surface plasmon and 2-dimensional nano-defects at metallic surfaces. Raul Garcia-Llamas, Jorge Gaspar-Armenta, Judith Tánori-Cordova, Manuel Leyva-Lucero A theoretical study of light diffraction and intensity of near field from two-dimensional nano-defects at metallic surface illuminated with electromagnetic plane waves is presented. Results for one or two Gaussian-shaped sub-wavelength defects at silver surface are shown. The light diffraction patterns shown minima at specific angular directions in the case of two defects separated a distance $a_{x}$. These minima are associated to the ration (\textit{$\lambda $}/2$a_{x})$ and depend on the localization of the defects, being \textit{$\lambda $} the wavelength of the illumination light. The Near-Field intensity, calculated to constant height, shown oscillations associated to the excitation of surface plasmon, which amplitude are grater for smaller width of the Gaussian defect. [Preview Abstract] |
Thursday, March 8, 2007 12:15PM - 12:27PM |
V44.00006: Mapping of the optical emission in the vicinity of the surface of a subwavelength aperture flanked by periodic grooves in a gold film Ian C. Schick, James T. Martineau, Reuben T. Collins, P. David Flammer, Russell E. Hollingsworth Enhanced optical transmission through subwavelength apertures surrounded by periodic features has been a subject of great recent interest. Equally important are the emission characteristics of these structures. Transmission enhancement has typically been observed as peaks in the spectral dependence of transmission measured in the far-field. Here we use near-field scanning optical microscopy to spatially map the optical emission in the vicinity of the aperture and as emission propagates into the far field. We show the dependence of the emission pattern on the wavelength of the incidence in addition to structural parameters, such as spacing between the grooved regions and the aperture and the spatial period of the grooves. We observe that the emission pattern is governed by interference effects between emission from the aperture and scattered light from adjacent surface features. This material is based on work supported by the National Science Foundation under Grant No. DMI-0522281. [Preview Abstract] |
Thursday, March 8, 2007 12:27PM - 12:39PM |
V44.00007: Dependence of Transmission Through Subwavelength Linear Apertures on Grating/Aperture Separation Michael Hurowitz, Ian Schick, Philip Flammer, James Martineau, Russell Hollingsworth, Reuben Collins Far-field transmission spectra were obtained for structures consisting of subwavelength linear apertures flanked on one or both sides by periodic grating arrays in Au films. In each set of structures, the distance from the grating arrays to the aperture was incrementally varied. Transmission spectra clearly showed enhancement and suppression relative to an isolated aperture. A systematic shift in these extremes was observed with varying cavity width while holding other structural parameters constant. Distinct bands of enhancement and suppression arise from this analysis, consistent with a predictive analytical model. Our conclusions allow for precise control over enhancement/suppression at specific wavelengths in future structures. [Preview Abstract] |
Thursday, March 8, 2007 12:39PM - 12:51PM |
V44.00008: Lensless focusing and optical trapping Christopher DuFort, Bogdan Dragnea Force mapping of optical gradients associated with electromagnetic fields above subwavelength apertures in a gold thin film has been studied using scanning probe techniques. Vertical cross-sections of this resulting field demonstrate that, in certain conditions, the light emerges in the form of a tightly focused beam even when the incident beam is only weakly focused. Quantification of the near-field in the vicinity of these apertures has shown it is possible to deflect a free particle resulting in an optical trapping effect. Applications involving lensless focusing below the diffraction limit and comparisons with traditional optical tweezing are discussed. [Preview Abstract] |
Thursday, March 8, 2007 12:51PM - 1:03PM |
V44.00009: Effective Non-Localities of Nano-Layered Meta-Materials Justin Elser, Viktor Podolskiy, Ildar Salakhutdinov, Ivan Avrutsky Multi-layered nano-composites have been suggested for negative index of refraction systems, photonic funnels, super- and hyper-lenses, as well as other nanophotonic structures. We analyze the electromagnetic modes in such systems and show that they are not described by conventional effective-medium theories. We demonstrate the response of a majority of realistic layered structures is strongly affected by effective non-localities. We develop the analytical description of the relevant phenomena and confirm our results with rigorous numerical solutions of the Maxwell equations. Finally, we demonstrate that multi-layered plasmonic nanostructures support high-index volume modes confined to deep subwavelength areas by using the formalism we have developed. [Preview Abstract] |
Thursday, March 8, 2007 1:03PM - 1:15PM |
V44.00010: Fluorescence enhancement from silver nanostructures. Shyhauh Guo, Hung-Chih Kan, Ray Phaneuf We report on experimental investigations of the fluorescence enhancement by nanotextured silver structures and its dependence on the incident light polarization and on the lateral periodicity. We find strong enhancement for TM mode polarization at smaller periods for thin spacer layers. Thicker spacer layers instead produce strong TE mode enhancement at small spacings. [Preview Abstract] |
Thursday, March 8, 2007 1:15PM - 1:27PM |
V44.00011: Influence of Local Field and Particle Plasmon on Fluorescence Enhancement from Spherical Nano-silver Particles Shu-Ju Tsai, Hung-Chih Kan, Shy-Hauh Guo, De-Hao Tsai, Michael Zachariah, Ray Phaneuf We report on investigation of fluorescence enhancement from silver nano-particles with selected diameters ranging from 50 nm to 320 nm. We measure the fluorescent intensity for two fluorophores, Cy3 and Cy5, coated on silver nano-particles deposited on silicon substrate using excitation source of an Ar ion laser at 514 nm and a HeNe laser at 633nm, respectively. We find that the optimum diameter shifts to a larger value for the larger wavelength fluorophore; this is consistent with the particle plasmon- resonance dependence on particle size. However, we find that while the fluorescence enhancement drops sharply for larger particle sizes the extinction coefficient doesn't. To understand this inconsistency, we perform numerical calculation with the discrete dipole approximation (DDA) method to calculate the extinction coefficient and the electric field strength near a single Ag particle on Si substrate. In comparison with measurement, the local field strength near the particle shows a size dependence in qualitative agreement with the fluorescence; the extinction coefficient does not. [Preview Abstract] |
Thursday, March 8, 2007 1:27PM - 1:39PM |
V44.00012: Ultra-long range surface plasmon modes Charles G. Durfee, Reuben T. Collins, Thomas E. Furtak, Russell E. Hollingsworth It is well known that the propagation length of surface plasmon waves can be extended by exciting the appropriate mode of an isolated noble metal layer. The losses, however, increase substantially as the refractive index of the surrounding medium increases. Using a transfer matrix calculation, we have discovered that a thin, low-index dielectric adjacent to the metal layer can increase the intrinsic propagation length arbitrarily as the bound mode approaches cutoff. This geometry can be implemented in structures that combine metal-oxide-semiconductor (MOS) fabrication with plasmonic waveguides. [Preview Abstract] |
Thursday, March 8, 2007 1:39PM - 1:51PM |
V44.00013: Suppression of transmission minima and maxima with structured metal surface Yongyuan Zhu, Qianjin Wang, Chengping Huang, Jiaqi Li Extraordinary optical transmission through perforated metal films has received much attention recently. In this paper, we propose a method for studying the transmission properties, in which the Fourier coefficient of reciprocal lattice vectors is manipulated. Especially, due to a zero Fourier coefficient, the suppression of transmission minima and maxima has been experimentally observed. The results open a new way to tailor the transmission properties of light. [Preview Abstract] |
Thursday, March 8, 2007 1:51PM - 2:03PM |
V44.00014: Enhanced Optical Transmission with Coaxial Apertures Michael Haftel, Carl Schlockermann, Shannon Orbons, Ann Roberts, David Jamieson, Darren Freeman, Barry Luther-Davies Recently it has been shown that ``cylindrical'' surface plasmons (CSP's) on cylindrical interfaces of coaxial ring apertures produce a new form of extraordinary optical transmission (EOT) that extends to ever increasing wavelengths as the dielectric ring narrows.\footnote{F. I. Baida et al., Phys. Rev. B \textbf{67,} 155314 (2003); M.I Haftel et al., Appl. Phys. Lett. \textbf{88}, 193104 (2006).} Using analytic and FDTD calculations we present some of the consequences of CSP's on EOT as well as experimental confirmation of such effects. We find that EOT, even with cylindrical apertures, is aided by the increase in cutoff wavelength due to CSP's, which is a consequence of the mode structure of individual apertures. CSP effects also explain most of the long-wavelength features of transmission spectra measured for CR apertures. We also show that CSP's can be ``spoofed'' at low frequencies by coaxial apertures in metamaterials consisting of a (macroscopic) periodic dielectric structure embedded in a perfect conductor. [Preview Abstract] |
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