Bulletin of the American Physical Society
2007 APS March Meeting
Volume 52, Number 1
Monday–Friday, March 5–9, 2007; Denver, Colorado
Session W38: Focus Session: Negative Index Materials: Concepts to Applications II |
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Sponsoring Units: FIAP Chair: Evgenii Narimanov, Princeton University Room: Colorado Convention Center 501 |
Thursday, March 8, 2007 2:30PM - 3:06PM |
W38.00001: Negative-Index Metamaterials in the Visible Range Invited Speaker: In conventional materials, out of the two field components of light, electric and magnetic, only the electric one (``electric hand'') efficiently couples to and probes the atoms of a material while its ``magnetic hand'' remains almost unused because the interaction of atoms with the magnetic filed component of light is normally very week. Metamaterials, i.e. artificial materials with rationally designed properties, can enable the coupling of\textit{ both} field components of light to meta-atoms, enabling entirely new optical properties and exciting applications with such ``two-handed'' light. Metamaterials are expected to open a gateway to unprecedented electromagnetic properties and functionality unattainable from naturally occurring materials. Negative-refractive index metamaterials create entirely new prospects for guiding light on the nanoscale, some of which may have revolutionary impact on present-day optical technologies. The extraordinary nonlinear optical properties of negative-index metamaterials are also discussed. We review this new emerging field of metamaterials and recent progress in demonstrating a negative refractive index in the optical and visible range, where applications can be particularly important, including sub-wavelength imaging and cloaking objects, i.e. making them invisible. [Preview Abstract] |
Thursday, March 8, 2007 3:06PM - 3:18PM |
W38.00002: Simulations of ferrite-dielectric-wire composite negative index materials Frederic Rachford, Douglas Armstead, Vincent Harris, Carmine Vittoria We have performed extensive finite difference time domain (FDTD) simulations to design ferrite based negative index of refraction (NIM) composites. Our simulations center on the use of Barium M type ferrite with in-plane anisotropy. A wire grid is employed to provide negative permittivity. The ferrite and wire grid interact to provide both \underline {negative} and \underline {positive} index of refraction transmission peaks in the vicinity of the BaM resonance. We find that the wires and the ferrite must be spatially separated by a low loss dielectric (Mylar). The ferrite and dielectric media are modeled as thin lamina with a mono-directional wire grid centered in the dielectric lamina. The ferrite and dielectric lamina are paired with combined thickness equal to the square wire grid lattice distance. We assume the presence of a in plane orienting magnetic field. Working with thin planar oriented ferrite lamina implies that the composites will have a negative index in only one direction of propagation. Notwithstanding the extreme anisotropy in the index of refraction of the composite, negative refraction is seen at the composite air interface allowing the construction of a focusing concave lens with magnetically tunable focal length. [Preview Abstract] |
Thursday, March 8, 2007 3:18PM - 3:30PM |
W38.00003: Superlens with a virtual focus Alexei Efros Recently there has been growing interest in the creation of lenses with a very sharp focus. Those lenses are a). The Veselago lens that is a slab of the material where both $\varepsilon $and $\mu $ are negative and b). The quasistatic lens where only one of those two is negative. Pendry claimed that in the absence of absorption both types of lenses are perfect. It has been shown very soon that the supersolution, proposed by Pendry does not exist for any lens with a real focus. In this presentation I propose a lens with a virtual focus (VF) and show that without absorption this focus is perfect. It happens due to the Pendry amplification of the evanescent waves, but in the case of the VF these arguments do not contradict to any general theorem. The supersolution exists without any absorption. The VF is located either in front of the slab or inside the slab. In fact, there is no maximum of the field in the VF itself, but this focus may be at the point that is very close to the rare interface of the slab, but still inside the slab. Then the field at the interface will have a very narrow maximum. Its width tends to zero as the location of the VF tends to the interface. The effect of small absorption is considered. [Preview Abstract] |
Thursday, March 8, 2007 3:30PM - 3:42PM |
W38.00004: Filtering Components in Optical Nanocircuits Using Plasmonic Metamaterials Nader Engheta, Andrea Alu Following our recently developed concept of lumped nanocircuit elements at optical frequencies, here we apply analytical and numerical techniques to demonstrate that various arrangements of such optical nanoelements may provide relatively complex optical nanocircuits with various filtering functions, such as bandpass filters, in optical domains. These optical nanocircuit units, operating as nanofilters, are sub-wavelength in size and are formed by collecting and arranging plasmonic and non-plasmonic nanostructures in proper orders and topology in a planar geometry. Our study shows how such optical nanocircuits may provide resonant responses, with transfer functions that allow filtering the incoming optical signals at will. The input signal may be coupled into such nanofilters using plasmonic nanoantennas, and the output of such elements may be coupled with another section of the nanocircuit or connected to a nanowaveguide carrying out the signal, mimicking the functionalities of low-frequency filters in RF circuits. We present samples of our theoretical results and discuss related physical insights. Future steps in this work will also be mentioned. [Preview Abstract] |
Thursday, March 8, 2007 3:42PM - 3:54PM |
W38.00005: Experimental Observation and Theory of Optical Magnetism in Dielectrics Samuel Oliveira, Stephen Rand We report the power dependence of extremely intense linear magnetic response to non-relativistic optical fields in water, benzene and carbon tetrachloride at room temperature. Quantitative agreement is obtained with the multipole expansion, showing that transient magnetic dipoles can be as large as half the electric dipole moment under identical conditions at optical frequencies in dielectrics. This discovery will enable optical magnetic resonance and tunable negative index behavior in low-loss media. [Preview Abstract] |
Thursday, March 8, 2007 3:54PM - 4:06PM |
W38.00006: Coupling to nanoscale negative-refraction planar waveguides Robyn Wangberg, Viktor Podolskiy Negative index non-magnetic strongly anisotropic waveguides have been shown to provide efficient beam steering and manipulation in nanoscale areas with applications that include sub-diffraction planar lens imaging and photonic funnels. In this work we study the coupling to and from sub-wavelength planar waveguides of different sizes and compare the transmission through a negative-index structure to the Bethe prediction for positive index materials. We simulate EM wave propagation and imaging in arbitrary waveguide configurations with a focus on designing and optimizing planar-waveguide based beam-steering photonic devices. [Preview Abstract] |
Thursday, March 8, 2007 4:06PM - 4:18PM |
W38.00007: A spectroscopic multi-angle probe of metamaterial permeability Tom Driscoll, Sabarni Palit, Willie Padilla, Tong Ren, Jack Mock, Gregory Andreev, Sang-Yeon Cho, Nan Marie Jokerst, David Smith, Dimitri Basov We present spectroscopic data for acute-angle reflection and transmission of two planar metamaterial samples, one at microwave frequencies and one at far-infrared frequencies. We show that the observed evolution of the magnetic resonance with the increasing angle of incidence is in quantitative agreement with the Fresnel expressions. This finding uncovers a convenient approach towards the retrieval of optical constants of metamaterials by fitting the Fresnel theory to multiple angle-datasets simultaneously; thus obviating the need for phase information. Physically reasonable values for the magnetic permeability are recovered by this no-phase fitting in the case of both the microwave and infrared metamaterials. [Preview Abstract] |
Thursday, March 8, 2007 4:18PM - 4:30PM |
W38.00008: Ensembles of plasmonic nanoparticles at optical frequencies for negative index media A.M. Bratkovsky, E. Ponizovskaya Metamaterials in a form of an array of metallic nanoparticles support collective plasmonic excitations that are believed to be responsible for various unusual phenomena, like surface enhanced Raman scattering (SERS). The array is analogous to a dual structure for a metal film with periodic array of holes, which can provide an extraordinary transmission. We have investigated the electromagnetic response of ordered films of metallic nanoparticles. In particular, we looked at various cubic, close- packed, and columnar structures. This included the nanoparticle realization of G.Eleftheriades' structure that was speculated by N.Engheta et al. to produce negative index medium (NIM). It appears that open- and close-packed arrays behave similarly: there are plasmon resonances and high transmission of certain wavelength that is considerably larger than the separation between the particles, yet {\bf no negative index behavior}, unlike in e.g. ``fishnet'' metal-dielectric heterostructures that are NIM[1]. We discuss a realization of ``transparent metal'' metamaterial with emphasis on ``channeling'' of radiation in columnar structures. [1] W. Wu et al., cond-mat/0610352, to appear in Appl. Phys. A, Special Issue on Negative Index Metamaterials. [Preview Abstract] |
Thursday, March 8, 2007 4:30PM - 4:42PM |
W38.00009: Optical Hyperlens: Far-field imaging beyond the diffraction limit Zubin Jacob, Leonid Alekseyev, Evgenii Narimanov We propose an approach to far-field optical imaging beyond the diffraction limit. The proposed system allows image magnification, is robust with respect to material losses and can be fabricated by adapting existing metamaterial technologies in a cylindrical geometry. This device relies on recently proposed strongly anisotropic metamaterials that feature opposite signs of the two permittivity tensor components, $\varepsilon _{\bot }$ and $\varepsilon _{\vert \vert }$ [1-2]. Such metamaterials have been theoretically shown to support propagating waves with very large wavenumbers (in ordinary dielectrics, such high-$k $modes undergo evanescent decay) [3]. This unusual property arises from the \textit{hyperbolic }functional form of the dispersion relation for such metamaterials, and is the key feature enabling subwavelength resolution of our proposed device. It is for this reason that we call our imaging device \textit{the hyperlens}. [1] V. A. Podolskiy, and E. E. Narimanov, ``Strongly anisotropic waveguide as a nonmagnetic left-handed system,'' Phys. Rev. B \textbf{71}, 201101 (2005). [2] V. A. Podolskiy, L. Alekseyev, and E. E. Narimanov, ``Strongly anisotropic media: the THz perspectives of lefthanded materials'', J. Mod. Opt. \textbf{52}(16) 2343 (2005). [3] A. A. Govyadinov and V. A. Podolskiy, ``Meta-material photonic funnels for sub-diffraction light compression and propagation,'' Phys. Rev. B \textbf{73}(15), 155108 (2006). [Preview Abstract] |
Thursday, March 8, 2007 4:42PM - 4:54PM |
W38.00010: Nanoparticle susceptibilities and the bianisotropic formalism Jeremy Neal, Peter Palffy-Muhoray Since the spatial extent of nanoparticles is not negligible compared to the wavelength of light, non-local effects may be expected in the electric and magnetic response of nanoparticles at optical frequencies. It has been suggested that such spatially non-local response may be taken into account via the bianisotropic formalism for the constitutive equations. We have calculated the susceptibilities of pairs of nanowires as a function of orientation relative to the incident fields using the discrete dipole approximation. We compare the results of our simulations with predictions of the bianisotropic description, and summarize our observations. [Preview Abstract] |
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