Bulletin of the American Physical Society
2005 APS March Meeting
Monday–Friday, March 21–25, 2005; Los Angeles, CA
Session V39: Metamaterials for Negative Refraction and Related Phenomena |
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Sponsoring Units: DCMP Chair: David R. Smith Room: LACC 514 |
Thursday, March 24, 2005 11:15AM - 11:27AM |
V39.00001: On the excitation of surface plasmon polariton in homogeneous left-handed materials Rabia Moussa, Costas Soukoulis Results of the excitation of the surface plasmon polariton (SPP) in homogeneous left-handed materials (LHM) are presented. The role of the evanescent waves in exciting and enhancing the transmission is examined. It is demonstrated that, within the attenuated total internal reflection geometry as well as with a line source, the evanescent waves excite the SPPs at the Air/LHM interface. The negative medium amplifies their magnitude and consequently enhances their transmission. The SPP's are excited in the first interface and facilitate the energy transfer to the second interface. Once the steady state time is reached, only the SPP's at the second interface are excited assuring an amplification of the evanescent waves inside the medium. As expected a system with n= -1 at the matching condition focuses the image in better way compared to other cases when the ratio between the permeability and the permittivity of the material differs from 1. Therefore, the image is restored with the evanescent modes as well as with the propagating modes. The case of photonic crystals is also examined. [Preview Abstract] |
Thursday, March 24, 2005 11:27AM - 11:39AM |
V39.00002: Measurements of cross polarization in negative index metamaterials John Derov, Beverly Turchinetz, Everett Crisman, Alvin Drehman, Steven Best The most usual form of left handed or negative refractive index metamaterial employs planar metallic resonant structures to produce simultaneously negative electric permittivity and magnetic permeability in a microwave frequency band. These structures are similar to planar twist polarizers, which can be used to produce signal rotation and circular polarization. Because it is not possible to measure cross polarization in the guided wave chambers which are widely used with negative index metamaterials, polarization rotation has not been previously investigated. We have now performed free space measurements in an anechoic chamber and characterized the effects of negative index metamaterials on signal rotation. We have measured up to 25 degrees of polarization rotation through a negative index prism of 4 cm average thickness. We have found that polarization conversion is a significant loss mechanism which has been neglected. We also consider the importance of symmetry and prism angle geometry on this conversion loss. [Preview Abstract] |
Thursday, March 24, 2005 11:39AM - 11:51AM |
V39.00003: Experimental characterization of magnetic surface plasmons on Jonah Gollub, David Smith, David Vier, Tim Perram, Jack Mock, David Schurig We examine the surface plasmons (SPs) that exist at the interface between air and a metamaterial constructed of split ring resonators(SRRs). The SRR metamaterial possesses a frequency band in the microwave regime (12.5 - 14 GHz) over which the permeability is negative. We apply an attenuated total reflection technique in the Otto configuration (OATR) to excite and probe the surface plasmons. A beam of microwaves is reflected from a higher dielectric (Polycarbonate) prism. Resulting evanescent microwave fields on the transmission side of the prism couple to SPs on the metamaterial and are indicated by a dip in the reflected power. The experimental data is compared with analytic solutions in which the metamaterial slab is approximated as an infinite half-space. The frequency-dependent permeability (and permittivity) of the SRRs is derived from finite-element simulations on an SRR structure with the same parameters as that measured. [Preview Abstract] |
Thursday, March 24, 2005 11:51AM - 12:03PM |
V39.00004: Criteria for a Brewster angle in negative-index materials C.J. Fu, P.N. First, Z.M. Zhang The demonstration of negative-index materials (NIMs) has resulted in a surge of interest in the study of reflection and refraction at the interfaces of NIMs. The Brewster angle can exist in both TE and TM waves for scattering upon an NIM. We present criteria for the existence of a Brewster angle for polarized plane waves incident between arbitrary lossless media. The results are summarized in a regime map, based on the permittivity and permeability of the two media. The well-known result for normal dielectrics (refracted wave perpendicular to reflected) is shown to be a special case which has a counterpart for incidence on an NIM: The refracted wave is perpendicular to the incident wave at the Brewster angle when $\varepsilon _{1}$ = -$\varepsilon _{2}$ or $\mu _{1}=-\mu _{2}$. The Ewald-Oseen extinction theorem is applied as an aid to understanding the results. This work may be a useful supplement to the understanding of the material's electromagnetic behavior. [Preview Abstract] |
Thursday, March 24, 2005 12:03PM - 12:15PM |
V39.00005: Negative refraction and superlens behavior in a two-dimensional photonic crystal Lei Zhang, Rabia Moussa, S. Foteinopoulou, G. Tuttle, K. Guven, E. Ozbay, Costas Soukoulis We experimentally and theoretically studied a new left-handed (LH) structure based on a photonic crystal (PC) with a negative refractive index. The structure consists of triangular array of rectangular dielectric bars with dielectric constant 9.61. Experimental and theoretical results demonstrate the negative refraction and the superlensing phenomena in the microwave regime. The results show high transmission for our structure for a wide range of incident angles. Furthermore, surface termination within a specific cut of the structure excite surface waves at the interface between air and PC and allow the reconstruction of evanescent waves for a better focus and better transmission. The normalized average field intensity calculated in both the source and image planes shows almost the same full width at half maximum for the source and the focused beam. [Preview Abstract] |
Thursday, March 24, 2005 12:15PM - 12:27PM |
V39.00006: Fabrication and Optical Measurements of Nanoscale Meta-Materials: Terahertz and Beyond Zhao Hao, Michael C. Martin, Alex Liddle, Erik H. Anderson, Willie J. Padilla, David Schurig, David R. Smith We report on our efforts to simulate and fabricate micro- and nano-scale meta-materials, and experimentally measure negative magnetic permeability and electric susceptibility in such structures. We make use of the nano-fabrication technology and expertise of Lawrence Berkeley National Lab's Center for X-Ray Optics (CXRO) for fabricating potential left-handed meta-materials. We begin by verifying micron-scale split-ring-resonator structures which have magnetic resonances at terahertz (THz) frequencies, following reference [1]. Our structures, however, are fabricated on extremely thin ($\sim$20 nm) SiN films, making the resonators close to free-standing. We then scale the structures to sub-micron dimensions to bring the resonance frequencies higher. We will present simulations and experimental results on these nano-scale structures. \\ $[1]$ T. J. Yen, W. J. Padilla, N. Fang, D. C. Vier, D. R. Smith, J. B. Pendry, D. N. Basov, X. Zhang, Science, 303, 1494-1496 (2004). [Preview Abstract] |
Thursday, March 24, 2005 12:27PM - 12:39PM |
V39.00007: Negative index lens aberrations David Schurig, David R. Smith We examine the Seidel aberrations of thin spherical lenses composed of media with refractive index not restricted to be positive. We find that consideration of this expanded parameter space allows for the reduction or elimination of more aberrations than is possible with only positive index media. In particular, we find that spherical lenses possessing real aplanatic focal points are possible only with a negative index. We perform ray tracing, using a custom code that relies only on Maxwell’s equations and conservation of energy, that confirms the results of the aberration calculations. This research was supported by DARPA (Contract No. MDA972-01-2- 0016) and a Multiple University Research Initiative (MURI), sponsored by ONR (Contract No. N00014-01-1-0803). [Preview Abstract] |
Thursday, March 24, 2005 12:39PM - 12:51PM |
V39.00008: Microwave Transmission Through A Superconducting Metamaterial Michael Ricci, Nathan Orloff, Steven Anlage An important new prediction for negative index of refraction materials is that of evanescent wave amplification under the ideal condition of n = -1 + $i$ 0 precisely, in the absence of retardation effects. This property will permit, in principle, image reconstruction with arbitrary precision and detail. Current metamaterial designs suffer from high losses due to metallic and dielectric dissipation of the elements. We employ a metamaterial design with superconducting and low-loss dielectric materials to reduce these losses. In addition, we observe qualitatively new behavior of the metamaterial arising from the unique electrodynamic properties of superconductors. We present data on a wire medium, a loop medium, and a combination of the two. Novel features not seen at room temperature are manifest in the superconducting state. For example, we can examine the properties of a single loop as a function of temperature and measure its tunability due to the kinetic inductance variation. The prospect of observing evanescent wave amplification is discussed. This work is supported by the National Science Foundation through grant NSF/ECS-0322844. [Preview Abstract] |
Thursday, March 24, 2005 12:51PM - 1:03PM |
V39.00009: Anomalous refractive effects at the interface of two-dimensional photonic crystals Costas M. Soukoulis, Stavroula Foteinopoulou Photonic crystals (PCs) can enable left-handed (backwards wave) propagation when certain conditions are met [1]. Nonetheless, negative refraction at PC interfaces is neither a prerequisite nor a manifestation of backwards wave propagation [2]. We study systematically the refractive behavior of two-dimensional PCs with the Finite Difference Time Domain (FDTD) method [3]. We have identified four distinct cases for which a negatively refracted beam is present. We analyze the different mechanisms that can lead to a negatively refracted beam with the wave vector diagram formalism. We found that such formalism is general, and always leads to a correct prediction/interpretation of the refracted beam(s). On the other hand, the Bragg rule, although widely used, can be applied only to specific cases that involve an interface of a two- or three- dimensional photonic crystal. [1] S. Foteinopoulou, E. N. Economou, and C. M. Soukoulis, Phys. Rev. Lett. 90, 107402 (2003). [2] S. Foteinopoulou and C. M. Soukoulis, Phys. Rev. B 67, 235107 (2003). [3] S. Foteinopoulou and C. M. Soukoulis, cond-mat/0403542. [Preview Abstract] |
Thursday, March 24, 2005 1:03PM - 1:15PM |
V39.00010: Negative Group Delays without Distortion in an Electronic Filter Ron Henderson, Jeremy Munday A negative group velocity occurs for an electromagnetic signal when the group refractive index of the medium, $N_{g}$, is less than zero. The group velocity, described as $v_{g}$ = ($c$/$N_{g})$, can be faster than $c$ or even negative when $N_{g}<$1. All experimental reports of this phenomenon have involved media for which the group velocity was frequency dependent, i.e. $v_{g}=v_{g}$(\textit{$\omega $}). As a result, signals are necessarily distorted because different frequency components travel with different velocities. An interesting circumstance would occur in a medium if the group velocity was negative and \textit{constant }over a certain range of frequencies. Any signal containing only frequency components within this range could experience a negative group velocity, yet not be distorted in the process. The group \textit{velocity} in optics has an analogous effect in electronic circuits called the group \textit{delay}. We present observations of constant negative group delays for electronic signals using a specially tailored amplifier design. The design allows a wide range of frequencies to experience a constant group delay, resulting in negatively delayed signals, without distortion. [Preview Abstract] |
Thursday, March 24, 2005 1:15PM - 1:27PM |
V39.00011: Nanocircuit Elements, Left-Handed Nano-Transmission-Lines and Layered Metamaterials at Optical Frequencies Nader Engheta, Andrea Alu, Alessandro Salandrino It is known that for certain noble metals such as Ag, Au, the optical wave interaction with such metallic nanostructures involves surface plasmonic resonances. We present theories for synthesizing nanocircuit elements in the optical domain using such plasmonic and non-plasmonic nanoparticles. Three basic circuit elements, i.e., nano-inductors, nano-capacitors, and nano-resistors, are envisioned in terms of small nanostructures with different material properties. Coupled nanocircuits and parallel and series combinations are also discussed, which may provide road maps for the synthesis of more complex nanocircuits in the IR and visible bands. When these nanoparticles are arranged to form series nano-capacitors and shunt nano-inductors, a left-handed nano-transmission line may be resulted in which guided waves possess negative refractive index at optical frequencies. Such structures may be envisioned as plasmonic and non-plasmonic thin layers, exhibiting forward and backward-wave propagation properties in the optical domain and offering a mechanism for sub-wavelength- resolution, beyond-diffraction-limit imaging that can lead to potentials for nanoscale lithography and high-capacity data storage. [Preview Abstract] |
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V39.00012: Imaging Potential of a Negative Refractive Index Lens Kevin Webb, Ming-Chuan Yang, David Ward, Keith Nelson Negative refractive index or left-handed (LH) material has been proposed as a perfect lens, whereby evanescent fields in a lossless LH slab would be amplified. Negative permittivity and permeability imply frequency dispersion and, through the Kramers-Kronig relations, loss. Expressing the fields in the object plane by plane wave expansion and assuming some degree of loss in the LH slab, the transfer function of the imaging system for each plane wave component can be obtained. We show that even minute loss has a drastic impact on the support of the plane wave transfer function. This means that for a realistic low-loss LH slab, achieving high resolution implies a near-field restriction, which in turn dictates the slab thickness. An imaging example considers a one-wavelength-thick LH slab, and an incident sub-wavelength transverse magnetic field which is a pulse in space. An approximate image forms in the center of the slab and at the image plane. In addition, the Poynting vector plot of the imaging system shows vortices forming at the surfaces of the LH material as well as at the image plane. [Preview Abstract] |
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V39.00013: Negative refraction in the polariton regime: an illustration of a nonlinear process in negative refractive materials David Ward, Keith Nelson, Kevin Webb A phonon-polariton is an admixture of light waves and lattice vibrations which can be generated through impulsive stimulated Raman scattering$\--$a nonlinear interaction between near and far-infrared radiation. Characteristic to the polariton regime is polariton dispersion, in which an avoided crossing between electromagnetic and vibrational degrees of freedom result in two branches for the dispersion relation seperated by a bandgap. Through finite-difference-time-domain (FDTD) simulations, we illustrate a third branch that occurs in the bandgap when a magnetic resonance is introduced that overlaps with the existing ionic resonance. We demonstrate the consequences of this new branch on Cerenkov-like terahertz radiation generated through difference frequency mixing and ISRS. [Preview Abstract] |
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V39.00014: THz spectroscopy and ellipsometry of magnetic metamaterials Willie Padilla, Ta Jen Yen, Nicholas Fang, David Vier, David R. Smith, John Pendry, Xiang Zhang, Dimitri Basov We present S and P polarized measurements of artificial bianisotropic magnetic metamaterials, (metallic split rings), with resonant behavior at infrared frequencies. Simulation of the reflectance yields excellent agreement with the experimental data. It is shown that although the artificial magnetic materials do indeed exhibit a magnetic response, care must be taken to avoid an undesirable electric dipole resonance, due to lack of reflection symmetry in one orientation. The effects of bianisotropy on negative index are detailed and shown to be beneficial for certain configurations of the material parameters. [Preview Abstract] |
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