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- Front Matter: Volume 7353
- Metamaterials I
- Metamaterials II
- Modelling of Metamaterials
- Plasmonics I
- Plasmonics II
- Subwavelength Imaging
- Metamaterials Fabrication Technologies
- Device Application of Metamaterials
- Poster Session
Front Matter: Volume 7353
Front Matter: Volume 7353
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This PDF file contains the front matter associated with SPIE
Proceedings Volume 7353, including the Title Page, Copyright
information, Table of Contents, and the Conference Committee listing.
Metamaterials I
Spatial dispersion in a wire mesh metamaterial
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The homogeneous and transport properties of a set of metallic fibers was studied. The existence of a plasma
frequency was shown and a precise formula was derived. A homogenized system for finite length ohmic wires
was derived. Some numerical simulations were made to study the influence of disorder.
Low-loss infrared metallo-dielectric metamaterials: theory and applications
Show abstract
Man made artificial materials or metamaterials have attracted in the recent years a huge amount of
interest owing to their potentials applications. Among these, we can cite perfect lens [1], hyper lens
[2], electromagnetic cloak [3-7] and applications in non linear and/or guided optics [9-10]. In this
paper we present and review some applications of infrared metallo- dielectric metamaterials
developed in our group including the design of novel low loss negative index metamaterials, realistic
cloaking in the infrared [7], sensing [8-9] and applications in non linear and/or guided optics [9-10]
The basic physics of each presented application is reviewed and the use of these applications on
functional photonic device is discussed.
Negative and imaginary permittivity in 2D photonic macroporous silicon structures
Show abstract
Mechanisms of the negative and imaginary parts of the permittivity formation in 2D photonic macroporous silicon
structures are investigated. Negative part of permittivity in 2D photonic macroporous silicon structures is determined by
the polaritonic and surface electromagnetic mode formation. One of mechanisms of the imaginary permittivity formation
is the electro-optical effect realized clearly in 2D photonic macroporous silicon structures in the near-IR area (impurity
absorption). We investigated the "out-of-plane" optical absorption of 2D photonic macroporous silicon structures taking
into account the optical mode formation and the electro-optical effect. The reflected electromagnetic waves at grazing
angle of light incidence onto macropore surface change effectively the local surface electric field.
Negative effective permeability of multilayers of ordered arrays of metal-dielectric nanosandwiches
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We present a thorough theoretical study of the optical properties of periodic structures built of silver and silica
nanodisks in a sandwich-like configuration, by means of full electrodynamic calculations using the extended
layer-multiple-scattering method. The strong coupling of the metallic nanoparticles and the resulting plasmon
hybridization lead to collective electric and magnetic resonant modes, which can be tuned by changing the
structural parameters, such as nanoparticle size and lattice constant. We analyze the response of single- and
multi-layer architectures of ordered arrays of such nanosandwiches on a dielectric substrate to externally incident
light and evaluate the corresponding effective permittivity and permeability functions. Our results reveal the
existence of optical magnetism, with a strong negative effective permeability over a tunable spectral range at
near-infrared and visible frequencies. We introduce the complex photonic band structure as a tool in the study
of three-dimensional metamaterials and establish additional criteria for the validity of their effective-medium
description. Our work demonstrates the efficiency of the recently developed extended layer-multiple-scattering
method in the study of metamaterials of composite metal-dielectric particles of arbitrary shape.
Metamaterials II
Metamaterial absorber with wide angular and frequency bandwidth
Show abstract
The absorbers usually employed in everyday applications and the ultimate layouts recently proposed in the literature and
based on unconventional material loading, are usually backed by a metallic plate. The metallic backing plays two main
roles. On one hand, it is used to avoid power transmission on the other side of the absorber. On the other hand, it enables
a boundary condition useful to create a reflected component that, combined with the impinging wave, cancels the
reflection from the screen. In order to avoid a metallic backing, proper resonant structures may be employed. In this
frame, it is possible to make use of metamaterials, that are artificial materials exhibiting properties not readily found in
natural materials.
The aim of the paper is to present a theoretical investigation relating to the design of compact microwave absorbers,
made by a proper combination of two metamaterial slabs. The operation principle of that layout is based on the
anomalous surface resonance, arising at the interface between two slabs, characterized by opposite signed values of the
real parts of permittivities and/or permeabilities. We show that these bi-layers, when excited by an impinging
electromagnetic wave, may support a localized interface resonance, whatever the total thickness of the entire setup is,
for any angle of incidence, and no matter what the nature of the backing on the other side of the structure is. We also
propose a new class of miniaturized inclusions, in order to be employed in practical layouts of innovative microwave
absorbers.
Infrared metamaterials and plasmons engineering
Show abstract
Metamaterials in infrared and optical domain are mainly based on metal-dielectric composite.
Collective excitations also called surface plasmons are thus the main mechanism in infrared
metamaterials structures. Taking profit of the plasmonic interpretation instead of LC circuit
approaches (better suited for microwave experiment) new approaches in understanding and
engineering resonances is possible. In this paper we show numerically and experimentally
how certain metamaterials can open opportunities in the engineering of plasmonic modes at
the nanoscale for application including sensing and SERS (surface enhanced Raman
Spectroscopy).
Propagation and tunneling of electromagnetic waves through uniaxial metamaterials at arbitrary orientations of the optical axis
Show abstract
Boundary electrodynamic problem for a layer of effectively uniaxial absorbing metamaterial (MM) is solved. Proper
inhomogeneous waves in the layer are neither TM (TE), when the optical axis is non-parallel to the incidence plane, nor
purely evanescent. Features of excitation of particular waves with linear amplitude dependence on coordinates in MM
are considered. Effect of small dielectric (magnetic) anisotropy and absorption of MM on imaging properties of the
Veselago-Pendry lens is analyzed. It is shown that presence of a small anisotropy is a limiting factor much stronger than
small losses, and careful account of effective permittivity (permeability) anisotropy for "superlens" devices is required.
Optics of metamaterials based on channeled mirror structures
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A new kind of metamaterials based on hierarchically organized mirror channels with semitransparent
walls, metamirror structures (MMS) is investigated theoretically and experimentally. Unusual optical properties
of MMS like back reflection, negative refraction and some others are close to that exhibited by left-handed
materials though the physical mechanisms are different. Being mechanically solid materials due to relatively
small cell sizes (from one to tens microns), the MMS may have abnormal optical properties in wide wavelength
range. The ray tracing is considered for different MMS geometries and types. It is shown that one reflection 2D
MMS's based on rectangular elementary cells being properly curved possess lens properties and MMS lens
generalized law is derived. Also, the MMS membranes may serve as filters of radiation both in reflection and
transmission.
Modelling of Metamaterials
Analysis of metallic nanostructures via a discontinuous-Galerkin time-domain approach
Kai Stannigel,
Michael König,
Jens Niegemann,
et al.
Show abstract
We apply the three-dimensional Discontinuous-Galerkin Time-Domain method to the investigation of the optical
properties of V-shaped metallic nanostructures on dielectric substrates. In particular, we study in detail the
possibility of controlling the spatiotemporal localization of radiation via chirped pulse excitations. Even for
rather small structures, we find significant deviations from predictions based on quasi-static theory.
Analytical modelling of linear and nonlinear properties of metamaterials based on multipole expansion
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A simple analytical model has been developed within the scopes of the macroscopic Maxwell's equations. In the
framework of this model the dispersion relation for plane waves has been calculated for the case of Cut-Wire (CW) and
Split Ring Resonator (SRR) geometries. The dispersion relation has been compared with rigorous numerical calculations.
A possible way to introduce the electric and magnetic material parameters has been suggested. Validity criteria and
applicability limitations of the developed model are discussed. A new type of nonlinearity specific for the metamaterials
- Multipole Nonlinearity - is identified based on the developed model, wheras the second harmonic generation (SHG)
process is considered in detail
Monte Carlo analysis of local distribution of negative refractive index in nanosphere-doped liquid crystal metamaterial
Show abstract
Khoo et al.1 have introduced the concept of tuning of negative refractive index using nanosphere dispersed
nematic liquid crystal (NDLC). Recently,2, 3 we have discussed anchoring forces as a new control parameter for
negative-positive refraction index tuning in NDLC. In particular, we have calculated3 the phase diagrams in
variables electric field - anchoring force for real and imaginary parts of permittivity and permeability for NDLC
using averaged (global) value of refractive index for the inhhomogeneous system. In current paper we analyze an
influence of anchoring forces and of spatial modulation of electric field on local distribution of negative refraction
index in NDLC. The study constitutes a generalization of homogenous isotropic dielectric layer approximation
used in papers.1 Inhomogeneous molecular order in planar NLC cells is modeled using Monte Carlo simulations
with Lebwohl - Lasher effective hamiltonian and Rapini - Papoular term for anchoring forces.
Magneto-optical response enhancement in 1D and 2D magnetoplasmonic crystals
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The results of experimental observation of magneto-optical Kerr effect (MOKE) enhancement caused by surface
plasmon-polaritons (SPP) excitation in 1D and 2D magnetoplasmonic crystals are presented. One-dimensional
nickel magnetoplasmonic crystals have periodic structure formed by periodic nickel grooves made on nickel
surface. The period of the structure is 320 nm and the depth of the grooves is 50 nm. The second group of the
samples represents itself a 2D self-assembled hexagonally ordered monolayer of polystyrene (PS) microspheres
with diameters from 500 to 760 nm and covered by 100- nm - thick nickel film. MOKE measurements performed
in transversal configuration demonstrate that SPP excitation lead to transversal Kerr effect (TKE) enhancement
resulting as a sharp peak in TKE spectrum.
An all-purpose three-dimensional finite element model for crossed-gratings
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We demonstrate the accuracy of the Finite Element Method (FEM) to characterize an arbitrarily shaped
crossed-grating in a multilayered stack illuminated by an arbitrarily polarized plane wave under oblique
incidence. To our knowledge, this is the first time that 3D diffraction efficiencies are calculated using the
FEM. The method has been validated using classical cases found in the literature. Finally, to illustrate
the independence of our method towards the shape of the diffractive object, we present the global energy
balance resulting of the diffraction of a plane wave by a lossy thin torus crossed-grating.
A genetic algorithm based procedure to retrieve effective parameters of planar metamaterial samples
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In this contribution, we present the employment of a Genetic Algorithm (GA) based procedure to retrieve the effective
permittivity and permeability of planar metamaterial samples. The approach used here is the same of standard
Transmission/Reflection (TR) techniques, consisting in extrapolating the sample properties by inversion of its scattering
coefficients. The proposed procedure makes use of parametric models for describing the inherently dispersive behavior
of the involved materials. This approach eliminates the anomalous behavior of most of the commonly used inversion
techniques, providing a consistent representation of the material in the working frequency range. The transition to bulk
effective parameters is also investigated determining a proper sample thickness assuring the validation of the
homogenization procedure.
Dielectric-metal-dielectric nanotip for SNOM
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Superfocusing of light, far better than the diffraction limit, is of crucial importance for scanning near-field optical
microscopy (SNOM), optical chemical sensing, and nanolithography. For SNOM applications there are two typical
geometries. The first are tapered-fiber metal-coated aperture probes, which are being constantly improved. The other are
tapered metal or metal-coated apertureless tips, which are continuously brought to perfection. We propose a modification
of a metal-coated fiber tip, which has an additional, thin, dielectric coating with refractive index greater than that of air,
what leads to higher field enhancement at the tip. The excitation signal is an internal, radially polarized Laguerre-Gauss
beam. There is no sound theoretical model to describe nanofocusing of plasmons and we limit the scope of investigations
to body-of-revolution finite-difference time-domain (BOR FDTD) simulations using in-house code. We find that with an
increase of the refractive index of nanocladdings the maximum enhancement occurs for increasingly longer wavelengths.
Plasmonics I
Propagation of surface plasmons through planar interface
Show abstract
We analyze the scattering of the surface plasmon incident at a planar interface between two dielectrics. By
using the scattering matrix technique, developed by Oulton et al. [Phys. Rev. B 76, 035408 (2007)], we
calculate the transmission, reflection coefficients and radiative losses for oblique incident angles. We found that
the transmission of a surface wave through a single interface between two dielectrics may be accompanied with
radiation losses of 10-40 per cent of the plasmon energy.
The negative refractive index metamaterials as the aggregate of spherical particles or porous disposed in the different ambient medium
Show abstract
The possibility to achieving the negative refraction by the system of the identical and homogenous spherical
particles or porous implanted in the arbitrary ambient medium has been studied. The effective permeability and effective
permittivity is investigated applying Mie scattering theory and Clausius-Mossotti expressions. It is shown that the
magnetic and electric dipole resonance of the scattering field can not simultaneously occur in such system However, the
simultaneous effective negative permittivity and effective negative permeability could be achieved in non resonance case.
Possible range of the parameters of the particles, the porous and the media is established for the different frequencies of
electromagnetic fields. The existence of the negative refraction for the system with noble metals (gold, silver) as a
substance of the particles or of the surrounded medium is considered.
Plasmonics II
Transmission enhancement of light through a metallic nano-slit with periodic metallic nanostrips
Show abstract
The study of the transmission properties of subwavelength apertures has become a very active area of research in
electromagnetism. It is generally accepted that structuring the input surface of the metal film by periodic corrugations is
very effective in the process of transmission enhancement through single apertures. Here instead of periodic
corrugations, we propose to use periodic nano-strips placed before the input surface of the metal film to enhance the
transmission of light through a nano-slit milled in the film. Influences of the structural parameters of periodic nano-strips
on the transmission enhancement are investigated. The transmission efficiency through a 25nm-width silver nano-slit can
be boosted to be η = 164 when six pairs of nano-strips are placed 50nm distant away from the incident surface of the
silver film at λ0 = 1μm, which is originally η = 7.8 without any strips. This indicates that a large part of the incident light
can be transformed into the localized guided wave with strong intensity, and then more light can flow through the
nano-slit. We emphasize that periodic nano-strips can serve as an efficient receiving antenna to harvest light into the
nano-slit.
Plasmon-induced wavelength-dependent polarization switching in optical metamaterials
Show abstract
Strong linear birefringence and dichroism is observed in optical metamaterial consisting of array of subwavelength
elliptical holes in a silver film. Spectroscopic polarimetic measurements reveal structure's ability to convert linear
polarized light by making it highly elliptical (ellipticity up to 1) and rotating the polarization plane by angles up
to 90°. Refractive index difference for two eigenstates of the structure extracted from experimental data varies
from 0.4 to 1.8 in the visible. Linear birefringence and dichroism effects together result in metamaterial's ability
of separating frequency modes by putting them into different polarization modes.
Subwavelength Imaging
Metal-dielectric superlens with ultra-flat phase of the modulation transfer function
Show abstract
We optimize the silver-dielectric layered flat lens in terms of three criteria:the variance of modulation transfer
function (MTF) phase, the absolute values of the MTF phase, and the variance of this part of the phase spectrum
which corresponds to the propagating waves only. All three characterise limited dependence of MTF on the range
of spatial frequencies.
The structure supports the resonant tunnelling of propagating and evanescent waves at distances of several
wavelengths with a high transmission efficiency. Simulations are performed using the transfer matrix method and
verified with the FDTD one. The resolution expressed with FWHM of the point spread function normalized with
respect to wavelength reaches the value as small as 0.12, for the amplitude transmission of 40% and the thickness
of the multilayer equals to 2.4 micrometers. For structures considered, we identify and explain a phenomenon
that resembles focusing at a finite distance from the back plane.
Focusing of radially polarized light with corrugated silver nanolayer
Show abstract
In this paper we present technical details of a metal nanolens in the form of a free standing silver film with no hole on the
optical axis and double-sided concentric corrugations. In a numerical experiment we analyze the nanolens performance,
that is transmission and focusing of radially polarized beams of different full widths at half maximum and wavelengths
from the visible range. Corrugations of the front surface couple incident light to surface plasmons and those on the back
surface allow efficient reradiation. The silver lens of thickness 100 nm has five concentric corrugations of periodicity
500 nm with groove depth and width equal 40 nm and 100 nm, respectively. Focusing properties of such a structure are
analyzed and optimized for wavelengths in the range from 400 to 600 nm. At intensity transmission of 10-25% of
incident light achievable focal spot areas reach down to 0.15λ2. For different illumination parameters the nanolens has
focal lengths from 1 to 2 wavelengths. Without contribution of evanescent waves it focuses a far-field source into a farfield
spot. The nanolens acts like a refractive optical system of high numerical aperture close to unity. Nanolenses of this
kind can be used as light couplers in nanooptics.
Subwavelength focusing using radiationless inteference at optical wavelengths
Show abstract
In this work, I propose two methods for extending radiationless intereference to achieve an extreme subwavelength focus
in the visible part of the optical spectrum. These methods are based on metal-insulator-metal (MIM) waveguide
structures. The first uses the transverse evanescent field from a slit-coupled MIM waveguide. The second uses the
highest order mode of a MIM waveguide array. Subwavelength focusing to a tenth of the optical wavelength is
demonstrated numerically. Considering recent experiments, the proposed structures are practically viable. Methods to
overcome other technical issues associated with this proposal are discussed.
Metamaterials Fabrication Technologies
Proximity-effect induced limitations on the density of electron-beam patterned planar photonic nanostructures
Show abstract
Patterning of deeply subwavelength artificial nanomaterials (photonic crystals, plasmonic metamaterials) for the
visible or near-infrared optical spectrum is a challenging task. Electron-beam lithography is often the method
of choice thanks to its combination of flexibility, accuracy and availability in many research laboratories. We
present an analytical model for large and dense arrays of photonic nanostructures which allows to predict the
maximum fill ratio (radius divided by nearest neighbor distance) before the onset of resist shrinkage between
the individual elements. The model includes geometrical parameters of the design (lattice constant, lattice
symmetry), resist properties (resist contrast) and proximity parameters (beam broadening, backscatter range,
backscatter efficiency). It is shown that the resist contrast has a significant impact on the achievable maximum
fill ratio even for large nearest neighbor distances and that the beam broadening, i.e. the quality of the EBL
equipment, is of paramount importance. The background energy level which is determined by the backscatter
efficiency and the lattice symmetry is shown to have a weaker influence on the maximum fill ratio. The derived
model can be used as a guideline in the project planning stage to predict achievable fill ratios at a planned lattice
constant and consequently an assessment whether a desired functionality at a certain wavelength is possible.
Optical spectroscopy of terbium-scandium-aluminium garnet and terbium-scandium perovskite
Show abstract
Tb3Sc2Al3O12-TbScO3 eutectic crystallizes in a rodlike microstructure, and its potential to exhibit photonic
bandgap has been presented tentatively. In order to model its optical properties there is a need for precise
determination of the optical properties of its component materials in a wide spectral range. Spectroscopic data
in the range from 0.6 to 6.5 eV (190-2100 nm) were obtained using spectroscopic ellipsometer UVISEL, Horiba
Jobin-Yvon. The measurement was completed with mid infrared reflection data using Bruker FTIR spectrometer
in the spectral range from 7500 to 550 cm-1. Optical functions were obtained using fitting of the data with
model dielectric function fulfilling the Kramers-Kronig dispersion relations. Obtained optical functions enable
to model the optical properties of self-organized eutectic micro- and nanostructures.
Design of miniaturized printed monopole antennas through phase-compensation
Show abstract
In this paper, the guidelines for the design of compact transmission-line (TL) metamaterial inspired monopole antennas
are presented. The main difference between the proposed setup and the ones already present in the literature, based on
phase-compensation phenomena enabled by TL-metamaterials, is that the present structure can be realized in fully planar
technology. This peculiar feature allows minimizing the non-idealities introduced by vias and parallel plate capacitors
used in conventional setups, which need to be soldered on the board. On the other hand, the proposed radiating devices
are characterized by relatively low production costs, due to their planar configuration. The operation principles of the
proposed radiators are detailed in the paper, giving the reader the necessary information to perform the design. Some
examples are finally presented and tested through proper full-wave simulations performed with CST Studio Suite 2009.
Device Application of Metamaterials
A quasi-quantitative demonstration of multi-mode refractive index sensors based on standing-wave plasmonic resonances in split ring resonators
Show abstract
We propose a multi-mode refractive index sensor based on split ring resonators (SRRs). By applying thin dielectric layer
with varied refractive index on top of planar SRRs, we clarify the relationship among sensitivity, resonant modes and the
size of SRRs based on standing-wave plasmonic resonances model. Significant peak shifts are observed in FTIR
measurement spectrums, consisting with the simulation results which suggest impressive sensitivities closer to SPR or
LSPR for different resonant modes. Next, the corresponding detection lengths of each mode were examined by varying
the thickness of the overlaid dielectric layer. Lower modes include 1||, 2⊥ and 3|| show thickness saturation effect within
500 nm while higher modes such as 5||, 6⊥ and 7|| present longer detection length at micron scale, which namely, no
saturation effect is observed when the thickness of dielectric layer increased to 2 um. This valuable merit enables the
analysis of activation-dependent cellular interactions that other label-free techniques like surface plasmon resonance
(SPR) are incapable of. In conclusion, the distinct sensing behavior including sensitivity and detection length of the multi
resonant modes in SRRs was investigated, showing SRR-based sensors promise a real-time, operation frequency flexible
and multi-mode solution for biological and chemical detection.
Poster Session
Imaging in the visible wavelength range through anisotropic layered flat lens operating in the canalization regime
Show abstract
We investigate the tunneling of visible light through silver-dielectric superlenses working in the canalization
regime. These structures feature high transmission and a sub-wavelength point spread function. They may
serve as a novel element for mode coupling between ordinary waveguides, photonic crystal waveguides and
plasmonic waveguides. We discuss the accuracy limits of homogenisation originally used in the definition of the
canalisation regime. For this purpose we determine the actual anisotropic effective material parameters of the
stack and compare them to those predicted by the effective medium theory. Further we optimise the structure
with respect to the rigorously calculated transmission properties, rather than using the effective medium theory.
Our analysis is based on the transfer matrix method formulated for multilayers with complex and uniaxially
anisotropic permittivity and permeability tensors. The method does not assume the quasi-static approximation,
retains validity for evanescent waves, and allows for including losses and dispersion into calculations.
Zero-average index band-gap edges in m-bonacci metamaterial multilayers
Show abstract
We examine quasiperiodic multilayers arranged according to m-bonacci sequences that combine ordinary positive index materials and dispersive metamaterials with negative index in certain frequency ranges. When the averaged refractive index, in volume, of the multilayer equals zero, the structure does not propagate light waves and exhibits a forbidden band. In this contribution we recognize some approximated analytical expressions for the determination of the upper and lower limits of the above mentioned zero-average refractive index band gap.
Complex Fourier factorization method applied in modeling optical metamaterials based on 2D periodic nanostructures
Show abstract
The rigorous coupled wave theory dealing with optics of discontinuous two-dimensional (2D) periodic structures
is reformulated by using the complex Fourier factorization method, which is a generalized implementation of the
fast Fourier factorization rules. The modified approach yields considerably improved convergence properties, as
shown on three samples of 2D gratingsmade as periodically arranged cylindrical holes on the top of quartz, silicon,
and gold substrates. The method can also be applied to the calculation of 2D photonic band-gap structures or
nonperiodic cylindrical devices, and can be generalized to elements with arbitrary cross-sections.