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- Front Matter: Volume 7754
- Metamaterials: Nonlinear and Active
- Hyperbolic and 'Near-Zero' Metamaterials
- Loss and Gain in Metamaterials
- Plasmonic Materials
- Metamaterials: Fundamentals and Novel Trends
- Chiral Metamaterials
- Transmission, Propagation, and Localization
- Meta-Atoms and Their Interactions
- Focusing and Imaging with Metamaterials
- Negative: Index, Permittivity, and Refraction
- Transformation Optics and Cloaking
- Poster Session
Front Matter: Volume 7754
Front Matter: Volume 7754
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This PDF file contains the front matter associated with SPIE Proceedings Volume 7754, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
Metamaterials: Nonlinear and Active
Active plasmonic and metamaterials and devices
Show abstract
This communication focuses on the integration of organic nonlinear optical and gain materials into plasmonic and
metamaterial device architectures and most specifically focuses on the integration of organic electro-optic (OEO)
materials into such structures. The central focus is on structures that lead to sub-optical wavelength concentration of
light (mode confinement) and the interaction of photonic and plasmonic modes. Optical loss and bandwidth limitations
are serious issues with such structures and optical loss is evaluated for prototype device architectures associated with the
use of silver and gold nanoparticles and membranes supporting plasmonic resonances. Electro-optic activity in organic
materials requires that chromophores exhibit finite noncentrosymmetric organization. Because of material conductivity
and integration issues, plasmonic and metamaterial device architectures are more challenging than conventional triple
stack all-organic device architectures and electro-optic of a given OEO material may be an order of magnitude less in
such structures. Because of this, we have turned to a variety of materials processing options for such integration
including crystal growth, sequential synthesis/self assembly, and electric field poling of materials deposited from
solution or by vapor deposition. Recent demonstration of integration of silicon photonic modulator and lithium niobate
modulator structures with metallic plasmonic structures represent a severe challenge for organic electro-optic material
plasmonic devices as these devices afford high bandwidth operation and attractive VμL performance. Optical loss
remains a challenge for all structures.
Strongly nonlinear wave control in gyroelectric metamaterials
Show abstract
A fascinating review of nonlinear waves in metamaterials is presented. The usual weakly nonlinear approximation is
dispensed with, and there is an emphasis upon complex waveguides. Many opportunities exist for elegant control using
the deployment of magnetooptic environments.
Tunable metamaterial binary nano-particle dispersed liquid crystal cells
Show abstract
Metamaterials with tunable properties are of great importance due to potential applications in super-resolution lensing
and sensors. In this paper we study the feasibility of the fabrication of a metamaterial using binary nanoparticle-dispersed
liquid crystal cell (NDLCC). Depending on the angle between the director axis of the LCC and the incident
beam, types, radii, and volume filling fractions of the nanoparticles, a negative index of refraction cell is obtained in a
certain range of frequencies. The effective index of refraction is calculated using the effective medium theory. The
scattering, extinction, and absorption of such a NDLCC cell is also found. Finally, the influence of the various
parameters to obtain such a negative index metamaterial has been investigated.
Hyperbolic and 'Near-Zero' Metamaterials
Strong spatial dispersion in nanostructured multilayered metal-dielectric optical metamaterials
Show abstract
Periodic layered metal-dielectric nanostructures are used in subwavelength imaging, invisibility cloaking, nano-lithography
and optical nanocircuitry. These optical metamaterials are usually described by local effective
medium model if their periods are much smaller than a wavelength. Our studies show that even under such
strict conditions the metamaterials are nonlocal and exhibit strong spatial dispersion effects. The uniaxial media
support two or more extraordinary waves in certain directions while the local effective model predicts only one.
The strong spatial dispersion is caused by surface plasmon polariton modes at the interfaces between metal and
dielectric layers.A
Multilayer near-IR metallo-dielectric zero index metamaterials with matched impedance
Show abstract
In this study, we report multilayer metallo-dielectric stacks that simultaneously possess a zero refractive index and an
impedance match to free space in the near-IR. A genetic algorithm (GA) was used to optimize the screen geometries and
dimensions of the zero index metamaterials (ZIMs) that consisted of alternating gold (Au) and polyimide films.
Examples of three- and nine-layer ZIMs are shown. The fabrication procedure and characterization methods of the
multilayer metallo-dielectric ZIMs are also described.
Loss and Gain in Metamaterials
Harnessing the electromagnetic absorptions of metamaterials for positive applications
Show abstract
Absorption or loss is inevitable for the metal-based metamaterials (MMs) due to the intrinsic loss of the metal, and
constitutes a major hurdle to the practical realization of most applications such as a sub-wavelength lens. Thus, to reduce
the losses becomes one of the major challenges in the MM field. However, the inevitable loss can also be harnessed to
take a positive role in the applications of MMs such as stealth technology or other types of cloaking devices. In this
presentation, after a brief review of the advances in MMs-based absorbers, we present several schemes to fulfill the
desired electromagnetic absorption properties, both linear and nonlinear. For linear absorption, we have experimentally
demonstrated that the absorption performance of an ordinary microwave absorbing material can be evidently improved
by using the electric resonance resulting from an array of subwavelength metallic circuit elements. For nonlinear
absorption, we show theoretically that the active linear magnetic permeability induces a nonlinear absorption, similar to
the two-photon absorption (TPA), of electric field in a lossy MM with a Kerr-type nonlinear polarization.
Semiconductor plasmonic metamaterials for near-infrared and telecommunication wavelength
Show abstract
Plasmonic materials have conventionally been gold and silver in optical frequencies. However, these conventional
metals in the near-infrared (NIR) and visible spectral ranges suffer from problems such as large losses. With
the advent of metamaterials, these metals pose a serious bottle-neck in the performances of metamaterial-based
devices not only due to the large losses associated with them in the NIR and visible wavelengths, but also their
magnitudes of real permittivity are too large. Both of these problems could be solved by using semiconductors
as plasmonic materials. Heavily doped zinc oxide and indium oxide can exhibit losses that are nearly four times
smaller than silver at the telecommunication wavelength with small negative real permittivity. In this paper, we
present the development of a low loss semiconductor plasmonic material, aluminum doped zinc oxide (AZO).
Plasmonic Materials
Meta-acousto-optics: the interaction of light and sound in an acoustic negative index medium
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In acousto-optics (AO), light is diffracted by traveling ultrasound into upshifted or downshifted orders depending on
their respective propagation vectors. In conventional AO (CAO), the acoustic group velocity has the same direction as
the phase velocity, and hence, the acoustic propagation vector. However, in an acoustic metamaterial, the group velocity
can be positive while the phase velocity is negative. The interaction between light and sound wave-vectors are different
for meta AO (MAO), implying a new interpretation for upshifted and downshifted interactions in MAO. We provide a
heuristic treatment and outline the theory for detailed analysis of interaction between light and pulsed and focused
ultrasound in acoustic metamaterials.
Metamaterials: Fundamentals and Novel Trends
Physical restrictions on the Casimir force between metal-dielectric metamaterials
Mário G. Silveirinha
Show abstract
In this work, we theoretically demonstrate that within the scope of effective medium theory the Casimir interaction
between two arbitrary metal-dielectric metamaterial slabs is attractive at all distances.
On the nanoscale transmission of quantum angular momentum
Show abstract
The electromagnetic propagation of angular momentum associated with photon spin has evolved into a subject of much
broader remit, following the theoretical and experimental realization of optical beams that can convey quantized orbital
angular momentum. The possibility of transmitting such information over nanoscale distances raises numerous issues.
For example, it is known that electron spin can be relayed by near-field communication between exciton states in
quantum dot assemblies; the question arises, can orbital angular momentum be conveyed in a similar way? There are
fundamentally important technicalities surrounding such a prospect, representing potentially serious constraints on the
viability of angular momentum transfer between electronically distinct components in structured nanomaterials. To
resolve these issues it is necessary to interrogate the detailed form of near-field electromagnetic coupling of the relevant
transition multipoles. The emerging results exhibit novel connections between angular momentum content in the near-field.
The analysis leads to a conclusion that there are specific limitations on the nanoscale transmission of quantum
angular momentum, with challenging implications for quantum optical data transmission.
1D current driven metamaterial homogenization
Show abstract
We describe a simple metamaterial homogenization procedure that calculates a limited set of constitutive parameters
that are functions of both the frequency and the wavenumber. This procedure is based on replacing
the inclusions of the metamaterial with current sheets excited by the local electromagnetic fields.
Chiral Metamaterials
Chiral metamaterials reduce the attractive Casimir force
Show abstract
In our previous work [R. Zhao, J. Zhou, Th. Koschny, E. N. Economou, and C. M. Soukoulis, Phys. Rev. Lett. 103,
103602 (2009)], we demonstrated theoretically that one can obtain repulsive Casimir forces and stable nanolevitations
by using chiral metamaterials if the chirality is strong enough. In our recent work [R. Zhao, Th. Koschny, E.N.
Economou, and C.M. Soukoulis, Phys. Rev. B 81, 235126 (2010)], we checked some chiral metamaterial designs and
found that the artificial chiral metamaterials constructed by passive materials is very difficult to reach the critical
chirality to realize repulsive Casimir force. Therefore, in this paper, we give a four-folded rotated Ω-particle chiral
metamaterial as an example, use the effective medium approximation to retrieval the constitutive parameters, and take
the same procedure as we did before to see how much the chiral metamaterial can reduce the attractive force. It shows
that this un-optimized chiral metamaterial can reduce the Casimir attraction by 70%.
Transmission, Propagation, and Localization
Experimental demonstration of slowing light by oscillatory mode in left-handed waveguides
Show abstract
Slowing light has arisen increasing attentions due to its applications
for optical switching, optical hard disk and memories. Among several systems to
potentially demonstrate the slowing light effect, such as electromagnetic induced
transparency (EIT), metamaterial analogue EIT, left-handed waveguides, foremost is
the three-layered left-handed waveguides (LHWG). Therefore, by using a negative
refraction index medium (NRIM) operated at multiple-angle incidences to construct
an LHWG, herein we experimentally demonstrate the effect of slowing light by
activating the oscillatory mode at certain frequency. Our results confirmed by
introducing E-field (or H-field) distribution and power flow recording in CST
simulation software.
Slowing down the light by using coupled stereoscopic dielectric metamaterials
Show abstract
New designs "meta-atom" and "meta-material" composed from all-dielectric resonators with high Q and low loss, this
kind metamaterial is coupled from propagating plane wave and generates electromagnetic response like
electromagnetically induced transparency in atomic vapor. The "meta-atom" or "meta-molecular" are not only workable
in room temperature but also enable three dimensional ommidirectionally incident with superposition stacking.
Meanwhile, the EIT-like via dielectric metamaterial with high transmittance, dramatic index change and tunable
operating frequency. The simulation result agrees the possibility electromagnetically induced transparency -like bulk
exists from microwave to THz region.
Light transport in 2D photonic glasses
Show abstract
The propagation of light in a 2D random medium is studied. The medium is made on dielectric scatterers with a high
permittivity allowing for the existence of Mie resonances. It is shown that, according to the polarization, it is possible to
obtain conduction bands around the resonances.verligh
Gain in negative-index metamaterials and slow-light waveguides
Show abstract
We investigate on the basis of a full three-dimensional spatio-temporal Maxwell-Bloch approach the possibility of
complete loss compensation in non-bianisotropic negative refractive index (NRI) metamaterials. We show that a
judicious incorporation of optically pumped gain materials, such as laser dyes, into a double-fishnet metamaterial
can enable gain in the regime where the real part n′ of the resulting effective refractive index (n = n′ + in″) is
negative. It is demonstrated that a frequency band exists for realistic opto-geometric and material (gain/loss)
parameters where n′ < 0 and simultaneously n″ < 0 hold, resulting in a figure-of-merit that diverges at two
distinct frequency points. Having ensured on the microscopic, meta-molecular level that realistic levels of losses
and even gain are accessible in the considered optical frequency regime we explore the possibility of compensating
propagation losses in a negative refractive index slow-light metamaterial heterostructure. The heterostructure
is composed of a negative refractive index core-layer bounded symmetrically by two thin active cladding layers
providing evanescent gain to the propagating slow light pulses. It is shown that backward-propagating light -
having anti-parallel phase and group velocities and experiencing a negative effective refractive index - can be
amplified inside this slow-light waveguide structure. Our results provide a direct and unambiguous proof that
full compensation of losses and attainment of gain are possible on the microscopic as well as the macroscopic
level in the regime where the non-bianisotropic refractive index is negative - including, in particular, the regime
where the guided light propagates slowly.
Propagation of a Gaussian beam through a stack of positive and negative refractive index materials
Show abstract
Propagation of a monochromatic Gaussian beam through a stack of alternating layers of positive-refractive-index
dielectrics and negative-refractive-index metamaterials is analyzed using paraxial ray-optics approach.
Expressions for the change of the spot-size of the Gaussian beam are derived. Sensors for measuring parameters
that affect the thickness or refractive index of the metamaterials can be developed based on the change of the
spot-size.
Antenna-assisted enhanced transmission through subwavelength nanoholes
Show abstract
By structural engineering of sub-wavelength apertures, we numerically demonstrate that transmission through
apertures can be significantly enhanced. Based on equivalent circuit theory analysis, structured apertures are
obtained with a 1900-fold transmission enhancement factor. We show that the enhancement is due to the
excitation of the strong localized resonant modes of the structured apertures.
Optical Anderson localization in one-dimension: a non-Monte Carlo approach for continuous disorder
Show abstract
A long product of random transfer matrices is frequently used to model disordered one-dimensional photonic bandgap
structures in order to investigate optical Anderson localization. The Lyapunov exponent of this long matrix product,
known to exist from Furstenberg's theorem, is identified as the localization factor (inverse localization length). It is not
unusual to have 5,000,000 random matrices with Monte Carlo chosen elements in one product to calculate a single
Lyapunov exponent, and then have results averaged over as many as 10,000 ensembles. The entire process has to be
repeated for 100 or more frequencies to clearly show the frequency dependence of the optical localization effects. This
paper instead uses a non-Monte Carlo numerical technique to calculate the Lyapunov exponents. This technique, by
Froyland and Aihara, is especially suited to the case where the disorder in the photonic bandgap structure is discrete.
Namely, it is used to calculate the probability distribution of the direction of the vector propagated by the long chain of
random matrices by finding the left eigenvector of a certain sparse row-stochastic matrix. This distribution is used in
Furstenberg's integral formula to calculate the Lyapunov exponent. Now this technique is extended to the case where the
random elements of the photonic bandgap transfer matrices are intended to be chosen from a continuous distribution.
Specifically, discrete probability mass functions whose moments increasingly match those of a uniform probability
density function are used with the Froyland-Aihara method. A very significant savings in computation time is noted
compared to Monte Carlo approaches.
Meta-Atoms and Their Interactions
Depth and extent of gold nanorod photothermal conversion in tissue-like phantoms that contain hemoglobin
Show abstract
Gold nanorods (AuNRs) are of interest for many biomedical applications due to their tunable optical properties. AuNRs
efficiently absorb light in the near-infrared (NIR) region, which induces effects such as hyperthermia and/or cell killing
by localized microbubble formation through photothermal conversion. Our objective was to study the potential of
AuNRs to elicit photothermal conversion effects due to pulsed laser exposure at depth within tissue-like phantoms. The
approach was to measure photothermal conversion in inclusion-containing phantoms representative of breast cancer.
Tissue-like phantoms were prepared with hemoglobin at 10 μM in a homogeneous mixture of 1% agarose and 1%
Intralipid to mimic the optical properties of human breast tissue. Polyethylene glycol AuNR-loaded gel spheres (at an
equivalent optical density of 0.67 at 800 nm) were prepared with hemoglobin at 20 μM in a homogeneous mixture of 1%
agarose and 1% Intralipid. The spherical gel inclusions were cast into the phantom material at a depth of 0, 5, 10, or 15
mm. Phantoms were then exposed to nanosecond pulsed-NIR light (800 nm; 5 ns pulse duration; 17-100 mJ/cm2; 10-
1000 pulse count). Each phantom was then cut longitudinally and imaged with a NIR camera. The images were
examined with image analysis software. Preliminary results indicated that the greatest extent of photothermal conversion
occurred in spherical AuNR-loaded gels next to the phantom surface. Based on these results, we concluded that within
ANSI limits of laser exposure photothermal therapy with AuNR-based agents will be limited to surface lesions and/or
lesions accessible with needle-based light delivery.
Focusing and Imaging with Metamaterials
Optimal parameters of metallic nanorods arrays for subwavelength imaging
Show abstract
The arrays of silver nanorods are known as prospective structures for near-field transmission. However, the
available geometries are operating with incoherent sources and do not properly image the coherent ones. In this
paper it is demonstrated how the geometry proposed in [Phys. Rev. Lett. 95, 267407 (2005)] can be modified
to enable subwavelength imaging of arbitrary coherent sources. The greatly improved performance of the device
is demonstrated numerically both through analysis of transmission and reflection coefficients and by full-wave
simulation of a particular source imaging.
Super-lensing effect of TiO2 NFSL in the mid IR regime
Show abstract
Recently, the near-field superlens (NFSL) has been used as a suitable material for the super-resolution beyond the
diffraction limits. These NFSL materials in the nature, such as metals and polar dielectric crystals, usually have intrinsic
absorption loss in the Re(ε) < 0 region. In the imaging system, such absorption loss decreases the retardation effects by
softening the singularity of transmission resonances, but it does not remove the phase singularity that severely
deteriorates the ideal image restoration. Because of this problem, TiO2 thin film cannot still have sufficient band of
spatial frequency for the super-resolution in the mid IR regime. In this research, we report the achievement super-resolution
in TiO2 NFSL by elimination of the phase singularity based on the phase correction method.
Tunable subwavelength focusing with slit-groove-based metamaterials in THz
Show abstract
We design the THz lens made of slit-groove-based metamaterials with tunable far-field focal length as well as
subwavelength resolution, based on surface plasmons(SP) diffraction theory into spoof SP of THz region. In THz
regime, the curved depth profile of grooves from both sides of metal slit produce directional beaming and mimic SP at
the same time. By arranging the depth of grooves in traced profile, it is possible to optimize the focal position in THz
region without changing the size of structure. It is performed numerical simulation of a designed structure through finite-difference
time-domain (FDTD) method and shows the subwavelength imaging of the designed position. In addition, the
change of focal length and the relative Ex phase are observed in the simulation and help to comprehend a subwavelength
1D slit-groove-based metamaterials in THz regime.
Negative: Index, Permittivity, and Refraction
Negative refractive index in doped semiconductors via electromagnetically induced mixed-parity transitions
Show abstract
The existing Quantum Optics- based models of negative refractive index in atomic-vapor medium (e.g. Ne,
Na) require unrealistically strong magnetic response of atoms combined with high atomic density. In
contrast to these gas-based models, our approach explores solid-state n-type semiconductor with well-defined
hydrogen-like donor atomic states within the band gap. Based on methods of Quantum Optics, we
have found that optically transparent indium oxide is negative refractive index material if doped with tin
and zinc (In2-x Snx/2 Znx/2 O3 (zinc-doped ITO)). The desirable negative refractive index effect is due to
coherent coupling an electric dipole transition with magnetic transition with proper detunings of the probe
and support laser beams (A.-G. Kussow and A. Akyurtlu, Int. J. Mod. Physics (2010)). The calculations
demonstrate the feasibility of the effect at ~ 10 THz with extremely high figure of merit FOM >> 10.
A three-dimensional negative refractive index medium operated at multiple-angle incidences
Show abstract
We present a negative refractive index medium (NRIM) operating at multiple-angle incidences by
expanding a conventional planar metamaterial to a three-dimensional (3D) structure. The proposed 3D
NRIM is comprised of semi-spherical metal shells and planar plamonic wires, thus giving rise to
negative magnetic permeability and negative electric permittivity, respectively. Our results show that
reflectance (transmittance) peaks slightly which locate the region of negative refraction index are
insensitive to the incident angles from 0° to 45° and the polarization of the excitation wave at a certain
range of frequencies. Such pseudo-isotropic NRIM may be exploited for superlens and antenna
applications.
Material parameters of optical metamaterials formed by nano-fishnet structures
Show abstract
The material parameters of nano-fishnet optical metamaterials are evaluated numerically through
extraction from reflection and transmission coefficients of structures consisting of multiple nano-fishnet
pairs. For extraction the Nicholson-Ross-Weir method was modified. Effects of
convergence with increase of number layers are discussed. Bulk electrodynamics parameters of
the structure are discussed.
Characteristics of surface modes in singly negative metamaterial waveguides
Show abstract
Metamaterials can be classified into doubly negative materials and singly negative media according to their number of
negative constituent parameters. Contrary to the doubly negative media in which light can propagate just like in
dielectric layers, incident light to the singly negative materials cannot transmit through them. This opaque property,
however, can be overcome by using the interfaces between different kinds of singly negative media, i.e., permittivity-negative
and permeability-negative ones. In this paper, we investigate what kinds of surface-guiding modes such
interfaces can support and see what their unique features are.
Transformation Optics and Cloaking
Maxwell fisheye and Eaton lenses emulated by a microdroplet
Show abstract
Despite strong experimental and theoretical evidence supporting superresolution imaging based on microlenses, imaging
mechanisms involved are not well understood. Based on the transformation optics approach, we demonstrate that
microlenses may act as two-dimensional fisheye or Eaton lenses. An asymmetric Eaton lens may exhibit considerable
image magnification, which has been confirmed experimentally.
Poster Session
Analysis of plasmon-polariton band structures of T-shaped plasmonic gratings
Show abstract
We study plasmon-polariton band structures theoretically for T-shaped plasmonic gratings. We analyze the structure
using Fourier expansion and perform numerical simulation using Rigorous Coupled Wave Analysis (RCWA). A detailed
derivation of equations which can be used to control the momentum gap behaviour using Fourier transform is given. A
structure gap is introduced in the post of the T-shaped plasmonic grating and it is found that the size of this gap plays an
important role in controlling the plasmon-polariton band gap and group velocities. We have found that the plasmon
mode can be decupled with light when the upper post is displaced by half a period. Thus, such a structure can be used as
plasmonic decupler. Furthermore, by displacing the T-shaped post we can tune the plasmon-polariton band gap and
group velocity in a non-monotonic manner. We obtain energy band gaps ranging from 0.4eV to 0eV by changing the size
of the structure gap from 0 to 330 nm and from 0.115eV to 0.068eV by displacing the post of the T-shaped structure
from 0 to 500 nm. We also obtain tunable group velocities ranging from one to several orders of magnitude smaller
than the speed of light in the vacuum. This asymmetric T-shaped plasmonic grating is expected to have applications in
surface plasmon polariton (SPP) based optical devices, such as filters, waveguides, splitters and lasers, especially for
applications requiring large photonic band gap.
A comparison of localization effects in one-dimensional disordered photonic bandgap structures
Show abstract
This paper presents a comparison of one-dimensional optical localization effects for both a disordered quarter-wave
stack and disordered non-quarter-wave stack. Optical localization in these one-dimensional photonic bandgap structures
is studied using the transfer matrix formalism, where each matrix is a function of one or more random variables. As the
random matrix product model tends to infinity, Furstenberg's theorem on products of random matrices tells us that the
upper (and positive) Lyapunov exponent exists and is deterministic. This Lyapunov exponent is clearly identified as the
localization factor (inverse localization length) for the disordered photonic bandgap structure. The Lyapunov exponent
can be calculated via the Wolf algorithm which tracks the growth of a vector propagated by the long chain of random
matrices. Numerical results of the localization factor are provided using the Wolf algorithm. In the randomized models,
layer thicknesses are randomized, being drawn from both a uniform probability density function and a binary probability
mass function. Significant notches are noted for a number of the results. The Lyapunov exponent can also be found
from Furstenberg's integral formula, which involves integration with respect to the probability distribution of the
elements of the random matrices, and the so-called invariant probability measure of the direction of the vector
propagated by the long chain of random matrices. This invariant measure can be determined numerically from a bin
counting technique similar to the Wolf algorithm. Invariant measure plots based on the bin counting method are shown
at selected frequencies.
General condition of transparent linearly transformed finite-embedded metamaterial slab
Show abstract
In this work, an investigation on the condition of non-reflecting boundaries for the finite-embedded coordinate
transformed media will be present. Under the restriction that the mapping functions of coordinate transformed media are
defined in a concept of extended two-dimensional forms and that the incident waves are two-dimensionally propagating
fields, we examined the existence of the conditions for non-reflecting boundaries in a finite-embedded coordinate
transformed media. If we restrict the mapping functions of the coordinate transformation to the linear transformation, the
non-reflecting boundary condition can exist in two-dimensional transformations but not in the extended two-dimensional
cases. Both the numerical and analytical investigations are present.
Electrically tunable omnidirectional photonic bandgap in one-dimensional photonic crystal with nonlinear composite materials and metamaterials
Show abstract
It is well known that the omnidirectional photonic bandgap (zero-n bandgap) can be realized in the one-dimensional
photonic crystals containing metamaterials. However, these omnidirectional photonic bandgaps are not tunable. In this
manuscript, we show that the electrically tunable omnidirectional photonic bandgap can be obtained in one-dimensional
photonic crystal with third-order nonlinear composite materials and linear metamaterials. It is demonstrated this photonic
crystal possesses electrically tunable photonic band structures based on the fact that the effective refractive index of
nonlinear composite material has electric-field dependence due to the existence of third-order nonlinear responses.
Moreover, we also showed that the photonic bandgap of this photonic crystal can be tuned by controlling the filling
fraction f of the composite.
Dynamics of anomalous ultrashort pulse splitting in nonlinear metamaterials
Show abstract
In this paper, we in detail investigate the dynamic behavior of pulse splitting in metamaterials (MMs) with a Kerr
nonlinear polarization, focusing on the anomalous propagation properties associating with the unique and engineerable
electromagnetic properties of such materials. The numerical results show that, the pulse symmetric splitting in MMs will
occur for the case of defocusing nonlinearity with anomalous dispersion due to the negative refractive index; while it
will appear for the case of focusing nonlinearity with normal dispersion in ordinary materials. Moreover, our further
analysis shows that, like the case in ordinary materials, the inclusion of self-steepening (SS) effect with positive value
gives rise to the asymmetry between the leading and trailing pulses, but the relative magnitudes of the two peaks are
reversed, namely, the leading pulse is higher than the trailing pulse. However, the negative SS does opposition.
Transverse modulation instability of copropagating light beams and the bright and dark spatial solitons in nonlinear metamaterials
Show abstract
Through using the standard split-step Fourier method, it is found that the transverse modulation instability (MI)can
develop when beams copropagate in the positive- and the negative-index region of the metamaterials (MMs) respectively
and it is equivalent with the temporal MI in the case of two pulses copropagate in the anomalous and normal dispersion
regions of the optical fibers respectively, which is meaning that bright and dark electromagnetic spatial solitons may
generate simultaneously. Furthermore, it is confirmed that the bright and dark electromagnetic spatial solitons may even
generate simultaneously when beams copropagate in MM, which is a new way to generate spatial soliton pair for there is
only leading to the generation of bright or dark spatial solitons in conventional material when two beams copropagate.
Rigorous analysis of non-magnetic cloaks
Show abstract
Nonmagnetic cloak offers a feasible way to achieve invisibility at optical frequencies using materials with only electric
responses. In this letter, we suggest an approximation of the ideal nonmagnetic cloak and quantitatively study its
electromagnetic characteristics using a full-wave scattering theory. It is demonstrated that the forward scattering of the
impedance matched cloak increases dramatically as the thickness of the cloak decreases. Nevertheless, it is still possible
to effectively reduce the total scattering cross section with a very thin cloak whose impedance is not matched to the
surrounding material at the outer boundary. Our analysis also provides the flexibility of reducing the scattering in an
arbitrary direction.
Effective electromagnetic parameters of two-dimensional dielectric photonic crystal within band gap
Show abstract
We have investigated the effective electromagnetic parameters of a two-dimensional photonic crystal even though the
wavelength is on the order of its lattice constant. For the photonic crystal within the first band gap, negative effective
permittivity or negative effective permeability has been found. Utilizing the Finite-difference time-domain method, a flat
slab imaging for TE waves in the near field has been demonstrated for the photonic crystal with effective negative
permittivity which is similar to silver superlens for TM waves. Based on these results, we can conclude that photonic
crystals in a certain frequency region can indeed mimic not only double-negative but also single-negative metamaterials.
Green's function integral equation method for propagation of electromagnetic waves in an anisotropic dielectric-magnetic slab
Show abstract
We extend the Green's function integral method to investigate the propagation of electromagnetic waves
through an anisotropic dielectric-magnetic slab. From a microscopic perspective, we analyze the interaction
of wave with the slab and derive the propagation characteristics by self-consistent analyses. Applying the
results, we find an alternative explanation to the general mechanism for the photon tunneling. The results
are confirmed by numerical simulations and disclose the underlying physics of wave propagation through
slab. The method extended is applicable to other problems of propagation in dielectric-magnetic materials,
including metamaterials.
Study of surface electrical properties of InAlGaAs structures grown on InP substrates
Show abstract
Room temperature photoreflectance (PR) was used to investigate the energy gaps transition, the surface state densities
and the surface barrier height of InxAlyGa1-x-yAs, in a series of epitaxial surface intrinsic-n+ structures with different Al
concentration. Features of Franz-Keldysh oscillations originating from the built-in electric field in the intrinsic top layer
were observed. Based on the thermionic emission theory and current-transport theory, the surface state density can be
determined from the square of maximum electric field as a function of various pump beam flux intensities.
A compact transmission-line metamaterial bandpass filter with ultra-wide-bandwidth for 60 GHz application
Show abstract
We present an ultra-wide band bandpass filter at 60 GHz by utilizing transmission-line metamaterial comprises an
open and a short resonator. The cornerstone of this ultra-wide-band bandpass filter is founded on the coupling between
the short and open resonators at their resonant states. Our simulation result manifests that the coupled short and open
resonators provide a passband by combining a left-handed region and a right-handed region, and thus achieve a
bandwidth of 6.2 GHz between 57.4 GHz and 63.6 GHz. Further, the stop band is widely extended down to DC and up to
109.4 GHz. Such characteristic is applicable for the 60 GHz wireless communication.