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- Front Matter: Volume 6638
- Surface Plasmons
- Optical Magnetism and NIMs
- NIMs
- Composites, Interfaces, and Materials
- Fundamentals and Concepts
- Luminescence, Gain, and Lasing
- Devices and Systems
- Poster Session
Front Matter: Volume 6638
Front Matter: Volume 6638
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This PDF file contains the front matter associated with SPIE Proceedings Volume 6638, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.
Surface Plasmons
Two-dimensional plasmonic metamaterials
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Fabrication of three-dimensional negative refractive index materials in the visible range faces numerous technological
challenges. On the other hand, many new concepts and device ideas in the optics of metamaterials may be demonstrated
much easier in two spatial dimensions using surface plasmon polaritons. Here we demonstrate these concepts and
devices using novel multilayer two-dimensional photonic materials consisting of alternating layers of positive and
negative refractive index. By changing composition and geometry of the layers, the effective anisotropic refractive index
of the material may be continuously varied locally from large negative to large positive values. This approach may find
applications in many novel nanophotonic devices, which enable efficient control of light propagation on submicrometer
scale. This becomes possible because of the considerably improved figure of merit of the plasmonic metamaterials
compared to the typical figures of merit of their three-dimensional counterparts.
Fabrication of plasmonic waveguides for device applications
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We report on experimental realization of different metal-insulator geometries that are used as plasmonic waveguides
guiding electromagnetic radiation along metal-dielectric interfaces via excitation of surface plasmon polaritons (SPPs).
Three configurations are considered: metal strips, symmetric nanowires and nanowire pairs embedded in a dielectric, and
metal V-shaped grooves. Planar plasmonic waveguides based on nm-thin and μm-wide gold strips embedded in a
polymer that support propagation of long-range SPPs are shown to constitute an alternative for integrated optical
circuits. Using uniform and thickness-modulated gold strips different waveguide components including reflecting
gratings can be realized. For applications where polarization is random or changing, metal nanowire waveguides are
shown to be suitable candidates for efficient guiding of arbitrary polarized light. Plasmonic waveguides based on metal
V-grooves that offer subwavelength confinement are also considered. We focus on recent advances in manufacturing of
nanostructured metal strips and metal V-grooves using combined UV, electron-beam and nanoimprint lithography.
Optical metamaterials based on thin metal films: from negative index of refraction, to enhanced transmission, to surface wave guidance
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Optical metamaterials characterized by several unique properties are introduced and characterized. The structures
comprise continuous metal films sandwiched between dense periodic arrays of optically thin metal strips or patches
separated by a small distance. The structures' electromagnetic properties are described by means of a modification of the
cavity model typically used to characterized microwave patch antennas. It is shown that the presented structures can
operate as negative index metamaterials that comprise deeply subwavelength periodic unit cells, are tunable for
operation in the near-infrared and visible spectra, and can be manufactured using standard methods and materials. In
addition, the presented structures can operate as an optical filter that, due to the presence of several resonances, transmits
fields for certain (controllable) wavelength bands, which are (nearly) independent of the angle of incidence and
polarization. The presented structures also can support arbitrary polarized surface waves that can have a high
wavenumber and can exhibit unusual dispersion relations.
En route to low loss nanoplasmonics: elongating surface plasmon propagating length without gain
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We have demonstrated that an addition of highly concentrated rhodamine 6G chloride dye to the PMMA film adjacent to
a silver film causes three-fold reduction of the imaginary part of the dielectric constant of Ag (absorption loss in metal)
and 30% elongation of the propagation length of surface plasmon polaritons (SPP). The possibility to elongate the SPP
propagation length without optical gain opens a new technological dimension to low-loss nanoplasmonics.
Optical Magnetism and NIMs
Photon tunneling at material boundary by positive permeability metamaterials
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The application of the magnetic metamaterials with positive (over one) permeability is proposed. The Brewster effect is
one of the methods to eliminate unwanted reflection occurred at the material boundary of different indices. The message
in this paper is that the magnetic responses of the metamaterial enable us to realize the Brewster effect not only for p-polarized
light but also for s-polarized one. This new finding has the significant consequence that if we could induce the
Brewster effect for both p- and s-polarized light simultaneously, the light could pass though the material boundary
without any reflection loss at all. Based on this idea, we theoretically demonstrate the Brewster windows for both
polarizations by introducing a uniaxial magnetic metamaterial whose values of the permittivity and permeability depend
on the direction of the material. Numerical simulations prove that this metamaterial-based optical device realizes the
reflectionless light transmission through the interface between vacuum and glass.
Slow light in negative-index waveguide heterostructures
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We introduce an efficient method for slowing and stopping/storing light, which is based on wave propagation along a
slowly axially varying, adiabatically tapered, negative refractive index metamaterial heterostructure. We analytically
show that the present method can, in principle, simultaneously allow for broad bandwidth operation (since it does not
rely on group index resonances), large delay-bandwidth products (since a wave packet can be completely stopped and
buffered indefinitely) and high, almost 100%, in/out-coupling efficiencies. Moreover, by nature, the presented scheme
invokes solid-state materials and, as such, is not subject to low-temperature or atomic coherence limitations. This method
for trapping photons conceivably opens the way to a multitude of hybrid, optoelectronic devices to be used in 'quantum
information' processing, communication networks and signal processors, and may herald a new realm of combined
metamaterials and slow light research.
NIMs
The effects of dispersion, diffraction, and nonlinearity management in negative index materials
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We analyze linear and nonlinear propagation in negative index materials by starting from a dispersion relation and
by deriving the underlying partial differential equations (PDEs). Transfer function for propagation is also derived in
spatial frequency domain. Using existing numerical methods, based on fast Fourier-Bessel transforms, we study the
stability of the solitary wave solutions. Nonlinearity and dispersion management are then incorporated to find stable
solutions of the underlying PDEs.
Mean field theory of metallo-dielectric photonic crystals with magnetic components: the long-wavelength limit
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Recently there has been developed a homogenization theory of photonic crystals, based on the averaging of
the Maxwell Equations within the unitary cell. It leads to the bianisotropic response with the electric displacement D and the magnetic induction B
vectors both depending linearly on the electric E and magnetic H fields. Despite the generality of this theory,
the case of naturally magnetic ingredients has not been considered. For this reason, in this work we extend
the aforementioned theory in this sense. In this way the ingredients of the unitary cell are characterized by
a permeability, in addition to a generalized complex conductivity. These parameters are assumed to be given
for every position in the unitary cell of the photonic crystal. We conclude that in the presence of naturally
magnetic ingredients the medium response is still bianisotropic, but now the material dyadics depend on both
the permeability and complex conductivity. Numerical results are given for the case of a one-dimensional photonic
crystal with ferrite layers.
Fabrication and applications of negative refractive index matermaterials with chiral properties
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Realizable artificial medium with negative permittivity,
permeability and refractive index are fabricated by
introducing inclusions significantly smaller than the
wavelengths of excitation into an archival host medium.
Negative refractive index media normally posses a small
degree of chirality associated with the split-rings. However
in order to enhance the chirality of the artificial media, the
split rings can be replaced by spirals.
Recent work has shown that well controlled chiral media
can be fabricated using available semiconductor techniques
that have been modified to produce these structures.
Specifically the glancing angle deposition technique
(GLAD) has been shown to be well suited to producing
these types of chiral structures.
Novel devices made from metamaterials that also possess
chirality are considered. When chiral properties are
included in a negative refractive index slab, with n = -1,
two rays are refracted in the slab. The distance between the
two corresponding focal lines is determined by the
magnitude of the chiral parameter. Thus this negative
refractive index lens can also be used to measure the chiral
parameter. At the focal lines small cross polarized
components also exist.
Based on the complete model expansion of the field at the
chiral-chiral (or free space-chiral) interface it is shown that
line sources also excite several species of lateral waves that
are associated with total internal reflection. Since the
refractive index is assumed to be negative, rays incident
upon the chiral slab at the critical angles for total internal
reflection, θ1 and θ2, are refracted parallel to the interface
in the backward direction, resulting in θR1 and θL1 equal to -90°. Thus the image and the source are on the same
side of the negative refractive index chiral slab and the
device behaves like a reflector.
Composites, Interfaces, and Materials
Organic electro-optic/silicon photonic materials and devices
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Photonic technologies hold the promise of transformative advances in the telecommunications, aerospace, and
computing industries. In particular, organic materials displaying electro-optic coefficients an order of magnitude larger
than the current industry standard inorganic materials (r33 ≥ 300 pm/V) may hold the key to the development of cheap,
high bandwidth, and highly integratable electro-optic devices. The pertinent linear and nonlinear optical properties of
such organic second-order nonlinear optical materials are highly dependant on their dielectric properties as well as the
extent of dipolar order that can be created. Here, theoretical approaches to the simulation of highly active organic
electro-optic materials are described. Such simulations assist understanding and may be used to predict optical properties
facilitating the rational design process. Improved ordering schemes, such as laser-assisted electric-field-poling may help
in the translation of large chromophore hyperpolarizability values into large r33. Recent results also suggest that
incorporation of these improved organic materials into new hybrid organic/silicon device designs may lead to
dramatically reduced device operational voltages and create opportunities for the development of new device
functionality.
Effect of interchain interaction on linear optical properties of poly(thienylenevinylene)
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Optical absorption spectra of poly(thienylenevinylene) (PTV) conjugated polymers are measured at room temperature
in spectral range 400 to 800 nm. A dominant peak located at 575 nm and a prominent shoulder at
614 nm are observed. Equilibrium atomic geometries of PTV conjugated polymers are studied by first principles
density functional theory (DFT). Electron energy structure is obtained through self-consistent solution of eigen
energy problem using ab initio ultrasoft pseudopotentials and generalized gradient approximation method. This
is a non traditional approach for complex organic systems which is shown to be very promising especially for
optical simulations. Linear optical absorption is calculated within Random Phase Approximation (RPA) picture.
By comparative analysis of experimental and theoretical data it is demonstrated that dominant contribution to
the optical excitations of PTV in visible spectral range are related to the delocalized electrons within the polymer
chains. Obtained optical data together with equilibrium geometry analysis indicate that interchain interactions
substantially effect electronic structure and optical absorption of PTV conjugated polymers.
Semiclassical theory of hyperlensing and cloaking
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We develop the ray optic Hamiltonian for a cylindrically anisotropic medium such as the hyperlens using the
semiclassical approximation, which reveals an interesting spiralling behaviour of ray trajectories and also gives
an alternative explanation to the subdiffraction far field imaging behaviour of the device. The Hamiltonian can
be further used to derive the material parameters needed for non magnetic cloaking. Numerical simulations of
gaussian beam scattering from these devices confirm the respective semiclassical results.
Fundamentals and Concepts
Light pressure on chiral sculptured thin films
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Sculptured thin films (STFs) are porous thin films manufactured by physical vapor deposition processes, and
possess a morphology that is engineered at the nanoscale. When a circularly polarized plane wave is obliquely
incident on a chiral STF, the Maxwell stress dyadic exhibits a decreasing periodic variation across the thickness
of the film. Normal and tangential surface tractions exist on the two faces of the chiral STF, as well as a net
normal pressure across the film. These stresses are affected by the incidence angle of light, and are maximized
when (i) the incident plane wave and the chiral STF are co-handed, (ii) the wavelength falls within a regime
called the Bragg regime, (iii) the ratio of film thickness to the structural period of the chiral STF reaches a
saturation value, (iv) the deviation from normal incidence is small, (v) the loss factor in the chiral STF is as
low as possible, and (vi) the vapor incidence angle is optimally chosen during film deposition.
Swamping of circular Bragg phenomenon revealed by durations and average speeds of videopulses transmitted through chiral sculptured thin films
Show abstract
We studied trends in three measures of both duration and average speed of optical videopulses transmitted
through chiral sculptured thin films (STFs). The films, a class of nanoengineered materials which consist of
parallel helical nanowires grown on a substrate, were taken to be linear or nonlinear with an intensity-dependent
refractive index. We used a finite-difference algorithm to compute the evolution of the pulse shapes in the
time domain. The durations of videopulses transmitted through chiral STFs tended to decrease with increasing
carrier wavelength, while the average speeds tended to increase or remain roughly constant with increasing
carrier wavelength. The durations and average speeds were similar irrespective of whether the incident pulse
possessed a left or right circularly polarized carrier plane wave. That is, the circular Bragg phenomenon−due
to a circular polarization dependent photonic bandgap exhibited by chiral STFs over a bandwidth called the
Bragg regime−did not affect the results to any meaningful extent, in contrast to previous work. We attribute
this finding to the wide bandwidth of the incident pulses swamping the Bragg regime.
Luminescence, Gain, and Lasing
On the possibility of gain control and special solitons in metamaterials
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A discussion of gain control up to the THz frequency range is presented together with a study of diffraction-managed
solitons in metamaterials. Full dynamical simulations are used at every stage to illustrate the principles being evolved.
An interesting approach based upon the mapping of the complex frequency-plane onto the complex wave number-plane
is given as a way of demonstrating whether the offset of loss by using gain leads to a stable material. Nonlinear
behaviour is addressed through the possibility of soliton formation under the conditions for which nonlinear diffraction
can play a role whenever an attempt to manage the diffraction is made with a suitable combination of left-handed and
right-handed materials. All of this activity requires the modeling of curious artificial molecules but the computational
outcomes inspire confidence that is exemplified with exciting illustrations. The remit of control, exercised through
external influences such as an applied magnetic field, and cavity formation is briefly explored.
Diffraction and dispersion management in active nanostructured metamaterials
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We explore the perspectives offered by nanoplasmonic metamaterials for manipulation of optical signals at the
nanoscale. It is shown that in contrast to conventional dielectric waveguides, plasmonic and anisotropy-based
waveguides support a number of highly-confined optical modes even when the waveguide size is much smaller than the
wavelength. The effective modal indices in these systems can be either positive or negative and are strongly affected by
material composition and waveguide size, providing a mechanism for manipulating the phase velocity and diffraction
limit at the nanoscale. In active metamaterials, the combined effect of waveguide- and material-induced dispersions leads
to a versatile control over the group velocity which can be changed from negative to large or small (in comparison with
the speed of light in vacuum) positive values by a relatively weak modulation of material properties. In the end, the
active metamaterial provide a unique platform for independent manipulation of group and phase velocities of
electromagnetic radiation in sub-diffraction areas.
Limits of luminescence efficiency enhancement by surface plasmon polaritons
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We develop a rigorous theory of the enhancement of spontaneous emission from a light-emitting device via coupling the
radiant energy in and out of surface plasmon polaritons (SPPs) on the metal-dielectric interface. We show that while the
efficiency of coupling into the SPP mode can be quite high, the radiative efficiency of the SPP itself is relatively low,
with a substantial fraction of the energy lost in the metal. Using the GaN/Ag system as an example we obtain easy-to-interpret
analytical results that unequivocally indicate that using SPP pays off only for emitters that have medium-to-low
luminescence efficiency; thus the SPP applications should be limited to those in sensing and analysis rather than in the
development of efficient light sources.
Dye-doped porous silica as an all solid state device for random lasing
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The context of this work is the development of solid state materials with optimized microstructures for investigation
of the random laser emission. We focused our attention on dye doped silica whose porosity allows controlling
the light transport mean free path.
Synthesized materials were silica monoliths prepared through sol-gel processing in the presence of a polymer
that induces porosity through a spinodal phase separation. This technique allows the preparation of bulk samples
with a controlled pore size varying from several microns to less than 100 nm. These samples were doped through
impregnation with a naphthalimide fluorescent dye solution. Homogeneous dispersion of the dye was achieved
using a silanated derivative leading to its homogeneous deposition as a thin film at the surface of the pores. This
gives strongly fluorescent and diffusive materials.
Optical properties of the samples were characterized using the 425.84 nm line of a dye laser. FWHM reduction
of the sample emission was observed as a function of the pumping power, showing a typical behavior for a random
laser in the weakly localized regime. Due to the versatility of the synthesis, the efficiency of the random lasing
effect was investigated as a function of the materials microstructure.
Devices and Systems
Characterization and excitation of a nano-scaled plasmonic coupler with co-directional phase and contra-directional power flow
Show abstract
A nano-scaled coupled-waveguide coupler based on the guidance of surface plasmon-polaritons (SPPs) is proposed,
designed and simulated at optical frequencies. The basic structure of the coupler comprises layered
dielectric materials and thin silver films, which serve as two stacked nano-transmission lines to achieve broadside
coupling. The key property of this design is that it operates based on the principle of contra-directional coupling
between a left-handed and a right-handed guided wave, giving rise to supermodes that are characterized by
complex-conjugate propagation constants (even in the absence of losses), where the attenuation constant signifies
the rate of coupling instead of the conventional power dissipation. The resulting exponential attenuation along
the coupler leads to dramatically reduced coupling lengths compared to previously reported co-directional SPP
couplers (e.g. from millimeters to sub-microns). Given its size, the device lends itself to form the building block
of a functional matrix such as a switching array in nanophotonics applications, for example. In order to verify the
contra-directional coupling theory and to characterize our design, we also propose and examine several possible
excitation schemes, such as using a plasmonic dipole antenna and a grating structure to excite the SPP mode.
Additionally, a measurement topology utilizing a curved plasmonic waveguide is also presented in this paper.
Optical hyperlens: far-field imaging beyond the diffraction limit
Show abstract
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.
Poster Session
Optical properties of metamaterials based on porous channel photonic structures and applications for optical devices
Show abstract
Optical properties of a new kind of metamaterials based on hierarchically organized mirror channels
with semitransparent walls, metamirror structures (MMS) are considered. Despite the difference in physical
mechanisms, some properties of MMS i.e. transmission and reflection are close to that exhibited by left-handed
materials. The ray tracing is considered for different MMS geometries and types. It is shown that one-step
reflective 2D MMS based on rectangular elementary cells being properly curved possess lens properties and
MMS lens generalized law is derived. Properties of a mirror lens prototype with the finite meta-focus position
made from one layer 2D MMS with reflecting walls are evaluated theoretically and experimentally. Micro-machine
mirror systems and modified macroporous structures are discussed as mirror lens devices.
Electrically controlled Bragg resonances of an ambichiral electro-optic structure: oblique incidence
Show abstract
The Pockels effect can be used to tune the effective birefringence of ambichiral structures made of electro-optic
materials with 42m point group symmetry, when a dc electric field is applied parallel to the axis of
nonhomogeneity. The reflectances and transmittances of such an ambichiral structure can be calculated through
the solution of a boundary-value problem. The Bragg resonance peaks, for different circular-polarized-incidence
conditions, blueshift as the angle of incidence increases.
Equilibrium geometries and electronic structure calculations of divalent lead Pb(II) complexes with paramagnetic organic ligands
Show abstract
During the past several decades enormous effort has been dedicated to experimental and theoretical studies of metal-radical
organic complexes. Equilibrium geometries and electron energy structure of divalent lead Pb(II) complexes with
ortho-semiquinone radicals have been calculated by generalized gradient approximation method (GGA) within density
functional theory (DFT). Optical absorption spectra were calculated within random phase approximation (independent
particles picture). Predicted substantial modification of the absorption spectra in visible infrared regions is attributed to
the atomic configuration changes and to modifications of electronic energy due to the metal-radical coupling. The results
of the calculations are discussed in comparison with available experimental data on electron spin resonance spectra of
Pb(II) with paramagnetic ortho-semiquinone ligands.