This PDF file contains the front matter associated with SPIE Proceedings Volume 8070, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

We report the generation of THz pulses from arrays of silver nanoparticles when irradiated by femtosecond laser pulses. We suggest that this effect arises from the emission of photoelectrons by multi-photon excitation and subsequent acceleration of these emitted electrons by ponderomotive forces associated with the optical fields of the plasmons in the metallic nanostructures.

Passive real-world waveguiding structures are inevitably lossy, and some of them, such as plasmonic waveguides, exhibit even very strong attenuation. Losses can be compensated by including active components with gain. In this paper we discuss properties of waveguiding structures with generally complex dielectric permittivity distributed across their cross-section. In particular, we focus on the existence of modes that exhibit balance between loss and gain and that can propagate unattenuated provided the suitable conditions are satisfied. Specifically, we examine power transmission in the structures with a balance of loss and gain supporting lossless propagation of two modes. We demonstrate that when both modes are excited simultaneously, the total transmitted power is not conserved as the modes propagate along the waveguide. We also show that even if one of the modes propagates with gain, the maximum attainable transmitted power is strongly influenced by back-reflections from the interface with the passive output waveguide. We also discuss the conditions for the existence of an un-attenuated propagation of a confined surface mode supported by the gain/loss nature of these photonic structures.

We propose different optical antenna structures for enhancing and confining the magnetic optical field. A common feature of these structures are concave corners in thin metal films as locations of the enhanced magnetic field. This proposal is inspired by Babinet's principle as the concave edges are the complementary structures to convex metal corners, which are known to be locations of a strongly enhanced electric field. Bowtie antennas and the bowtie apertures of appropriate size were shown to exhibit resonances in the infrared frequency range with an especially strong enhancement of the electrical field in the gap between 2 convex metal corners. We show by numerical calculations, that the complementary structures, the complementary bowtie aperture - the diabolo antenna - and the complementary bow tie antenna - two closely spaced triangular apertures in a metal film with a narrow gap between two opposing concave corners - exhibit resonances with a strongly enhanced magnetic field at the narrow metal constriction between the concave corners. We suggest sub-wavelength circuits of concave and convex corners as building blocks of planar metamaterials.

From a microscopic point of view, we theoretically investigate fishnet metamaterials. We formulate the construction of the fundamental Bloch mode by tracking the flows of energy through the fishnet structure. The analysis is supported by a closed-form semi-analytical model based on surface-plasmon coupled-mode equations. The model provides an accurate formula for the fishnet refractive index, including the real (negative-valued) and imaginary parts. The model simply explains how the surface plasmon modes couple in the structure and it shines new light on the fishnet negative-index paradigm at optical frequencies. It possesses broad flexibility in geometrical and material parameter tailoring of fishnet properties, even including the gain-assisted case.

We propose the method of effective parameters retrieval based on the Bloch mode analysis of periodic metamaterials. We perform the surface and volume averaging of the electromagnetic field of the dominating (fundamental) Bloch mode to determine the Bloch and wave impedances, respectively. We show that our method is able to retrieve both material and wave EPs for a wide range of materials, which can be lossy or lossless, dispersive, possess negative permittivity, permeability and refractive index values. It is simple and unambiguous, free of the "branch" problem, which is an issue for the reflection/transmission based method and has no limitations on a metamaterial slab thickness. The method does not require averaging different fields' components at various surfaces or contours. The retrieval of both wave and material EPs is performed within a single computational cycle, after exporting fields on the unit cells facets or in its volumes directly from Maxwell's equations solver.

We demonstrate an improvement of the plane wave expansion method treating two-dimensional photonic crystals by applying Fourier factorization with generally elliptic polarization bases. By studying one example of periodically arranged cylindrical elements, we compare our approach to the classical Ho method in which the permittivity function is simply expanded without changing coordinates, and to the normal vector method using a normal-tangential polarization transform. The compared calculations clearly show that our approach yields the best convergence properties owing to the complete continuity of our distribution of polarization bases.

We have succeeded in aligning gold nanoparticles (Au NPs) in three-dimensions using tobacco mosaic virus (TMV) in order to realize new optical properties. TMV is a tube-shaped plant virus about 300 nm in length with an outer- and inner-diameter of 18 nm and 4 nm. We genetically fused material-binding peptides that can promote metal crystallization, namely a gold-binding peptide (GBP) and a titanium-binding peptide (TBP), to the outer-surface of TMV. By reducing potassium chloroaurate with sodium borohydride in the presence of the engineered viruses in 5% acetic acid solution, Au NPs were deposited on the outer-surface of the viruses. Using TBP-fused TMV, NPs of 5 nm were obtained, with a standard deviation smaller than those deposited on wild-type TMV. The diameter of the NPs on GBP-fused TMV was 10 nm. These results indicate that genetically-modified TMVs are promising templates for the construction of optical metamaterials.

We report on strong coupling between surface-plasmon polaritons and Rhodamine 6G molecules at room temperature. As a reference to compare with, we first determine the dispersion curve of (uncoupled) surface plasmon polaritons on a 50 nm thick film of silver. Consequently, we determine the dispersion curve of surface plasmon polaritons strongly coupled to Rhodamine 6G molecules, which exhibits vacuum Rabi splitting. Depending on the Rhodamine 6G concentration, we find splitting energies between 0.05 eV and 0.13 eV.

Rapid development of novel, functional metamaterials made of purely dielectric, plasmonic, or composite structures which exhibit tunable optical frequency magnetic responses creates a need for new measurement techniques. We propose a method of actively measuring magnetic responses, i.e. magnetic dispersion, of such metamaterials within a wide range of optical frequencies with a single probe by exciting individual elementary cells within a larger matrix. The probe is made of a tapered optical fiber with a radially corrugated metal coating. It concentrates azimuthally polarized light in the near-field below the apex into a subwavelength size focus of the longitudinal magnetic field component. An incident azimuthally polarized beam propagates in the core until it reaches the metal stripes of constant angular width running parallel to the axis. For a broad frequency range light-to-plasmon coupling is assured as the lattice constant changes with the radius due to constant angular width. Bound plasmonic modes in slits between the metal stripes propagate toward the apex where circular currents in stripes and displacement currents in slits generate a strong longitudinal magnetic field. The energy density of the longitudinal magnetic component in the vicinity of the axis is much stronger than that of all the other components combined, what allows for pure magnetic excitation of magnetic resonances rather than by the electric field. The scattered signal is then measured in the far-field and analyzed.

We consider two kinds of plasmonic nanolenses which focus radially polarized Laguerre-Gauss beam into subwavelength spot. The first one is free-standing opaque metal layer with concentric grooves on both sides [Phys. Rev. Lett. 102, 183902 (2009)]. The second has slits instead of grooves thus concentric rings have to be integrated with dielectric matrix. Constructive interference of far-field radiation of SPPs scattered on the back side of the lenses gives subwavelength size foci approaching the Rayleigh resolution limit. We investigate transmission and focusing properties of considered metal structures. Choice of appropriate metal such as silver, gold, copper or aluminum strongly affects transmission. Parameters of surface structure determine efficient photon-plasmon coupling and plasmon scattering phenomenon thus influence both transmission and focusing effect. Finally, the choice of dielectric function of surrounding medium gives another degree of freedom to fulfill momentum matching condition for resonant photonplasmon interaction. In this paper, taking into account the above parameters, we show an optimization procedure, which leads to high transmission, tight focal spot and large focal length of the considered plasmonic nanolenses.

We identified nanostructured devices sustaining subwavelength diffraction-free beams with grazing propagation. The components of the optical assembly are a metal-dielectric multilayer stack deposited on a solid transparent substrate. Launched from the substrate, the nondiffracting beam is resonantly transmitted though the stratiform medium leading to light confinement and wave amplification around the beam axis near the top end. Potential applications include optical trapping, biosensing, and nonlinear optics.

We present a method of fabricating aperture tapered-fiber metal-coated SNOM probes with a corrugated core surface which assures efficient photon-to-plasmon conversion and thus high energy throughput. High energy throughput allows for a small apex aperture and high resolution. The procedure consists of recording of Bragg grating in the to-be-tapered part of a Ge-doped silica fiber and chemical etching with the Turner method. Bragg gratings are recorded with UV light through nearly sinusoidal phase masks of chosen lattice constants. The refractive index contrast in the Bragg grating differentiates the etch rate of the Ge-doped hydrogenated fiber core in exposed and unexposed parts by about 100 nm/min at room temperature.

Slowing light has arisen increasing attentions due to its applications for optical switching, optical hard disk and enhanced photon-matter interaction, especially the system utilizing left-handed tapered waveguide (LHWG) to demonstrate either oscillatory mode or surface plasmon polariton (SPP) mode which are the most possible candidates to be commercialized. But both of them suffer from the loss coming from metal to limit the time to trap photons in the LHWG. Hence, we hire highly contrast dielectric metamaterials as LHWG to reduce the Ohmic loss from metal and demonstrate slowing light effect. Our results are confirmed by introducing E-field (or H-field) distribution and power flow recording in CST simulation software.

Double asymmetric split ring resonators (DA-SRRs) are composed of four separate asymmetric metallic arcs that share the same centre-of-curvature. These four arcs interact to produce very steep slopes in the reflection spectrum and also increase the number of trapped modes. This combination produces larger resonance quality-factors (Q-factors), making arrays of such resonators potentially useful for optical sensing.

In this paper we present the whole fabrication and characterization cycle for obtaining 3D metal-dielectric woodpile structures. The optical properties of these structures have been measured using different setups showing the need of considering e.g. border effects when planning their use in real-life devices. It was found that the behavior of the structures close to the edge is very different from the one in the middle. The existence of special features in the former spectra still needs to be completely understood and explained.

Metamaterials are composites consisting of artificial meta-atoms/metamolecules with typical sizes less than the wavelength of operation. One of the key properties that makes metamaterials distinctly different form the natural media is a very strong magnetic response that can be engineered in the visible and infra-red part of the spectrum. In this work we summarize our multipole expansion approach that can be used to describe analytically optical properties of metamaterials composed of, in particular, the split-ring and cut-wire resonators. An important feature of our formalism is the possibility of describing nonlinear response of a metamaterial, such as second harmonic generation, which arises due to induced high-order multipoles. Our model has recently been extended to the case of hybrid metamaterials composed of plasmonic nano-resonators coupled with quantum elements (such as quantum dots, carbon nano tubes etc). It has also been shown that apart from metamaterials various other physical systems can be successfully modelled within framework of the developed approach. For example, transient dynamics and steady-state regime of a nano-laser, as well as its stochastic properties (e.g. linewidth of generation) have been described using this model.

The influence of the lateral asymmetry of the double-wires on the macroscopic effective parameters of the metamaterial was investigated using the multipole model. Investigations have shown that the system dynamics is dominated by the largest wire, which plasmonic oscillations define the orientation and the strength of the microscopic currents in the system. As a result the magnetization of the material can be enhanced for certain asymmetric configurations of the constitutive double-wires.

We discuss the concept of infrared cloaking using nanosphere dispersed liquid crystal (NDLC) matematerial in cylindrical geometry. Preliminary results show that NDLC is a promising candidate for cloak design. Monte Carlo simulations are used for the design.

In recent years, transformation optics has become a very active new field. It has been popularized through the idea of J.B. Pendry that an invisibility cloak can be designed by transforming space and considering the corresponding equivalent material properties. Indeed, it is a deep property of the Maxwell's equations that they are purely topological (when written in the proper formalism) and that all the metric aspects can be encapsulated in the electromagnetic material properties. A direct consequence is that any continuous transformation of space can be encoded in an equivalent permittivity and permeability. In this paper, we discuss the meaning of transform optics to show how global quantities defined by geometric integrals are in fact left invariant by the transformation. Extending this principle beyond continuous transformations allows to design exotic optical devices such as the invisibility cloak. Another example of transformation optics devices are the superlenses : even if these devices were proposed a few years before the rise of transform optics, they are nicely interpreted as corresponding to a folding of the space on itself. It has been suggested that such devices allow a kind of "remote action" of the scatterers making possible things such as immaterial waveguides called "invisible tunnels". In this paper, we investigate numerically (using finite element modelling) the behaviour of invisibility cloaks and cylindrical superlenses to show some of their amazing possibilities but also to define some of their limitations.

Metal nanoparticle arrays offer the possibility to considerably surpass the optical field confinement of silicon waveguides. The properties of directional couplers composed of such plasmonic nanoarrays are analyzed theoretically, while neglecting material losses. It is found that it is possible to generate very compact, submicron length, high fieldconfinement and functionality devices with very low switch energies. We further perform a study of spatial losses in Ag nanoparticle arrays by obtaining the group velocity and the lifetime of the surface plasmon polaritons. The losses are determined for different host permittivities, polarizations, and for spherical and spheroidal particles, with a minimum loss of 12 dB/μm. The possibilities to compensate the losses using gain materials, and the added noise associated with that, is briefly discussed.

We propose a high-transmission dualband terahertz bandpass filter by exciting multiple resonances of a composite metamaterial. The filter is composed a single layer of metal-dielectric-metal artificial structure and possesses two pronounced passbands centered at 0.97 THz and 1.37 THz, respectively. Both the passbands show high transmissions up to 90 % and also excellent band-edge transitions in the special terahertz-gap regime based on the simulations. In addition, we promise an effective approach to manipulate such electromagnetic properties of the metamaterial through realizing all the mechanisms for each resonant mode of the metamaterial. A potential terahertz device, broadband terahertz bandpass filter with almost 0.5-THz bandwidth, after structural modulation from the same composite metamaterial is also delivered in this work.

Silicon is the primary material used for the fabrication of solar cells and it is responsible for about 40% of the cost. Metamaterials show promise in enhancing the performance of silicon solar cells thus, improving the efficiency. Here we report on the fabrication of a broadband, antireflective, conductive metamaterial capable of channeling light into a solar cell. As a precursor to making the metamaterial, standard p-n junctions were fabricated. Conventional phosphorus oxychloride (POCl₃) furnace diffusion was used to create the p-n junction. When the p-n junction was forward biased, the measured current exhibited a diode characteristic. The measured photocurrent response yielded an open circuit voltage for the p-n junction at 0.48 VDC. The metamaterial film was fabricated, placed atop the p-n junction and characterized. Initial tests showed that the metamaterial antireflective properties were on par with those of standard industrial single-layer silicon nitride coatings. Further testing is being performed to assess the full optical and electrical performance of the metamaterial film.

We have demonstrated numerically that the interface of a metal and uniformly magnetized two-dimensional photonic crystal fabricated from a transparent dielectric magneto-optic (MO) material possesses a one-way frequency range where only a forward propagating surface plasmon polariton (SPP) mode is allowed to propagate. The nonreciprocity at the interface is introduced by the MO properties of the photonic crystal that is fabricated from Bismuth Iron Garnet (BIG, Bi₃Fe₅O₁₂), a ferrimagnetic oxide which may be easily magnetically saturated by fields of the order of tens of mT. Therefore, this configuration allows to achieve sizable one-way bandwidth by using significantly smaller values of the external magnetic field than an analogous waveguide proposed by Yu¹ which makes such a waveguide favorable for design of diode-like elements in optical integrated circuits. By using simple analytical model we have determined one-way frequency range which is consistent with the results obtained previously by using a MO aperiodic Fourier Modal Method (MO a-FMM). To investigate transport properties of the structures within this frequency range we have implemented finite-difference time-domain(FDTD) method, that allows calculating the propagation of EM waves through media with full tensorial magneto-optic permittivity. We examined the unidirectional transport properties of the proposed one-way waveguide and studied how the nonreciprocity depends on boundary conditions, for instance, by placing a perfect conducting mirror at the end of one-way waveguide.

Aperture probes of scanning near-field optical microscopes (SNOM) offer resolution which is limited by a sum of the aperture diameter at the tip of a tapered waveguide probe and twice the skin depth in metal used for coating. An increase of resolution requires a decrease of the aperture diameter. However, due to low energy throughput of such probes aperture diameters usually are larger than 50 nm. A groove structure at fiber core-metal coating interface for photon-to-plasmon conversion enhances the energy throughput 5-fold for Al coated probes and 30-fold for Au coated probes due to lower losses in the metal. However, gold coated probes have lower resolution, first due to light coupling from the core to plasmons at the outside of the metal coating, and second due to the skin depth being larger than for Al. Here we report on the impact of a metal bilayer of constant thickness for coating aperture SNOM probes. The purpose of the bilayer of two metals of which the outer one is aluminum and the inner is a noble metal is to assure low losses, hence larger transmission. Using body-of-revolution finite-difference time-domain simulations we analyze properties of probes without corrugations to measure the impact of using a metal bilayer and choose an optimum bi-metal configuration. Additionally we investigate how this type of metalization works in the case of grooved probes.

We characterize the influence of surface roughness on resolution and on the transmission coefficient of double layered silver-TiO2 superlenses. Rough surfaces are modelled with a Gaussian statistics based on experimental AFM measurements of e-beam evaporated layers, whereas the rest of the analysis is numerical and is obtained using 2D FDTD. The roughness of a surface is described with the root-mean-square of its height and with the width of its autocorrelation function. Our modelling results confirm that surface roughness is a critical limiting factor for both superresolution and for large transmission efficiency.

We numerically evaluated the 3D PSF of stratified negative-index superlenses. We determined in terms similar to the Rayleigh criterion the limit of resolution characterizing these image formers. Under some circumstances, the limit of resolution may drop approximately one order of magnitude. We investigated this significant increase of the resolution power in detriment of reducing the depth of field.

The investigation is devoted to give proof to the simple idea, that a globular protein is a molecular machine. This machine effectively converts electromagnetic energy of thermal equilibrium radiation (TER) to energy of acoustic oscillations associated with low-temperature equilibrium fluctuations of protein structure. The laws of thermal equilibrium radiation , the activation process model and photon-to-phonon transformation mechanism in solid state are used to prove this idea. The absorbing ability of a globule is calculated for myoglobin and beta-hemoglobin macromolecules. It is shown, that up to 36 - 37 % of electromagnetic energy of thermal equilibrium radiation is conversed to energy of the phonon bath. Then the bath's energy is used to enable low-temperature equilibrium fluctuations of a globule. Thus, it is proved, that protein macromolecule is an acoustic resonator capable to store energy for structural transformations. So, a globular protein can be used as a metamaterial prototype for electromagnetic-acoustic energy conversion at low temperatures.

Coating lenses are membranes made of materials exhibiting negative index of refraction and deposited on other media with high dielectric constant ε₃. Unfortunately far-field imaging suffers from centrosymmetric aberrations. We propose a simple procedure to compensate partially deviations from ray-tracing perfect imaging in asymmetric metamaterial lenses. We also show that, under some circumstances, coating superlens may recover subwavelength information transmitted in a relative spatial spectrum ranging from 1 to √ε₃.

In this paper, effect of two-dimensional photonic pattern on the properties of the GaAs/AlGaAs based light emitting diode (LED) is demonstrated. The interference lithography was employed to surface patterning of the GaAs/AlGaAs based LED. The active region of the LED includes a GaAs/AlGaAs triple quantum well emitting at 850 nm. Interference lithography was used for preparation of two-dimensional pattern in the upper diode layer. The prepared LED with two-dimensional patterned photonic crystal structure was then investigated by electrical and optical measurements. Prepared photonic crystal LED shows enhanced light extraction efficiency due to the more effective extraction of guiding modes, what was documented from finite difference time domain simulations as well as from L(I) measurements.

This work considers the application of Effective-Medium Approximation to the case of thin inhomogeneous layer like a layer of nanoparticles on a surface. It is shown that Effective-Medium Approximation models built for the case of bulk composites are not able to describe the optical properties on thin layers. Another approach based on the Green function formalism and accounted all interparticle interactions is proposed to construct the effective polarizability of such a layer, which can be considered as two-dimensional analogue of standard Effective-Medium Approximation for bulk media.

In this paper, the preliminary results for thin carbon-palladium (C-Pd) nanocomposites obtained by PVD/CVD method, carried out using optical methods are presented. Raman studies reveal the dominance of graphite-like structures. The optical transmittance measurement shows an exceptionally low value of the effective extinction coefficient when compared to amorphous graphite. The carbon structure porosity impact on the transmission properties of the studied layers is discussed.