This PDF file contains the front matter associated with SPIE Proceedings Volume 7392, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Straightforward extension of canonical microwave metamaterial structures to optical and IR frequency dimensions is complicated by both the size scale of the resulting structures, requiring cutting edge lithography to achieve the requisite line-widths, as well as limitations on assembly/construction into final geometry. We present a scalable fabrication approach capable of generating metamaterial structures such as split ring resonators and split wire pairs on a micron/sub-micron size scale on concave surfaces with a radius of curvature ~ SRR diameter. This talk outlines the fabrication method and modeling/theory based interpretation of the implications of curved metamaterial resonators.

We consider the optical ray dynamics in the objects formed by the media with hyperbolic dispersion, and uncover the origin of rapid transition to chaos in such systems.

We present a new way of measuring chirality, via the spectral shift of photonic band gaps in one-dimensional structures. We derive an explicit mapping of the problem of oblique incidence of circularly polarized light on a chiral one-dimensional photonic crystal with negligible index contrast to the formally equivalent problem of linearly polarized light incident on-axis on a non-chiral structure with index contrast. We derive analytical expressions for the first-order shifts of the band gaps for negligible index contrast. These are modified to give good approximations to the band gap shifts also in the case of appreciable index contrast. We believe that this may potentially be used for measuring enantiomeric excess.

3D-FDTD is used to compute the electromagnetic response of various plasmonic nanostructures. Results of computation and simulation are used to design the contact area of the photo-catalytic reactors. Novel nano-fabrication techniques are developed to implement large surface area of plasmonic nanostructures for photo-catalytic reactors. Measurement and analysis of the photo-catalytic process happened in the newly designed photo-chemical reactors clearly demonstrate better efficiency of some photo-catalytic chemical process such as the decomposition of the Methyl Orange to carbon dioxide and water.

Ideal metamaterials would consist of metal conductors only that are necessary for negative ε and μ. However, most of present-day metamaterials include dielectrics for various support functions. Overcoming dielectrics, we manufactured free-standing THz metamaterials as bi-layer chips of S-string arrays suspended by window-frames at a small gap that controls the resonance frequency. Remaining problems concerning their useful range of incidence angles and the possibility of stacking have been solved by manufacturing the first self-supported free-standing all-metal metamaterials featuring upright S-strings interconnected by metal rods. Large-area slabs show maximum magnetic coupling at normal incidence with left-handed resonances between 3.2 - 4.0 THz. Such metamaterials which we dub the meta-foil represent an ideal platform for including index-gradient optics to achieve optical functionalities like beam deflection and imaging.

Experimental investigations of the microscopic electric and in particular the magnetic near-fields in metamaterials remain highly challenging and current studies rely mostly on numerical simulations to characterize their resonant microscopic behavior. Here, we present a terahertz imaging technique, which allows us to measure the amplitude, phase and polarization of the electric near-fields in the vicinity of the resonant structures in planar metamaterials. By our approach we are able to trace the electric field vectors close to the structures after their excitation on sub-ps time scales with sub-wavelength spatial resolution. From the measured in-plane electric vector fields we are able to reconstruct the out-of-plane magnetic field vectors. As a result we obtain a comprehensive microscopic picture of the electromagnetic response in metamaterials.

Dielectric metamaterials are an attractive alternative to metallic metamaterials in order to reduce losses. Mie resonances in dielectric resonators can give rise to a resonant effective permeability or permittivity at resonance frequencies. When resonances are sufficiently enhanced permeability or permittivity can become negative. In the microwave range 2D rodshaped or 3D cylinder-shaped resonators made of high-permittivity ferroelectric material can be used to demonstrate such phenomena. In the first part we present experimental proof for TE-modes in rod resonators in the X-band (8.20- 12.40GHz) using barium strontium titanate (Ba_0.4Sr_0.6TiO₃, ε=575). In the second part we present experimental proof for modes in cylinder resonators in both the X and S-band (2.60-3.95GHz) using a commercial ceramic (ε=78). A negative index of refraction is shown in both cases.

By coupling together anisotropic electromagnetic and elastodynamic properties, piezoelectric composite materials have much to offer as multifunctional metamaterials. The linear strong-property-fluctuation theory (SPFT) may be implemented to estimate the effective constitutive parameters of certain piezoelectric composite materials in the long-wavelength regime. A key feature of the SPFT homogenization approach - which distinguishes it from other more conventional homogenization approaches-is the accommodation of higher-order characterizations of the distributional statistics of the component materials. We used the SPFT to investigate homogenized composite materials (HCMs) which arose from component materials that were generally orthorhombic mm2 piezoelectric materials and were randomly distributed as oriented ellipsoidal particles. Based on our representative numerical calculations, we concluded that: (i) the lowest-order SPFT estimates are qualitatively similar to those provided by the corresponding Mori-Tanaka homogenization formalism, but certain differences between the two estimates become more pronounced as the component particles become more eccentric in shape; and (ii) the second-order SPFT estimate provides a significant correction to the lowest-order estimate, which reflects dissipative losses due to scattering.'

We present a numerical algorithm for extracting all 36 linear constitutive parameters of a metamaterial crystal as a function of frequency and wavenumber based on driving a metamaterial with electric and magnetic charge and current. We demonstrate how spatial dispersion can result in bianisotropy in a centrosymmetric crystal. Several tests are performed on a 2D metamaterial crystal to validate these "current driven" constitutive parameters. Finally, we show how our method can be used to study spatial dispersion by studying constitutive parameters for small k.

Quantum mechanics explains the existence and properties of the chemical bond responsible for the formation of molecules from isolated atoms. In this work we study quantum states of Double Quantum Wells, DQW, formed from isolated Single Quantum Wells, SQWs, that can be considered metamaterials. Using the quantum chemistry definition of the covalent bond, we discuss molecular states in DQW as a kind of nanochemistry of metamaterials with new properties, in particular new optical properties. An important particularity of such nanochemistry, is the possible experimental control of the geometrical parameters and effective masses characterizing the semiconductor heterostructures represented by the corresponding DQW. This implies a great potential for new applications of the controlled optical properties of the metamaterials. The use of ab initio methods of intensive numerical calculations permits to obtain macroscopic optical properties of the metamaterials from the fundamental components: the spatial distribution of the atoms and molecules constituting the semiconductor layers. The metamaterial new optical properties emerge from the coexistence of many body processes at atomic and molecular level and complex quantum phenomena such as covalent-like bonds at nanometric dimensions.

The classical theory of electromagnetism is based on Maxwell's macroscopic equations, an energy postulate, a momentum postulate, and a generalized form of the Lorentz law of force. These seven postulates constitute the foundation of a complete and consistent theory, thus eliminating the need for physical models of polarization P and magnetization M - these being the distinguishing features of Maxwell's macroscopic equations. In the proposed formulation, P(r,t) and M(r,t) are arbitrary functions of space and time, their physical properties being embedded in the seven postulates of the theory. The postulates are self-consistent, comply with special relativity, and satisfy the laws of conservation of energy, linear momentum, and angular momentum. The Abraham momentum density p_EM(r,t)=E(r, t)×H(r,t)/c² emerges as the universal electromagnetic momentum that does not depend on whether the field is propagating or evanescent, and whether or not the host media are homogeneous, transparent, isotropic, linear, dispersive, magnetic, hysteretic, negative-index, etc. Any variation with time of the total electromagnetic momentum of a closed system results in a force exerted on the material media within the system in accordance with the generalized Lorentz law.

In the one-dimensional optical analog to Anderson localization, a periodically layered medium has one or more parameters randomly disordered. Such a medium can be modeled by an infinite product of 2x2 random transfer matrices with the upper Lyapunov exponent of the matrix product identified as the localization factor (inverse localization length). Furstenberg's integral formula for the Lyapunov exponent requires integration with respect to both the probability measure of the random matrices and the invariant probability measure of the direction of the vector propagated by the random matrix product. This invariant measure is difficult to find analytically, so one of several numerical techniques must be used in its calculation. Here, we focus on one of those techniques, Ulam's method, which sets up a sparse matrix of the probabilities that an entire interval of possible directions will be transferred to some other interval of directions. The left eigenvector of this sparse matrix forms the estimated invariant measure. While Ulam's method is shown to produce results as accurate as others, it suffers from long computation times. The Ulam method, along with other approaches, is demonstrated on a random Fibonacci sequence having a known answer, and on a quarter-wave stack model with discrete disorder in layer thickness.

In this work, we prepare and optically characterize novel, titanium-containing hybrid materials that can be structured three-dimensionally using two-photon polymerization. We investigate the effect on the structurability of the increase of titanium isopropoxide and methacrylic acid content in this photosensitive composite. We show that while it is possible to make transparent thin films with titanium isopropoxide molar content as high as 90%, three-dimensional structures can be made only when the titanium isopropoxide molar content is less than 50%. We measure the refractive index of different titanium isopropoxide: methacrylic acid concentrations in the composite. We show a linear increase of the composite refractive index with titanium isopropoxide concentration, while the increase of the methacrylic acid content does not it.

We describe a simple and universal technique of controlled non-covalent assembly of metallic nanorods (NRs) using self-assembled stacks of lyotropic chromonic molecules. Depending on the charge of the NRs, the chromonic stacks assemble them either end-to-end or side-by-side through anisotropic attractive forces. The anisotropically aggregated systems of NRs show pronounced changes in spectral properties as compared to those of individual NRs, with longitudinal and transverse plasmon peaks shifting accordingly to the geometry of assembly. The length of chromonic stacks is not fixed by covalent bonds and depends strongly on temperature, chromonic concentration, ionic content and pH of the solution. As a result, all these parameters can be used to control the assembly of NRs through the control of the linking agents. We also demonstrate that the process of NRs assembly can be quenched by adding a polyelectrolyte to the solution of NRs and chromonic material. The NR assemblies arrested by the polyelectrolyte can be transferred into a polymer film such as polyvinyl alcohol, preserving their structural and optical features.

The creation of electromagnetic metamaterials that will operate at THz frequencies, and into the visible frequency range, is an extremely important task that points to far-reaching medical, data storage, and processing applications. It is imperative, therefore, that these properties be associated with complex systems that can sustain both guided and surface waves in the nonlinear regime, and to offer the possibility of tunability through the addition of a gyromagnetic environment. In particular, a magneto-optic part of a metamaterial guiding structure will exert a dramatic influence because it can readily take advantage of the types of nanostructured geometries that are coming into existence. If the nonlinearity is strong, the shape of the modal fields of nonlinear guided waves changes significantly with power, as demonstrated a long time ago. The investigation of spatial and temporal solitons in double negative metamaterials is important to the future of integrated optical structures which rely upon specialized data manipulation. Some examples of strongly nonlinear waves will be given and the magnetooptic influences will be reserved for soliton management.

We review the recent experimental results from our Nonlinear Physics Center on tunability and nonlinear response of microstructured metamaterials with negative refractive index. We suggest and design new types of tunable metamaterials exhibiting either nonlinear magnetic or nonlinear electric response at microwave frequencies. By introducing a varactor diode as a nonlinear element within each resonator, we shift the frequency of either magnetic or electric resonance by changing the incident power. We also discuss a novel approach for efficient tuning of the transmission characteristics of metamaterials through a continuous adjustment of the lattice structure, the so-called structural tunability. Some of the tuning mechanisms discussed here can be suitable for scaling toward optical wavelengths with useful applications realizable in a wide frequency range.

Nano-imaging through metallic nanostructures has recently attracted lost of attention with the proposals of superlens and nanolens. The difficulties, however, are in achieving color images and magnification for the practical observation of the image. We propose a nanolens, which is made of silver nanorods arranged in stacked layered configuration that provides broad resonance for achieving color imaging, as well as it provides long-distance image transfer without significant loss. A tapered arrangement of the nanorods within the stacked layers enables magnification of image for its far field observation by usual optics.

We present a technique for subwavelength far-field focusing of light in planar non-resonant structures. The approach combines the diffraction gratings that generate high-wavevector waves and planar slabs of homogeneous anisotropic metamaterials that propagate these waves and combine them at the subwavelength focal spots. The technique has all the benefits of Fresnel lens, near-field zone plate, hyperlens, and superlens, and at the same time resolves their fundamental limitations. Several realizations of hypergratings for visible, near-IR, and mid-IR frequencies are proposed, and their performance is analyzed. Generalization of the developed approach for sub-diffractional imaging and on-chip photonics is suggested.

In this work, we present the design of a reactive screen to synthesize a desired field pattern with sub-wavelength features at visible frequencies. Following the recent theoretical developments in the field of optical nano-circuits, the screen consists of a discrete set of dielectric cells, behaving as lumped reactive elements in the visible. The spatial distribution of the cells enables the focalization of a sub-wavelength spot at a prescribed focal distance. The resolution achievable with the proposed technique depends on the electrical size of the cells and on their mutual separations. The theoretical expectations are confirmed by the numerical results, obtained through a proper full-wave simulator based on the finite integration technique. Some design examples are, finally, presented to show some of the capabilities of the proposed method.

Recently, the near-field superlens (NFSL) based on the negative permittivity (ε < 0) has been much attraction issue because of its useful application in a near-field imaging system beyond the diffraction limits. Silver in the UV region and silicon carbide in the mid-IR regime has been reported as suitable materials for the NFSL. However, these materials have the intrinsic absorption loss, which blurs the near-field image. In this research, we theoretically predict enhancement of image quality in a lossy NFSL system using the full-wave numerical approach and electrostatic approximation method. As a result, we recognized that an unmatched NFSL has better image quality compared to the traditional match NFSL.

We introduce the symmetric and asymmetric coupling between two geometry-different split-ring resonators (SRRs) with dissimilar resonance frequencies and quality factors. An additional sharp transmission peak is excited as the strong coupling occurs between a narrow subradiant resonance and a broad superradiant resonance by examining the spacing of two SRR constituents. The mechanism of such induced transparency is elucidated well by the suppression of induced currents within the SRR element with a lower quality factor. Finally, the excitation of asymmetrically coupled resonance (ACR) is further associated with remarkable confinement of electromagnetic field on nanoscale, providing a dramatically sensing performance due to its pronounced sensitivity and a characteristic of sharp bandwidth.

We discuss the optical properties metal nanoforests - a composite metamaterial in which silver nanowires are aligned inside a finite-thickness dielectric host medium. Using finite-element modelling and a self-consistent extraction of effective-medium parameters, we find that this structure can enable an effective optical diamagnetic response that is orders of magnitude stronger compared to that of naturally occurring diamagnetic materials. Our analysis reveals that there is a frequency region where the nanoforest exhibits strong diamagnetic response while simultaneously allowing for high transmission of incident electromagnetic waves. Our analysis shows that the phenomena are robust to the presence of disorder, in the occurrence of which it can still facilitate high figure-of-merit diamagnetic responses.

We will review the current status of various intrinsic definitions of negative refraction (i.e. negative phase velocity, or NPV, propagation which has been variously ascribed to counter-position of (i) the group velocity, (ii) the energy velocity, (iii) the Poynting Vector, with the wave vector of a plane wave in a medium. A key result is that simultaneously negative effective ε and μ can be achieved in a natural medium in motion. However, can this be said to result in observable phenomena? Recent progress in covariant methods has led to a more rigorous definition that is tied mathematically to what happens in the medium's rest frame. The challenge to produce a definition of NPV propagation that is not restricted to linear reference frames is also addressed. As well, progress has been made recently in clarifying the role of causality in deriving conditions for NPV propagation.

We introduce a family of materials which are homogeneous and which posses a negative index of refraction at optical frequencies. The desirable negative effect is not based on the chirality of the molecules, but rather on two other ideas (A.-G. Kussow and A. Akyurtlu, Phys. Rev. B, 78, 205202 (2008)): Firstly, there are known materials such as magnetic semiconductors (e.g. In_2-xCr_xO₃,), and 3 d transition metals (Fe, Ni), in which the high-frequency spin wave modes coexist with the plasmonic modes. The spin wave (magnon) mode is coupled with the e.m. field of the light close to the boundary of the Brillouin zone. Consequently, the spin wave mode, along with the plasmonic mode, are activated by the e.m. field of the light, with simultaneous negative permittivity and permeability responses. As a result, the material exhibits the negative refractive index effect within the frequency band close to the ferromagnetic resonance. Secondly, based on methods of Quantum Optics, we discuss the possibility of achieving the negative index of refraction in an n-type doped semiconductor. The quantum states of hydrogen-like donor atom and states of an electron in conduction band constitute a discrete-level atomic medium within the optical range. The coherent coupling of an electric dipole transition with a magnetic dipole transition leads to negative permeability and permittivity responses and ensures the negative refractive index effect. The implementation of this scheme is carried out in tin-doped indium oxide, In_2-xSn_xO₃ (ITO), and calculations show feasibility of this effect with FOM > 10.

Metamaterials building blocks, from microwave to optical range are mainly based on metal-dielectric composite. In almost all structures with true negative index (not coming from losses) two kind of meta-atoms (electric and magnetic) are mixed in order to drive simultaneously the effective permittivity and permeability to negative values and thus to obtain a negative index of refraction. In this paper we show that two coupled structures with localized plasmons modes (e.g. Cut wires or Split-Ring-Resonators) can exhibit negative refractive index by their own, by appropriately controlling the hybridization scheme of the so called plasmons modes. As a result, the metallic filling factor is drastically reduced and low losses especially at optical frequencies may allow realistic applications of metamaterials.

The differences between the resonant response of metallic and metamaterial gratings, both supporting surface polaritons, evidence the different kind of interference processes occurring between the fields radiated by the surface polariton and the fields reflected by the surface without corrugation. As in any resonance phenomenon, complementary information can be obtained by studying the associated homogeneous problem, i.e., by finding the characteristics of the electromagnetic eigenmodes supported by the corrugated interface. In this paper we solve this associated homogeneous problem, showing how a periodic corrugation affects the characteristics of surface polaritons propagating along the interface between a conventional dielectric medium and a metamaterial medium with a negative index of refraction.

In this work, we illustrate a framework that can model propagation through a dispersive, homogeneous periodic/quasiperiodic/ randomly perturbed, layer lengths in a multilayered structure of positive and negative index materials. We achieve this by using a transfer matrix-based multilayered approach. In the quasi-periodic case the layers lengths vary according to a predetermined function like a sinusoidal function for example. In the random case we use zero mean random variables as the perturbation around a nominal layer length of positive and negative index materials. We also use the trace of the transfer matrix to determine the limiting case of the transmittance when the number of periods become infinitely large, and determine the locations of the bandgaps in the multi-layered structure. This helps in reducing the calculations since only one unit cell is needed. Plane wave propagation is investigated, and aggregated transmittivity is calculated in the different cases. Finally we study wave localization in the randomly perturbed structure and compare it with the periodic case.

We theoretically demonstrate the possibility of dynamically controlling the response of metamaterials at optical frequencies using the well known phenomenon of coherent control. Our results predict a variety of effects ranging from dramatic reduction of losses associated with the resonant response of metamaterials to switchable ultraslow to superluminal propagation of pulses governed by the magnetic field of the incident wave. These effects, generic to all metamaterials having a resonant response, involve embedding the metamaterial in resonant dispersive coherent atomic/molecular media. These effects may be utilized for narrow band switching applications and detectors for radiation below predetermined cut-off frequencies.