This PDF file contains the front matter associated with SPIE Proceedings Volume 7711, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

The creation of electromagnetic metamaterials is an important activity. The latter should anticipate the kind of applications in which unique metamaterial behaviour can appear. This paper addresses nonlinear wave phenomena in both the strongly and the weakly nonlinear regimes. It inevitably involves novel nonlinear guided waves and solitonic beam activities. In this context, some magnetooptic control is introduced. In addition, the kind of structural complexity that can lead to trapped rainbows will be briefly examined. Finally, some aspects are made of vortex control in a diffraction-managed metamaterial is presented.

Exploiting the concept of internal surface plasmon polariton (I-SPP) resonances, which appear at non-single metallic film stacks, we have designed a metamaterial showing a negative effective refractive index within a large bandwidth. The designed structure consists of an arrangement of several fishnet layers. By properly adjusting the lattice constant and the thickness of the dielectric slab of the fishnet, an I-SPP mode can be excited at a certain frequency giving rise to a negative effective refractive index. Thus, the combination of several fishnet layers, each one of them configured to excite an I-SPP at a different frequency, enables us to extend the bandwidth at which a negative effective refractive index is achieved, as long as the selected resonances are close enough. Specifically, from a subwavelength chain of two fishnet layers, the retrieved effective parameters show a negative index behavior in a frequency span of about 44THz centered at 210THz, owing to the fact that an I-SPP is excited in each fishnet layer at slightly different frequencies.

Optical chirality is reported in a silver thin film with an ordered array of subwavelength Z-shaped apertures. Normal incidence transmission of right-hand circular polarized light through the planar chiral nanostructure is found to be sensitive to the direction of the light propagation resembling well-known circular dichroism phenomenon. The relative transmission difference is increased in the spectral vicinity of the surface plasmon resonances and reaches 0.11. The azimuthal dependences of elliptization of light state are shown to depend upon the direction of light propagation and this effect is also addressed to optical chirality of the specimen. It is experimentally demonstrated that the metamaterial could be substituted for anisotropic lossy medium whose tensors of real and imaginary parts of permittivity are diagonalized in different Cartesian coordinate systems. The angle between these systems is experimentally found to reach 10° in the site of plasmon resonances.

We report on simulations of the imaging properties of metal-dielectric layered flat lenses and their tolerance to experimental inaccuracies of layers thickness and errors of permittivity values of materials. The multilayer structure consisting of silver and amorphous TiO2 is optimised in terms of the transmission efficiency and FWHM of the point spread function. Standard deviation of thickness for both metals and dielectrics layers, accepted in simulations, are twice bigger than actual fabrication parameters determined with quartz crystal microbalance. The errors of material permittivity measurements are taken from literature. Numerical investigation of imaging properties of the lenses is performed with the transfer matrix method. The quality of surfaces of silica substrate, titanium oxide, gold, and silver layers is measured with atomic force microscope.

In a numerical experiment, we optimise performance of plasmonic lenses with different structures of single metal nanolayers. The nanolenses, either with double sided grooved or with slits act like classical, high-numerical aperture, refractive objectives. Their focal regions are well defined and different from those of diffractive optical elements. The narrowest rotationally symmetric foci are achieved for a Laguerre-Gauss intensity profile with radial polarization. The highest transmission reaching 80% is achieved for high slit width-to-lattice constant ratios when light is waveguided in annular slits. In grooved and continuous metal lenses transmission reaches 30% due to resonant tunnelling of plasmons. Location of slit/groove edges, which act as sources of spherical waves, and light intensity at them decides on interference of radial and longitudinal electric field components in focal region. Proper choice of lattice constants and surface structure allows for focal length several times larger than the free space light wavelength. All simulations are made using body-of-revolution finite difference time domain method and Drude model parameters of silver. In simulations we accept parameters of the nanolenses which are possible to fabricate with technical equipment available to us.

This paper presents the development of heterodyne receiver configurations based on EBG technology. The basic required building blocks, waveguides and cavities are first described. A subhamonic EBG receiver design is finally presented.

This work presents a sensitivity analysis for the resonance frequency and bandwidth of dielectric supported Split Ring Resonator (SRR) metmaterial in THz frequency. The different designed parameters have been considered and their parametric sensitivities on resonance frequency and on bandwidth have been analyzed. The finite integral technique is used to simulate the structure and the numerical techniques are used to obtain the resonance frequency and bandwidth sensitivities as a function of the designed parameters. The analysis for sensitivity of the scattering parameters of metamaterial is especially very important in THz frequency range. The resonance frequency and the bandwidth are the main characteristics of a resonator Frequency Selective Surface (FSS). The development of FSS in mm-wave frequency range can be simplified by the knowledge of the sensitivity of their main characteristics as a function of the considered physical parameters. The FSS structure considered in this section is the square split ring resonator with copper strip lines backed by Roger 4003 C dielectric substrate. The FSS structure is simulated by using CST Microwave Studio transient solver. The resonance frequency and the bandwidth sensitivities as function structural parameters of FSS are obtained by using the simulation data. In this analysis, normal incident TE modes are considered.

The concept of metamaterials (MTMs) is acknowledged for providing new horizons for controlling electromagnetic radiations thus their use in frequency ranges otherwise difficult to manage (e.g. THz radiation) broadens our possibility to better understand our world as well as opens the path for new applications. THz radiation can be employed for various purposes, among them the study of vibrations in biological molecules, motion of electrons in semiconductors and propagation of acoustic shock waves in crystals. We propose here a new THz fractal MTM design that shows very high transmission in the desired frequency range as well as a clear differentiation between one polarisation and another. Based on theoretical predictions we fabricated and measured a fractal based THz metamaterial that shows more than 60% field transmission at around 1THz for TE polarized light while the TM waves have almost 80% field transmission peak at 0.6THz. One of the main characteristics of this design is its tunability by design: by simply changing the length of the fractal elements one can choose the operating frequency window. The modelling, fabrication and characterisation results will be presented in this paper. Due to the long wavelength of THz radiation, the resolution requirements for fabrication of metamaterials are within the optical lithography range. However, the high aspect ratio of such structures as well as the substrate thickness pose challenges in the fabrication process. The measurements were made using terahertz time domain spectroscopy (THz-TDS) that allows us to obtain both the amplitude and phase of the transmission function. The experimental results are in very good agreement with theoretical calculations based on finite-difference time-domain simulations.

The storage of light is of crucial importance for applications involving optical data processing and certain quantum-optical devices, where it can be used to control the rate of spontaneous emission of light sources. Nowadays, light can be confined using optical microresonators or stopped-light techniques. Two important figures of merit determine the quality of these devices: the quality factor Q and the mode volume V, respectively quantifying the temporal and spatial confinement of light. Most applications require small mode volumes in combination with high quality factors. However, due to the wavelike nature of light, it is generally admitted that it is impossible to store light in a volume with subwavelength dimensions in combination with a high quality factor. In this contribution, we overcome this fundamental limitation by designing an optical cavity based on a transformation-optical approach [Ginis et al., arXiv: 0911.4216v1].

In this paper, we develop a method to homogenize split-ring arrays in the frequency domain. The expected resonance and negative permeability are obtained via numerical simulations with the finite elements method. A subtle modelization of the split-ring with a closed ring pemits us to avoid meshing the small split, while maintaining the resonant behaviour of this metamaterial. Therefore, our homogenization technique simulates these metamaterials with a minimal computational cost. Simulations were made for several ring orientations, dimensions and shapes.

We investigate the application of a metamaterial that is formed by the sparse distribution of spiral resonators as an optical transformation medium is in order to achieve electromagnetic cloaking. The well-known Clausius-Mossotti formula relates the microscopic polarizability of a single resonant particle to the macroscopic permittivity and permeability of the effective medium. By virtue of transformation optics, the permittivity and permeability of the medium, in turn, can be designed according to a coordinate transformation that maps a certain region of space to its surrounding. As a result, the mapped region can be cloaked from electromagnetic waves. In this study, the spirals are optimized to exhibit equal permittivity and permeability response so that the cloak formed by these spirals will work for both the TE and TM polarizations. An experimental setup is developed to visualize the steady state propagation of electromagnetic waves within a parallel plate waveguide including the cloaking structure. The measured and simulated electromagnetic field image indicates that the forward scattering of a metal cylinder is significantly reduced when placed within the cloak.

The response of metallic split ring resonators (SRRs) scales linearly with their dimensions. At higher frequencies, metals do not behave like perfect conductors but display properties characterized by the Drude model. In this paper we compare the responses of nano-sized gold-based SRRs at near infra-red wavelengths. Deposition of gold SRRs onto dielectric substrates typically involves the use of an additional adhesion layer. We have employed the commonly used metal titanium (Ti) to provide an adhesive layer for sticking gold SRRs to silicon substrates - and have investigated the effect of this adhesion layer on the overall response of these gold SRRs. Both experimental and theoretical results show that even a two nm thick titanium adhesion layer can shift the overall SRR response by 20 nm.

Meta-foils are all-metal free-standing electromagnetic metamaterials based on interconnected S-string architecture. They provide a versatile applications' platform. Lacking any substrate or embedding matrix, they feature arrays of parallel upright S-strings with each string longitudinally shifted by half an S compared to its neighbour to form capacitance-inductance loops. Geometric parameters include length a, width b, thickness t, and height h of an S, the gap between adjacent S-strings d, and the periodicity p of the interconnecting lines. Equidistant strings at p=1 form a 1SE meta-foil. Grouped in pairs of gap d, exhibiting a gap d_p between pairs, they are named 2SP. Geometric parameters a, b, t, h, d, d_p, pS(E or P) and materials' properties like electric conductivity, Young's modulus, thermal expansion coefficient, and heat capacity determine the electromagnetic, mechanical, and thermal properties of meta-foils including the spectral dependence of resonance frequencies, refractive index, transmission, reflection, and bending. We show how the frequency and transmission of left-handed pass-bands depend on a, p, and d_p, the pSP geometry exhibiting higher resonance frequency and transmission. Equivalent circuit considerations serve to explain physical reasons. We also demonstrate mechanical behavior versus p and d_p justifying the design of a cylindrical hyperlens depending on bent meta-foils.

Colloidal chemistry strategies are mature techniques, now able to provide highly processable nanocrystals (NCs) soluble in a variety solvents, possessing an adjustable organic interface, for obtaining assembled structures. Indeed the NCs can be organized in superstructures by means of spontaneous assembly, in order to bridge the gap between nanoand mesoscale. In self assembly procedures, the organization is driven by the intrinsic information coded into the building blocks, namely size, shape and surface chemistry. The distinct properties of the nanometer-scale "buildingblocks" can be thus harnessed in assemblies presenting new collective properties, which can be further engineered by controlling inter-particle spacing and by material processing. Self assembly approaches of colloidal NCs can effectively exploit the solvent evaporation to form closely packed superlattices, since collective interaction energy can overcome the entropy loss due to ordering. The control on the NC characteristics is then crucial for the achievement of well controlled superstructures, with long range order and stability, being the individual NCs considered as "artificial atoms" in such superlattice structures. In this perspective the emerging concept of NC based metamaterials, that is a material with properties occurring from the controlled positioning of the different interacting NCs in an assembly, arise.

We review recent theoretical and experimental in progress in the realisation of slow and stopped light by the 'trapped rainbow' principle in optical metamaterials featuring negative electromagnetic parameters (permittivity/permeability and/or refractive index). We explain how and why these structures can enable complete stopping of light even in the presence of disorder and, simultaneously, dissipative losses. Using full-wave numerical simulations we show that the incorporation of thin layers made of an active medium adjacently to the core layer of a negative-refractive-index waveguide can completely remove dissipative losses - in a slow-light regime where the effective index of the guided wave is negative.

The excitation and transfer of evanescent electromagnetic waves appears as key challenge for the realization of optical imaging devices with super resolution. In this process surface plasmon polaritons (SPP) overtake the role as indispensable mediators between source fields and propagating fields. Therefore, the interaction between SPPs and the vacuum field in a double meander structure (DMS) is investigated. The occurrence of Fabry-Pérot (FP) modes within such a cavity and the SPP modes of the meander structure is analyzed to understand the interaction of both mode systems in the combined double meander structure. We show that the known Fano-type passband of single meander structures keeps its dominant role in the DMS and demonstrate the frequency selective role of meander mirrors within this meander cavity. The meander geometry determined passband frequency position also controls nearly solely the passband of the DMS. For far field superlenses (FSL) the energy transfer at low loss over practically arbitrary distances inside the structure is a key property. A resonant amplitude transfer can be obtained between resonantly coupled meander surfaces for unlimited distances in practical cases. This property enables a controlled transformation of evanescent modes to traveling wave modes of higher diffraction order useful for superlens operation.

By introducing both cavity mode and plasmonic resonance simultaneously in the designed sandwiched metamaterials, we present a scalable bandpass filter to demonstrate ultra-wide bandwidth, excellent efficiency and sharp band-edge transition. Our results show that this bandpass filter possess ultra-wide bandwidth (UWB) of 20 GHz centered at 60.5 GHz, with almost zero reflectance (0.0042) and present transitions within 0.6 GHz from -3dB to -20dB for upper and lower transmittance band-edge transition. Such an UWB bandpass filter is applicable for the commercialized unlicensed 60 GHz spectrum with a bandwidth exceeding 9 GHz, an unanswerable question for conventional passive bandpass filters to possess wide bandwidth and high quality factor simultaneously.

In this paper, we investigate the capacitance tuning of nanoscale split-ring resonators. Based on a simple LC circuit model (LC-model), we derive an expression where the inductance is proportional to the area while the capacitance reflects the aspect ratio of the slit. The resonance frequency may be tuned by the slit aspect ratio leaving the area, the lattice constant Λ, and nearest-neighbor couplings in periodic split-ring resonator structures invariant. Experimental data as well as numerical simulation data, verify the predictions of the simple LC-model.

Recently, we have discussed anchoring forces and the electric field as new control parameters for negative- positive refraction index tuning in nanosphere dispersed nematic liquid crystal (NDLC). The present study is focused on calculation of the amplitude modulation of the refractive index caused by amplitude variation of anchoring forces and spatial modulation of anchoring forces. Preliminary results indicate that, similarly to case studied earlier,1 refractive index amplitude modulation can be significantly larger as compared with a conventional liquid crystal (LC) system. The inhomogeneous molecular order in nematic liquid crystal (NLC) cells is modelled using Monte Carlo simulations with the Lebwohl-Lasher effective Hamiltonian with the Rapini- Papoular term for anchoring forces.

We discuss a novel tuning method based on continuous adjustment of metamaterial lattice parameters. This method provides for remarkable tuning of transmission characteristics through a subtle displacement of metamaterial layers. While the effective medium theory predicts correctly the general tuning characteristics, it turns out that the particular tuning pattern is determined by the peculiarities of near-field interaction between the metamaterial elements. We describe the modes of this interaction and provide qualitative explanations to the performance observed numerically and experimentally.

We report on the fabrication of a metal-dielectric composite material with tunable optical properties. The developed fabrication method relies on simultaneous DC sputtering of a metal and a suitable dielectric, creating an isotropic material with optical properties that can be controllably varied over a wide range of wavelengths. Currently the research is focusing on a combination of Ag and ZnO that is suitable for applications at the visible and telecommunication frequencies. The material combination is well suited for the deposition method chosen, and physical characterizations using AFM and SEM measurements show that the mixture forms homogeneous films with low surface roughness. In order to test the validity of this approach films are deposited with a variety of deposition parameters, focusing mainly on the relative deposition rates basically controlling the filling factor. Optical properties found from experiments using spectroscopic ellipsometry as well as farfield reflection-transmission measurements are compared to those predicted by the effective medium theory.

We report that in the absence of electric dipole contributions, upon azimuthal sample rotation, the corresponding SHG response was found to be chiral, i.e. it shows the presence of asymmetries with a sense of rotation (lack of mirror symmetry). It was found that this sense of rotation reverses with the handedness configuration (G and mirror-G, see Fig. 1). While it is apparent that the property originates in local field enhancements of electric and/or magnetic multipoles, its explanation invites further theoretical research.

The polarisation dependent optical properties of silver nanowire arrays are investigated by angular resolved transmission measurements. The corresponding spectra show clear Fabry-Perot oscillations, which exhibit an unusual shift towards longer wavelengths for the extraordinary waves. From the peak shift both principal dielectric functions of the metamaterial are determined and compared with effective medium theories. Furthermore the equifrequency contours in wave vector diagrams were mapped from the experimental data and compared with theoretical plots confirming the hypberbolic dispersion relation for TM polarised waves.

We report a new near-field Raman imaging technique by trapping and scanning a dielectric microsphere over a sample surface in water. This method has a few critical advantages over both aperture and apertureless near-field Raman techniques, such as strong near-field signal, high reproducibility, high resolution and cheap cost. In this method, the laser is focused to a spot smaller than diffraction limit and only the near-field signal is collected. Using this method, we have achieved spatial resolution of 80 nm. This spatial resolution is extremely useful and powerful for a wide range of applications such as the characterization of nanostructures and nano devices. We show the capability of our technique using a series of nanometer sized samples, e.g. device sample with 45 nm poly-Si gates with SiGe stressors, Au nanopatterns and Au nanobowl structures. Besides of the achievement of high resolution, our near-field technique also provides the opportunity to explore the near-field optical response of surface plasmons of metal nanostructures that cannot be attained by far-field spectroscopy.

Recent research on second-harmonic generation in left-handed materials has shown a light localization mechanism that originates from an all-angle phase-matching condition between counter-propagating electromagnetic modes at fundamental and double frequencies. This phenomenon opens the route for the design of second-harmonic lenses. In this paper, we recall the essential nonlinear properties needed to generate second harmonic images of linear objects. We show that this approach enable one to realize SH images of objects placed inside or outside the nonlinear lens. In the case of an external source, two distinct devices are proposed: a double lens configuration which enables to image objects between symmetric metamaterial slabs, and a single lens case characterized by an impedance mismatched interface. The versatility of these SH lenses opens new routes for the second harmonic imaging technics since they are able to produce SH images from linear objects.

Single split-ring resonators has a great interest due to their refractive index facility. In this paper we provide a comprehensive study, supported with experimental data, that addresses the effect of the type of the substrate and the geometric parameters on the resonant frequency and the quality of the design. The measurements are carried out using quasi-optical technique in mm-wave frequency range. We also provide recommendations concerning the main factors that should be considered in designing split open ring resonators at mm-wave frequency range.

The conventional metamaterials require both negative permittivity (ε) and negative permeability (μ), to achieve negative refraction. Chiral metamaterial is a new class of metamaterials offering a simpler route to negative refraction. In this paper, we review the history of metamaterials and the developments on chiral metamaterials. We study the wave propagation properties in chiral metamaterials and show that negative refraction can be realized in chiral metamaterials with a strong chirality, with neither permittivity (ε) nor permeability (μ) negative required. We have developed a retrieval procedure, adopting a uniaxial bi-isotropic model to calculate the effective parameters such as of the chiral metamaterials. In this paper we study the anomalous refraction at the boundary of a metamaterial medium with strong chirality. The fact that for a time-harmonic monochromatic plane wave the direction of the Poynting vector is antiparallel with the direction of phase velocity, leads to exciting features that can be advantageous in the design of novel devices and components at microwaves frequencies. This work is concerned with the propagation of electromagnetic waves in isotropic chiral media and with the effects produced by a plane boundary between two such media. In analogy with the phenomena of reflection and refraction of plane electromagnetic waves in ordinary dielectrics, the kinematical and dynamical aspects of these phenomena are studied, in situations such as the intensity of the various wave components and the change in the polarization of the wave, as it crosses the boundary. This research might be applied to the design of very high frequency microwaves and non symmetrical transmission lines. In our work, the design, numerical calculations and experimental measurements of chiral metamaterials is introduced. Strong chiral behaviours such as optical activity and circular dichroism are observed and negative refraction is obtained for circularly polarized waves in these chiral metamaterials. We show that 3D isotropic chiral metamaterials can eventually be realized.

We prove theoretically that it is possible to build embedded reflectionless squeezers/expanders using transformation optics. We illustrate the potential of this finding by proposing an application in which the squeezer is a key element: an ultra-short perfect coupler for high-index nanophotonic waveguides.

We study the propagation of light through silver-dielectric layered structures operating in the canalization regime. These structures have an extremely large value of the effective permittivity in the propagation direction. Therefore they are able to couple a broad spectrum of incident spatial frequencies, including evanescent waves, into propagating modes. As a result, subwavelength resolution at the back interface of the structure is observed. We consider multilayers made of silver and several dielectric materials, namely TiO₂, SrTiO₃ and GaP. We optimise the multilayers geometry in order to obtain the best resolution accompanied with a large value of the effective skin depth. We use the full width at half-maximum (FWHM) of the point spread function to measure the resolution. The effective skin depth is calculated both approximately based on the effective medium model and rigorously by analysing the amplitude decay rate in an infinite periodic layered structure.