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In this Letter, an all metallic sensor based on ε-near-zero (ENZ) metamaterials is studied both numerically and experimentally when working at microwave frequencies. To emulate an ENZ medium, a sensor is made by using a narrow hollow rectangular waveguide, working near the cutoff frequency of its fundamental TE10 mode. The performance of the sensor is systematically evaluated by placing subwavelength dielectric analytes (with different sizes and relative permittivities) within the ENZ waveguide and moving them along the propagation and transversal axes. It is experimentally demonstrated how this ENZ sensor is able to detect deeply subwavelength dielectric bodies of sizes up to 0.04λ and height 5 × 10−3 λ with high sensitivities (and the figure of merit) up to 0.05 1/RIU (∼0.6 GHz−1) and 0.6 1/RIU when considering the sensor working as a frequency- or amplitude-shift-based device, respectively. [ABSTRACT FROM AUTHOR]

Remote sensing and manipulation of quantum emitters are functionalities of significant practical importance in quantum optics. Unfortunately, these abilities are considered as fundamentally challenging in systems of inhibited spontaneous emission. The reason is intimately related to the common perception that, in order to nullify the spontaneous emission decay rate, the system has to be electromagnetically closed, meaning that all loss channels should be avoided, including radiation. However, since radiation is prohibited in these systems, far-field sensing and by reciprocity, also far-field manipulation are considered impossible. Here, we suggest a possible solution to this challenge and theoretically propose an electromagnetically open system that may exhibit a complete inhibition of spontaneous emission while supporting guiding waves. This peculiar functionality is achieved through a feedback wave mechanism that is found in parity-time-symmetric structure. The analysis is based on an exact Green's function derivation as well as full wave simulations involving a realistic design for the sake of future experimental validation. [ABSTRACT FROM AUTHOR]

Presents a study that showed the treatment of electromagnetic wave propagation and mode coupling in a chirowaveguide using the coupled-mode theory. Description of a chiral object; Background on chirowaveguide; Differential equations useful in analyzing how energy can be converted from one mode to the other inside a single chirowaveguide.

The performance of an epsilon-near zero (ENZ) plano-concave lens is experimentally demonstrated and verified at the D-band of the millimeter-waves. The lens is comprised of an array of narrow metallic waveguides near cut-off frequency, which effectively behaves as an epsilon-near-zero medium at 144 GHz. A good matching with free space is achieved by exploiting the phenomenon of energy squeezing and a clear focus with a transmission enhancement of 15.9 dB is measured. The lens shows good radiation properties with a directivity of 17.6 dBi and low cross-polar components of -34 dB. All results are supported by numerical simulations. [ABSTRACT FROM PUBLISHER]

It is known that e-near-zero (ENZ) structures may provide exciting possibilities for light-matter interaction, including the phenomenon of supercoupling, i.e., channeling of wave energy through ultranarrow conduits connecting two waveguides. Here, we extend this concept to the surface waves using structures with effective ENZ properties, exploring how surface waves can tunnel through such structures with essentially no reflection, even in the presence of sharp bends. Such ENZ metastructures support tunneling of waves with longitudinal wave numbers near zero. The surface waves may include examples of transverse electric (TE) surface waves along the grounded dielectric slabs (e.g., in the microwave regime) and TE surface-plasmon polariton waves along the negative-permeability interfaces. The ENZ metastructures can transfer the surface wave energy from one side to another by an anomalous squeezing effect, which is effectively independent of the length and the shape of the ENZ metastructures. The interaction of electromagnetic waves with such systems offers exciting possibilities for the design of flat photonic devices and components. [ABSTRACT FROM AUTHOR]

We present an analytical model and practical design tools to realize cylindrically-symmetric compact antennas based on the anomalous transmission properties of \varepsilon-near-zero (ENZ) ultranarrow radial channels. The flexibility and exotic propagation properties in ENZ metamaterial channels are exploited here to tune and match cylindrically-symmetric antennas, without the need of complex external matching networks, in order to realize exciting antenna designs in terms of size, complexity and efficiency. We first model a homogenized Drude dispersive ENZ metamaterial channel to feed a radial parallel-plate waveguide; next we suggest a practical realization of this channel by using radial fins; eventually, we apply the obtained design formulas to realize single- and multi-band cylindrical antennas with a wide tunability range. The designed antennas may operate in the ultra-high frequency (UHF) band and may be realistically tuned over a large bandwidth. We envision applications in frequency-hopping, multi-band, compact, omnidirectional antennas. [ABSTRACT FROM PUBLISHER]

We apply the optical nanocircuit concepts to model and design optical nanofilters in realistic plasmonic waveguides of different nature, including strips and groove waveguides. The nanocircuit elements are designed to fit the waveguide geometry, and its equivalent impedance is analytically calculated by substituting the role of the conduction current with displacement current. The effect of plasmonic waveguide walls is rigorously modeled in terms of an extra nanocircuit loading that is included in our model. We show via numerical results that the nanocircuit approach may be effectively applied to the design of nanofilters, analogous to familiar concepts at radio-frequencies. [ABSTRACT FROM PUBLISHER]

We theoretically explore the possibility of reducing propagation loss in a metal-insulator-metal (MIM) waveguide, using mode combinations to achieve wall-avoiding field distributions along a certain propagation length. We present analytical results for several waveguides showing notable loss reduction, and we discuss the trade-offs between low loss and high confinement present in this technique. [ABSTRACT FROM AUTHOR]

We propose the use of metamaterial-inspired ultranarrow channels at cutoff to realize an interesting matching between a coaxial antenna and a waveguide. The anomalous properties of a channel at cutoff, analogous to those of zero permittivity materials, allow a simple matching design, valid for arbitrary waveguides, with large degrees of freedom in terms of geometry, length and possible bending of the connecting channel. Moreover, the static-like properties of the channel allow such matching, independent of the relative position of the antenna and possible bending and abruptions along the channel. [ABSTRACT FROM AUTHOR]

Following our previous work, here an artificial magnetic conducting (AMC) surface, comprised of Hilbert and/or Peano space-filling curve inclusions is utilized as a thin electromagnetic absorber. Numerical results are presented to show the effects of the incident angle, conducting strip widths and substrate thicknesses on the absorbing properties of such surfaces. The performance of a fabricated thin absorber in reducing the RCS of a conducting plate is demonstrated through measurement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 785–790, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24186 [ABSTRACT FROM AUTHOR]

A method of realizing nanoantenna systems at optical frequencies is suggested wherein a plasmonic nanowire is placed near a slab waveguide operating near the plasmonic resonant frequency of the nanowire. The polarizability of a nano-sized concentric cylindrical structure with the core made of an ordinary dielectrics and the shell made of a plasmonic material is calculated using Mie scattering theory. When such a core-shell nanowire is placed near a slab waveguide, the transverse magnetic (TM) surface wave guided by the waveguide can interact with the nanowire, and thus part of its energy is scattered into the open space. By reciprocity, under TM wave incidence, the induced dipole on the nanowire will launch a guided mode in the slab waveguide, thus converting part of the incident energy into the guided mode energy. A rigorous analytical treatment of the problem using the Green function of a dipole near a planar slab waveguide is developed, and the properties of such an optical antenna system are studied in detail. The finite element method is also utilized to demonstrate the idea directly. [ABSTRACT FROM AUTHOR]

The potential use of metamaterial planar bilayers for synthesizing compact subwavelength leaky-wave radiators in the microwave regime is analyzed in detail. In particular, the possibility of pairing "complementary" metamaterials in order to reduce the dimensions of microwave components is explored for the leaky-wave operation of an open waveguide consisting of a grounded pair of planar layers. In connection with our similar findings in other setups employing such complementary pairings, here we show how the compact resonance at the interface between "negative" and "positive" materials may also be properly exploited in this context. Choosing materials with low constitutive parameters, moreover, shows to be effective for enhancing the directivity of these components. We explore in detail the notable guidance and radiation properties of the anomalous natural modes supported by these bilayered structures, giving some physical insights into the anomalous phenomenon and considering the possible limitations in some realistic setups. [ABSTRACT FROM AUTHOR]

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Presents the results of a theoretical analysis for guided modes in parallel-plate waveguides filled with pairs of parallel layers. Salient properties of the guided modes; Ways in which materials and their parameters are chosen to be paired; Contrast with those of the guided modes in conventional waveguides; Physical insights and intuitive justifications for the mathematical findings.

Confining and controlling electromagnetic energy typically involves a highly resonant phenomenon, especially when subwavelength confinement is desired. Here, we present a class of nonresonant, self-dual planar metastructures capable of protected energy transmission from one side to the other, through arbitrarily narrow apertures. It is shown that the transmission is in the form of matched propagating modes and is independent of the thickness and specific composition of the surface. We analytically prove that the self-dual condition is sufficient to guarantee 100% transmission that is robust to the presence of discontinuities along the propagation path. The results are confirmed numerically through study of various scenarios. The operation is broadband and subject only to the bandwidth of the constituent materials. The polarization of the internal field can also be independently controlled with respect to the incident one. Our structures are promising for applications in sensing, particle trapping, near-field imaging, and wide scan antenna arrays. [ABSTRACT FROM AUTHOR]

Near-zero-index (NZI) media, a medium with near zero permittivity and/or permeability, exhibits unique wave phenomena and exciting potential for multiple applications. However, previous proof-of-concept realizations of NZI media based on bulky and expensive platforms are not easily compatible with low-cost and miniaturization demands. Here, we propose the method of substrate-integrated (SI) photonic doping, enabling the implementation of NZI media within a printed circuit board (PCB) integrated design. Additionally, the profile of the NZI device is reduced by half by using symmetries. We validate the concept experimentally by demonstrating NZI supercoupling in straight and curve substrate integrated waveguides, also validating properties of position-independent photonic doping, zero-phase advance and finite group delay. Based on this platform, we propose design of three NZI devices: a high-sensitivity dielectric sensor, an efficient acousto-microwave modulator, and an arbitrarily-curved 'electric fiber'. Our results represent an important step forward in the development of NZI technologies for microwave/terahertz applications. Here, the authors demonstrate substrate-integrated photonic doping, enabling the implementation of near-zero-index media within a printed circuit board integrated design. They illustrate the potential by designing and numerically demonstrating a dielectric sensor, an acousto-microwave modulator and a flexible transmission line. [ABSTRACT FROM AUTHOR]

Here we theoretically predict and experimentally verify that permeability μ-near-zero (MNZ) materials give the opportunity to supercouple waveguides with highly mismatched cross sections. Rather distinct from the supercoupling provided by permittivity-near-zero materials we discovered several years ago, the MNZ supercoupling can take place when the transition channel cross section is much wider than that of the input and output waveguides. We develop a simple analytical model that captures the physical mechanisms that enable this remarkable effect. The MNZ supercoupling effect is experimentally verified with rectangular waveguide technology by mimicking the μ-near-zero response with the help of cylindrical split ring resonators. [ABSTRACT FROM AUTHOR]

We introduce the concept of metamaterial analog computing, based on suitably designed metamaterial blocks that can perform mathematical operations (such as spatial differentiation, integration, or convolution) on the profile of an impinging wave as it propagates through these blocks. Two approaches are presented to achieve such functionality: (i) subwavelength structured metascreens combined with graded-index waveguides and (ii) multilayered slabs designed to achieve a desired spatial Green's function. Both techniques offer the possibility of miniaturized, potentially integrable, wave-based computing systems that are thinner than conventional lens-based optical signal and data processors by several orders of magnitude. [ABSTRACT FROM AUTHOR]

We fabricate and characterize a metal-dielectric nanostructure with an effective refractive index n = 0 in the visible spectral range. Light is excited in the material at deep subwavelength resolution by a 30-keV electron beam. From the measured spatially and angle-resolved emission patterns, a vanishing phase advance, corresponding to an effective € = 0 and n = 0, is directly observed at the cutoff frequency. The wavelength at which this condition is observed can be tuned over the entire visible or near-infrared spectral range by varying the waveguide width. This n = 0 plasmonic nanostructure may serve as a new building block in nanoscale optical integrated circuits and to control spontaneous emission as experimentally demonstrated by the strongly enhanced radiative optical density of states over the entire n = 0 structure. [ABSTRACT FROM AUTHOR]