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Full-Text Articles in Engineering
Circuit Elements At Optical Frequencies: Nanoinductors, Nanocapacitors, And Nanoresistors, Nader Engheta, Alessandro Salandrino, Andrea Alù
Circuit Elements At Optical Frequencies: Nanoinductors, Nanocapacitors, And Nanoresistors, Nader Engheta, Alessandro Salandrino, Andrea Alù
Andrea Alù
We present the concept of circuit nanoelements in the optical domain using plasmonic and nonplasmonic nanoparticles. Three basic circuit elements, i.e., nanoinductors, nanocapacitors, and nanoresistors, are discussed in terms of small nanostructures with different material properties. Coupled nanoscale circuits and parallel and series combinations are also envisioned, which may provide road maps for the synthesis of more complex circuits in the IR and visible bands. Ideas for the optical implementation of right-handed and left-handed nanotransmission lines are also forecasted.
Pairing An Epsilon-Negative Slab With A Mu-Negative Slab: Resonance, Tunneling And Transparency, Andrea Alù, Nader Engheta
Pairing An Epsilon-Negative Slab With A Mu-Negative Slab: Resonance, Tunneling And Transparency, Andrea Alù, Nader Engheta
Andrea Alù
Here, we analyze the transverse-magnetic (TM) wave interaction with a pair of slabs, one being an epsilon-negative (ENG) layer in which the real part of permittivity is assumed to be negative while its permeability has positive real part, and the other being a mu-negative (MNG) layer that has the real part of its permeability negative but its permittivity has positive real part. Although wave interaction with each slab by itself has predictable features, we show that the juxtaposition and pairing of such ENG and MNG slabs may, under certain conditions, lead to some unusual features, such as resonance, complete tunneling, …
Theory And Simulations Of A Conformal Omni-Directional Sub-Wavelength Metamaterial Leaky-Wave Antenna, Andrea Alù, Filiberto Bilotti, Nader Engheta, Lucio Vegni
Theory And Simulations Of A Conformal Omni-Directional Sub-Wavelength Metamaterial Leaky-Wave Antenna, Andrea Alù, Filiberto Bilotti, Nader Engheta, Lucio Vegni
Andrea Alù
The detailed theory of a single subwavelength conformal radiator that exploits the resonant properties of thin cylindrical metamaterial shells supporting leaky waves is presented. It is shown and reviewed analytically and numerically how a circularly symmetric resonant leaky mode may be supported by a properly designed subwavelength homogenous cylindrical shell of low negative permittivity. Some physical insights are provided and numerical simulations with a feed point, considering also the finiteness of the antenna in the longitudinal direction, are presented and discussed. Moreover, possibilities and limitations of a practical realization of this setup are mentioned, considering in details the possible anisotropies …
Achieving Transparency With Plasmonic And Metamaterial Coatings, Andrea Alù, Nader Engheta
Achieving Transparency With Plasmonic And Metamaterial Coatings, Andrea Alù, Nader Engheta
Andrea Alù
The possibility of using plasmonic and metamaterial covers to drastically reduce the total scattering cross section of spherical and cylindrical objects is discussed. While it is intuitively expected that increasing the physical size of an object may lead to an increase in its overall scattering cross section, here we see how a proper design of these lossless metamaterial covers near their plasma resonance may induce a dramatic drop in the scattering cross section, making these objects nearly “invisible” or “transparent” to an outside observer—a phenomenon with obvious applications for low-observability and noninvasive probe design. Physical insights into this phenomenon and …
Guided Modes In A Waveguide Filled With A Pair Of Single-Negative (Sng), Double-Negative (Dng), And/Or Double-Positive (Dps) Layers, Andrea Alù, Nader Engheta
Guided Modes In A Waveguide Filled With A Pair Of Single-Negative (Sng), Double-Negative (Dng), And/Or Double-Positive (Dps) Layers, Andrea Alù, Nader Engheta
Andrea Alù
Here we present the results of our theoretical analysis for guided modes in parallel-plate waveguides filled with pairs of parallel layers made of any two of the following materials: 1) a material with negative real permittivity, but positive real permeability (epsilon-negative); 2) a material with negative real permeability, but positive real permittivity (mu-negative); 3) a material with both negative real permittivity and permeability (double-negative); and 4) a conventional material with both positive real permittivity and permeability (double-positive) in a given range of frequency. Salient properties of these guided modes are studied in terms of how these materials and their parameters …