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Experimental Verification Of Epsilon-Near-Zero Metamaterial Coupling And Energy Squeezing Using A Microwave Waveguide, Brian Edwards, Andrea Alù, Michael Young, Mário Silveirinha, Nader Engheta Sep 2008

Experimental Verification Of Epsilon-Near-Zero Metamaterial Coupling And Energy Squeezing Using A Microwave Waveguide, Brian Edwards, Andrea Alù, Michael Young, Mário Silveirinha, Nader Engheta

Nader Engheta

Utilizing a microwave setup, we experimentally verify our recently developed theory of energy squeezing and tunneling [Phys. Rev. Lett. 97, 157403 (2006)] through an ultranarrow waveguide channel that mimics zero-permittivity properties. Exploiting the infinite phase velocity supported by a waveguide transition section at cutoff, we test our theory of tunneling in this zero-permittivity region without use of resonant inclusions. This "supercoupling" is shown to have unique anomalous properties: an almost uniform phase along the narrow channel and weak dependence over its geometry.


Higher-Order Resonant Power Flow Inside And Around Superdirective Plasmonic Nanoparticles, Andrea Alù, Nader Engheta Sep 2008

Higher-Order Resonant Power Flow Inside And Around Superdirective Plasmonic Nanoparticles, Andrea Alù, Nader Engheta

Nader Engheta

The optical power flow around a plasmonic particle has been a topic of research interest over the years [see e.g., C. F. Bohren, Am. J. Phys. 51, 323 (1983); V. A. Bashevoy, V. A. Federov, and N. I. Zheludev, Optics Express, 13, 8372 (2005)]. Here we revisit this problem with an emphasis on higher-order resonances, and we present the theoretical results of our analysis for such power flow distribution for plasmonic nanoparticles at their multipolar resonances. Results for the second and third orders of resonances show optical power flow patterns that are significantly different from that of the first-order resonance …


Anomalies Of Sub-Diffractive Guided-Wave Propagation Along Metamaterial Nanocomponents, Andrea Alù, Nader Engheta Sep 2008

Anomalies Of Sub-Diffractive Guided-Wave Propagation Along Metamaterial Nanocomponents, Andrea Alù, Nader Engheta

Nader Engheta

We describe our recent results on some of the anomalous propagation properties of subdiffractive guided modes along plasmonic or metamaterial cylindrical waveguides with core-shell structures, with particular attention to the design of optical subwavelength nanodevices. In our analysis, we compare and contrast the azimuthally symmetric modes, on which the previous literature has concentrated, with polaritonic guided modes, which propagate in a different regime close to the plasmonic resonance of the waveguide. Forward and backward modes may be envisioned in this latter regime, traveling with subdiffraction cross section along the cylindrical interface between plasmonic and nonplasmonic materials. In general, two oppositely …


On Fractional Paradigm And Intermediate Zones In Electromagnetism: Ii. Cylindrical And Spherical Observations, Nader Engheta Jan 2008

On Fractional Paradigm And Intermediate Zones In Electromagnetism: Ii. Cylindrical And Spherical Observations, Nader Engheta

Nader Engheta

Extending our previous work for the planar case [1], in this Letter we present fractionalization of the kernels of integral transforms that link the field quantities over two coaxial cylindrical surfaces of observation for the two-dimensional (2-D) monochromatic wave propagation, and over two concentric spherical surfaces of observation for the three-dimensional (3-D) wave propagation. With the proper radial normalizations, we show that the fractionalized kernels, with fractionalization parameter ν that here could attain complex values between zero and unity, can effectively be regarded as the kernels of the integral transforms that provide the radially normalized field quantities over the coaxial …


Theory Of Linear Chains Of Metamaterial/Plasmonic Particles As Subdiffraction Optical Nanotransmission Lines, Andrea Alù, Nader Engheta Jan 2008

Theory Of Linear Chains Of Metamaterial/Plasmonic Particles As Subdiffraction Optical Nanotransmission Lines, Andrea Alù, Nader Engheta

Nader Engheta

Here we discuss the theory and analyze in detail the guidance properties of linear arrays of metamaterial/ plasmonic small particles as nanoscale optical nanotransmission lines, including the effect of material loss. Under the assumption of dipolar approximation for each particle, which is shown to be accurate in the geometry of interest here, we develop closed-form analytical expressions for the eigenmodal dispersion in such arrays. With the material loss included, the conditions for minimal absorption and maximum bandwidth are derived analytically by studying the properties of such dispersion relations. Numerical examples with realistic materials, including their ohmic absorption and frequency dispersion, …


Cerenkov Radiation In Chiral Media, Nader Engheta, Sassan Bassiri Jan 2008

Cerenkov Radiation In Chiral Media, Nader Engheta, Sassan Bassiri

Nader Engheta

In this paper, the Cerenkov radiation in an unbounded homogeneous isotropic chiral medium is studied and analyzed classically. Starting from the Maxwell equations and the proposed constitutive relations for isotropic chiral media, we formulate the problem for the electric and magnetic fields emitted from a charged particle moving with a constant speed in a chiral medium, and find a formal solution for the electromagnetic field components and energy spectral density of radiation. Notable features, such as double cone of propagation, and important characteristics of the Cerenkov radiation in such media in terms of the relative velocity of the particle with …


Far-Field Subdiffraction Optical Microscopy Using Metamaterial Crystals: Theory And Simulations, Alessandro Salandrino, Nader Engheta Jan 2008

Far-Field Subdiffraction Optical Microscopy Using Metamaterial Crystals: Theory And Simulations, Alessandro Salandrino, Nader Engheta

Nader Engheta

Here we suggest and explore theoretically an idea for a far-field scanless optical microscopy with a subdiffraction resolution. We exploit the special dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal’s output surface with a compressed angular spectrum, resulting in a "magnified" image. This can provide a far-field imaging system with a resolution beyond the diffraction limits while no scanning is needed.