scholarly journals Near-zero-index media as electromagnetic ideal fluids

2020 ◽  
Vol 117 (39) ◽  
pp. 24050-24054
Author(s):  
Iñigo Liberal ◽  
Michaël Lobet ◽  
Yue Li ◽  
Nader Engheta
Keyword(s):  
Optical Interconnects ◽  
Electromagnetic Waves ◽  
Power Flow ◽  
Optical Systems ◽  
Dielectric Particles ◽  
Electromagnetic Power ◽  
Interesting Connection ◽  
Ideal Fluids ◽  
Local Properties ◽  
Zero Index

Near-zero-index (NZI) supercoupling, the transmission of electromagnetic waves inside a waveguide irrespective of its shape, is a counterintuitive wave effect that finds applications in optical interconnects and engineering light–matter interactions. However, there is a limited knowledge on the local properties of the electromagnetic power flow associated with supercoupling phenomena. Here, we theoretically demonstrate that the power flow in two-dimensional (2D) NZI media is fully analogous to that of an ideal fluid. This result opens an interesting connection between NZI electrodynamics and fluid dynamics. This connection is used to explain the robustness of supercoupling against any geometrical deformation, to enable the analysis of the electromagnetic power flow around complex geometries, and to examine the power flow when the medium is doped with dielectric particles. Finally, electromagnetic ideal fluids where the turbulence is intrinsically inhibited might offer interesting technological possibilities, e.g., in the design of optical forces and for optical systems operating under extreme mechanical conditions.

Diffraction of Electromagnetic Waves by a Semi-Infinite Screen in a Layered Medium

1975 ◽  
Vol 53 (14) ◽  
pp. 1305-1317 ◽  
Author(s):  
Wiebe G. Heitman ◽  
P. M. van den Berg
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Power Flow ◽  
Layered Medium ◽  
Plane Electromagnetic Wave ◽  
Flow Density ◽  
Two Dimensional ◽  
Electromagnetic Power

The diffraction of a plane electromagnetic wave by a semi-infinite screen in one of the plane interfaces of a layered medium is investigated theoretically. The screen of vanishing thickness is assumed to be electrically perfectly conducting. Two separate two dimensional scalar problems are dealt with, viz. the case of E polarization and H polarization. The resulting unknown field functions are determined with the aid of the Wiener–Hopf technique. Subsequently, the electromagnetic power flow density is calculated at different locations and as a function of the electromagnetic contrast of the different media.

scholarly journals Magnetite Particle Presence in the Human Brain: A Computational Dosimetric Study to Emphasize the Need of a Complete Assessment of the Electromagnetic Power Deposition at 3.5 GHz

2021 ◽  
Vol 11 (5) ◽  
pp. 7720-7729
Author(s):  
D. Vatamanu ◽  
S. Miclaus
Keyword(s):  
Human Brain ◽  
Electromagnetic Waves ◽  
Eddy Currents ◽  
Magnetic Losses ◽  
Power Deposition ◽  
Emit Radiation ◽  
Electromagnetic Power ◽  
Communication Devices ◽  
Dosimetric Study ◽  
Portable Communication

The growing evidence of increased magnetite nanoparticles (both endo- and exo-genic) in the human brain raises the importance of assessing the entire power deposition when electromagnetic waves at GHz frequencies propagate in such tissues. This frequency range corresponds to many popular portable communication devices that emit radiation close to a human's head. At these frequencies, the current dosimetric numerical codes can not accurately compute the magnetic losses part. This is due to the lack of an implemented computational algorithm based on solving the coupled Maxwell and Landau-Lifshitz-Gilbert equations, in the case of magneto-dielectrics, considering eddy currents losses and specific properties of magnetic sub-millimetric particles. This paper focuses on analyzing the limits and the inconsistencies when using commercial dosimetric numerical software to analyze the total absorbed power in brain models having ferrimagnetic content and being exposed to 3.5GHz electromagnetic waves. Magnetic losses computed using Polder’s permeability tensor as constitutive relation lead to unreliable results. However, using such software can provide a preliminary view of the electromagnetic impact of ultra- and super-high frequencies on magnetic-dielectric tissues.

scholarly journals Power flow–conformal metamirrors for engineering wave reflections

2019 ◽  
Vol 5 (2) ◽  
pp. eaau7288 ◽  
Author(s):  
Ana Díaz-Rubio ◽  
Junfei Li ◽  
Chen Shen ◽  
Steven A. Cummer ◽  
Sergei A. Tretyakov
Keyword(s):  
Power Distribution ◽  
Electromagnetic Waves ◽  
Power Flow ◽  
Flow Distribution ◽  
Physical Nature ◽  
Wave Reflections ◽  
Reflected Waves ◽  
Anomalous Reflection ◽  
Unit Cells ◽  
Reflecting Surfaces

Recently, the complexity behind manipulations of reflected fields by metasurfaces has been addressed, showing that, even in the simplest scenarios, nonlocal response and excitation of auxiliary evanescent fields are required for perfect field control. In this work, we introduce purely local reflective metasurfaces for arbitrary manipulations of the power distribution of reflected waves without excitation of any auxiliary evanescent field. The method is based on the analysis of the power flow distribution and the adaptation of the reflector shape to the desired distribution of incident and reflected fields. As a result, we find that these power-conformal metamirrors can be easily implemented with conventional passive unit cells. The results can be used for the design of reflecting surfaces with multiple functionalities and for waves of different physical nature. In this work, we present the cases of anomalous reflection and beam splitting for both acoustic and electromagnetic waves.

Optimization and Inverse-design Techniques for Metalens Synthesis

2021 ◽  
Vol 35 (11) ◽  
pp. 1334-1335
Author(s):  
Sawyer Campbell ◽  
Eric Whiting ◽  
Ronald Jenkins ◽  
Pingjuan Werner ◽  
Douglas Werner
Keyword(s):  
Electromagnetic Waves ◽  
High Performance ◽  
Inverse Design ◽  
Optical Systems ◽  
Challenging Problem ◽  
Phase Gradient ◽  
Unit Cells ◽  
Cell Components ◽  
Meta Atom ◽  
Design Techniques

Phase-gradient metasurfaces enable designers to tailor the behavior of electromagnetic waves at surfaces by exploiting the generalized form of Snell’s law. This ability has led to the investigation of metalenses which have the potential to significantly reduce the size, weight, and power (SWaP) of conventional optical systems. While traditional lenses are made from individual glasses, metalenses are comprised of patterned meta-atom unit Cells which are arranged in such a way so as to give the metalens its desired behavior. Therefore, any metalens’s performance is ultimately determined by that of its underlying unit cell components. However, designing meta-atoms that simultaneously achieve high performance over wide frequency bandwidths and fields-of-view is an extremely challenging problem that is best addressed with powerful optimization and inverse-design techniques.

SCATTERING OF ELECTROMAGNETIC WAVES BY A SINUSOIDALLY STRATIFIED HALF-SPACE: II. DIFFRACTION ASPECTS AT THE RAYLEIGH AND BRAGG WAVELENGTHS

1966 ◽  
Vol 44 (10) ◽  
pp. 2461-2494 ◽  
Author(s):  
T. Tamir
Keyword(s):  
Half Space ◽  
Electromagnetic Waves ◽  
Power Flow ◽  
Formal Solution ◽  
Numerical Data ◽  
Field Pattern ◽  
Flow Properties ◽  
Standing Wave Field ◽  
Plane Wave Incident ◽  
Resonant Behavior

The diffracted field of a plane wave incident obliquely from air onto a sinusoidally modulated half-space is investigated by employing a rigorous formal solution, together with graphical constructions and equivalent circuits, which have already been derived by Tamir and Wang (1966, Part I). The field in the air region is shown to be influenced considerably by Wood's anomalies of the Rayleigh type. The location of these anomalies is determined by the onset of propagation or evanescence for modes in either the air or the dielectric regions; their orders of magnitude are estimated by means of a network which describes the air–dielectric interface. In the stratified dielectric, the field is strongly affected by an interference process that peaks at the Bragg wavelengths and produces a resonant behavior of the modal amplitudes. This results in a strong standing-wave field pattern in the form of repetitive oblong rectangular cells with interesting power-flow properties. Additional details of the fine field structure are treated extensively and numerical data, which are in excellent agreement with the considerations and results obtained by analytical and graphical means, are given.

scholarly journals Determination of adjusted range corrections measured by electro-optical systems

2021 ◽  
Vol 2131 (2) ◽  
pp. 022048
Author(s):  
V I Kushtin ◽  
A N Ivanov
Keyword(s):  
Electromagnetic Waves ◽  
Propagation Speed ◽  
Optical Systems ◽  
Signal Delay ◽  
Atmospheric Models ◽  
Ellipsoidal Model ◽  
Wave Path ◽  
Measured Line ◽  
Different Characteristics

Abstract Electromagnetic radiation used to determine ranges passes through media with different characteristics that affect the electromagnetic waves propagation speed and, accordingly, the accuracy of distance determination. The problem of the radio signal delay due to the influence of the atmosphere is an urgent problem, the solution of which is currently limited mainly to the calculation of range corrections using various atmospheric models. Depending on the required accuracy, the length of the measured line, the range of zenith distances, the availability of information about the state of the atmosphere, a flat, spherical, ellipsoidal model of atmospheres is used to determine the range corrections. In view of the fact that the parameters of the atmosphere characterizing its state along the electromagnetic wave path at the time of measurement, as a rule, are unknown, it becomes necessary to apply one or another hypothesis about the distribution of atmospheric parameters with height. In this paper, we propose a solution to the problem of determining corrections to the measured ranges from the known parameters of the atmosphere only at the initial and final points of the electromagnetic waves’ trajectory.

scholarly journals Manipulating Electromagnetic Waves with Zero Index Materials

10.5772/66663 ◽  
2017 ◽  
Author(s):  
Shiyang Liu ◽  
Jialin Zhou ◽  
Ying Han ◽  
Xinning Yu ◽  
Huajin Chen ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Zero Index

Spectral theory of diffraction of electromagnetic waves by a strip in the plane interface of two semi-infinite media

1979 ◽  
Vol 57 (8) ◽  
pp. 1148-1156 ◽  
Author(s):  
J. M. van Splunter ◽  
P. M. van den Berg
Keyword(s):  
Fourier Transform ◽  
Electromagnetic Waves ◽  
Power Flow ◽  
Plane Electromagnetic Wave ◽  
Plane Waves ◽  
Surface Current ◽  
Iteration Scheme ◽  
Plane Interface ◽  
Flow Density ◽  
Infinite Media

The diffraction of a plane electromagnetic wave by a cylindrical strip in the plane interface of two semi-infinite media has been investigated. For both the case of E polarization and the case of H polarization, the scattered field is written as a continuous superposition of plane waves (spatial Fourier type of integral). The complex amplitudes of these waves are directly related to the spatial Fourier transform of the surface current on the strip. In order to determine the surface current, a relatively simple iteration scheme has been developed. At the numerical calculations we successfully take advantage of the presence of a Fast Fourier Transform procedure. Numerical results pertaining to the power flow density are presented at different locations and as a function of the width of the strip. Furthermore, the scattering cross section of the strip, as a function of the electromagnetic contrast of the different media, is calculated.

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