scholarly journals Isotropic-medium three-dimensional cloaks for acoustic and electromagnetic waves

2012 ◽  
Vol 111 (5) ◽  
pp. 053105 ◽  
Author(s):  
Yaroslav Urzhumov ◽  
Nathan Landy ◽  
David R. Smith
Keyword(s):  
Isotropic Medium ◽  
Electromagnetic Waves ◽  
Three Dimensional

scholarly journals Oblique propagation of electromagnetic waves in a slowly-varying non-isotropic medium

1936 ◽  
Vol 155 (885) ◽  
pp. 235-257 ◽  
Keyword(s):  
Magnetic Field ◽  
Differential Equations ◽  
Electron Density ◽  
Isotropic Medium ◽  
Electromagnetic Waves ◽  
Mathematical Theory ◽  
Stratified Medium ◽  
Oblique Propagation ◽  
Isotropic Media ◽  
Mathematical Justification

The influence of the earth’s magnetic field on the propagation of wireless waves in the ionosphere has stimulated interest in the problem of the propagation of electromagnetic waves through a non-isotropic medium which is stratified in planes. Although the differential equations of such a medium have been elegantly deduced by Hartree,f it appears that no solution of them has yet been published for a medium which is both non-isotropic and non-homogeneous. Thus the work of Gans and Hartree dealt only with a stratified isotropic medium, while in the mathematical theory of crystal-optics the non-isotropic medium is always assumed to be homogeneous. In the same way Appleton’s magneto-ionic theory of propagation in an ionized medium under the influence of a magnetic field is confined to consideration of the “ characteristic ”waves which can be propagated through a homogeneous medium without change of form. In applying to stratified non-isotropic media these investigations concerning homogeneous non-isotropic media difficulty arises from the fact that the polarizations of the characteristic waves in general vary with the constitution of the medium, and it is not at all obvious that there exist waves which are propagated independently through the stratified medium and which are approximately characteristic at each stratum. The existence of such waves has usually been taken for granted, although for the ionosphere doubt has been cast upon this assumption by Appleton and Naismith, who suggest that we might “ expect the components ( i. e ., characteristic waves) to be continually splitting and resplitting”, even if the increase of electron density “ takes place slowly with increase of height”. It is clear that, until the existence of independently propagated approximately characteristic waves has been established, at any rate for a slowly-varying non-isotropic medium, no mathematical justification exists for applying Appleton's magnetoionic theory to the ionosphere. It is with the provision of this justification that we are primarily concerned in the present paper. This problem has been previously considered by Försterling and Lassen,f but we feel that their work does not carry conviction because they did not base their calculations on the differential equations for a non-homo-geneous medium, and were apparently unable to deal with the general case in which the characteristic polarizations vary with the constitution of the medium.

scholarly journals Quantum Structured Light: Non-classical Spin Texture of Twisted Single-photon Pulses

2021 ◽  
Author(s):  
Li-Ping Yang ◽  
Zubin Jacob
Keyword(s):  
Spin Density ◽  
Electromagnetic Waves ◽  
Single Photon ◽  
Structured Light ◽  
Three Dimensional ◽  
Quantum Spin ◽  
Single Photons ◽  
Spin Order ◽  
Spin Noise ◽  
Spin Texture

Abstract Classical structured light with controlled polarization and orbital angular momentum (OAM) of electromagnetic waves has varied applications in optical trapping, bio-sensing, optical communications and quantum simulations. The classical electromagnetic theory of such structured light beams and pulses have advanced significantly over the last two decades. However, a framework for the quantum density of spin and OAM for single-photons remains elusive. Here, we develop a theoretical framework and put forth the concept of quantum structured light for space-time wavepackets at the single-photon level. Our work marks a paradigm shift beyond scalar-field theory as well as the paraxial approximation and can be utilized to study the quantum properties of the spin and OAM of all classes of twisted quantum light pulses. We capture the uncertainty in full three-dimensional (3D) projections of vector spin demonstrating their quantum behavior beyond the conventional concept of classical polarization. Even in laser beams with high OAM along the propagation direction, we predict the existence of large OAM quantum fluctuations in the transverse plane which can be verified experimentally. We show that the spin density generates modulated helical texture beyond the paraxial limit and exhibits distinct statistics for Fock-state vs. coherent-state twisted pulses. We introduce the quantum correlator of photon spin density to characterize the nonlocal spin noise providing a rigorous parallel with fermionic spin noise operators. Our work paves the way for quantum spin-OAM physics in twisted single photon pulses and also opens explorations for new phases of light with long-range spin order.

Compact Dual-Passband Three-Dimensional FSS with Good Angular Stability and Both-Side Fast Roll-Off Characteristics

2021 ◽  
Vol 36 (6) ◽  
pp. 664-669
Author(s):  
Zhengyong Yu ◽  
Baozhu Li ◽  
Shenggao Ding ◽  
Wanchun Tang
Keyword(s):  
Electromagnetic Waves ◽  
Electromagnetic Coupling ◽  
Three Dimensional ◽  
Frequency Selective Surface ◽  
Resonant Mode ◽  
Unit Cell ◽  
Angular Stability ◽  
Propagation Path ◽  
Annular Slot ◽  
Parallel Plate Waveguide

A compact dual-passband three-dimensional (3D) frequency selective surface (FSS) is proposed based on multiple square coaxial waveguides (SCWs), which exhibits good angular stability and both-side fast roll-off characteristics. The unit cell of the proposed 3D FSS is composed of one parallel plate waveguide (PPW) propagation path and two SCW propagation paths. By etching a centered annular slot, each SCW path forms two identical short SCWs. Each short SCW inherently generates one square slot resonance. In each SCW path, on the account of electromagnetic coupling between two square slot resonators provided by two short SCWs, the square slot resonant mode will split into even-/odd-resonant modes. Accordingly, each SCW path can provide a flat second-order passband with two transmission poles. Due to the reflection and out of phase of electromagnetic waves, four transmission zeros located at both sides of the passbands are introduced for high frequency selectivity, realizing both-side fast roll-off performances. In order to explain the operating principle, the electric-field distributions at transmission-zero/pole frequencies are investigated. Finally, an FSS prototype is fabricated and measured, and the results exhibit good angular stability for both TE and TM polarizations under incident angles from 0° to 60°. In addition, the proposed 3D FSS has a compact unit cell.

scholarly journals The Foshan Total Lightning Location System in China and Its Initial Operation Results

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 149 ◽  
Author(s):  
Li Cai ◽  
Xin Zou ◽  
Jianguo Wang ◽  
Quanxin Li ◽  
Mi Zhou ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Radar Data ◽  
Time Of Arrival ◽  
Initial Operation ◽  
Lightning Strikes ◽  
Location System ◽  
Lightning Location System ◽  
Total Lightning ◽  
Operation Results

In the summer of 2013, a three-dimensional (3D)-based Foshan Total Lightning Location System (FTLLS), embedded with differential time of arrival (DTOA) techniques, was installed and started its operation in Foshan, Guangdong Province, China. In this paper, the geographical distribution and set-up information of FTLLS, the estimated locating errors and locating results, as well as its initial operation results are presented. FTLLS consists of nine sub-stations that receive electromagnetic waves associated with lightning discharges and locates VLF/LF (200 Hz–500 kHz) radiation sources in 3D. The remote sub-stations acquired triggered waveforms with a duration of 0.5 ms, a resolution of 12-bits, and a GPS-based sferic time tags of 24 h per day. Cloud-to-ground (CG) lightning events, intra-cloud (IC) lightning events and narrow bipolar events (NBEs) were located by FTLLS. Based on the Monte Carlo simulation, the two-dimensional horizontal location error is basically less than 100 m, and the vertical error (altitude) is less than 200 m when the lightning event occurs within the network. On the other hand, over 14 million lightning strikes were recorded successfully by FTLLS during the period of May to October in 2014, among which IC events, CG events and NBEs accounted for 65%, 34% and 1%, respectively. It is shown that FTLLS is capable of a fine three-dimensional (3D) location, in which the altitude parameters obtained are reasonable and well consistent with observed data in the previous studies. The location results of thunderstorms were additionally verified through simultaneously-observed radar data.

scholarly journals Evaluation of the Laguerre–Gaussian mode purity produced by three-dimensional-printed microwave spiral phase plates

2020 ◽  
Vol 7 (7) ◽  
pp. 200493
Author(s):  
D. Isakov ◽  
Y. Wu ◽  
B. Allen ◽  
P. S. Grant ◽  
C. J. Stevens ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Direct Fabrication ◽  
Dielectric Lens ◽  
Gaussian Mode ◽  
Phase Plates ◽  
Mode Purity ◽  
Aided Design ◽  
Spiral Phase

Computer-aided design software and additive manufacturing provide flexibility for the direct fabrication of multi-material devices. This design and fabrication versatility has been investigated for the manufacture of dielectric spiral phase plates (SPP) that generate electromagnetic waves with helical wavefronts. Three types of SPPs designed to produce an orbital angular momentum (OAM) mode number l = |1| were additively manufactured using material extrusion and polyjet fabrication methods. The OAM mode characteristics of the transformed helical microwaves as a function of the SPP geometrical features were investigated experimentally in the 12–18 GHz frequency range. The SPPs were further combined with an additively manufactured dielectric lens that provided a marked improvement in OAM mode purity. Finally, multiplexing and de-multiplexing of two OAM modes were demonstrated successfully using an optimum SPP geometry and arrangement.

scholarly journals Electromagnetic radiation of oscillating thin films

2019 ◽  
Vol 30 ◽  
pp. 06004
Author(s):  
Alexander V. Kharlanov
Keyword(s):  
Thin Films ◽  
Numerical Simulation ◽  
Electromagnetic Radiation ◽  
Electromagnetic Fields ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Cell Group ◽  
Exchange Of Information ◽  
Dimensional Cell

This paper deals with the electromagnetic fields generated by charges moving with the membrane. The numerical simulation of electromagnetic radiation of oscillating three-dimensional cell it is carried out. The issues of cell group radiation are also considered. Dependences of the field on distance and time are presented. A hypothesis about possible exchange of information between cells by means of electromagnetic waves is made.

scholarly journals Topology optimization for three-dimensional electromagnetic waves using an edge element-based finite-element method

2016 ◽  
Vol 472 (2189) ◽  
pp. 20150835 ◽  
Author(s):  
Yongbo Deng ◽  
Jan G. Korvink
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Topology Optimization ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Free Condition ◽  
Edge Element ◽  
Divergence Free ◽  
The Magnetic Field ◽  
Element Method

This paper develops a topology optimization procedure for three-dimensional electromagnetic waves with an edge element-based finite-element method. In contrast to the two-dimensional case, three-dimensional electromagnetic waves must include an additional divergence-free condition for the field variables. The edge element-based finite-element method is used to both discretize the wave equations and enforce the divergence-free condition. For wave propagation described in terms of the magnetic field in the widely used class of non-magnetic materials, the divergence-free condition is imposed on the magnetic field. This naturally leads to a nodal topology optimization method. When wave propagation is described using the electric field, the divergence-free condition must be imposed on the electric displacement. In this case, the material in the design domain is assumed to be piecewise homogeneous to impose the divergence-free condition on the electric field. This results in an element-wise topology optimization algorithm. The topology optimization problems are regularized using a Helmholtz filter and a threshold projection method and are analysed using a continuous adjoint method. In order to ensure the applicability of the filter in the element-wise topology optimization version, a regularization method is presented to project the nodal into an element-wise physical density variable.

ELECTROMAGNETIC RADIATION INDUCED BY A GRAVITATIONAL WAVE

1995 ◽  
Vol 04 (02) ◽  
pp. 207-213
Author(s):  
N.I. KOLOSNITSYN
Keyword(s):  
Gravitational Wave ◽  
Electromagnetic Waves ◽  
Maxwell Equations ◽  
Three Dimensional ◽  
Geodesic Equation ◽  
Electromagnetic Signal ◽  
The Matrix ◽  
Radiation Induced ◽  
Isotropic Geodesic ◽  
Laser Interferometric

Conversion of a gravitational wave into an electromagnetic one in a laser coherent emission field is studied. As a result two electromagnetic waves are created. For calculation the Maxwell equations in three-dimensional vector form are used. Optimal detection of the gravitational wave is discussed. In a particular case it is the laser interferometric antenna. This approach is identical to those based on integration of the isotropic geodesic equation, the eikonal equation, giving the three-pulsing response of the electromagnetic signal obtained by Estabrook and Wahlquist. It also results in the matrix method developed by Vinet for calculation of laser interferometric antennae.

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