Plane Electromagnetic Wave Research Articles

Electromagnetic Response of a Uniformly Moving Resistive Sheet

ABSTRACTBy using the finite‐difference time‐domain (FDTD) method and a two‐port network model, this letter investigates the response of a uniformly moving resistive sheet to illuminating electromagnetic plane waves, at normal incidence. The numerical Doppler frequency shifts and scattering matrix are matched with curve‐fitting expressions. The effects of motion on the impedance matrix, the chain matrix, and the continuity equations are analyzed. Moreover, the total energy of the transferred and reflected waves are studied for the cases of a resistive sheet moving toward or away from the plane wave source.

Interception force assisted optical pulling of a dipole nanoparticle in a single plane wave

The optical pulling force is generally believed to originate from the recoil force due to the simultaneous excitation of multipoles in the particle, which overcomes the interception force contributing to the optical pushing force. However, we show that the interception force can induce optical pulling force on a small isotropic spherical particle with gain in a uniform electromagnetic plane wave, in which multipole excitation is negligible within the dipole regime. Based on the multipole expansion theory, a rigorous analytical expression is derived for optical force acting on a spherical particle of arbitrary size and composition illuminated by a single plane wave, regardless of its polarization. The analytical results show that the interception force, which is typically positive in a conventional dielectric particle under illumination of a single plane wave, undergoes a crossover from positive to negative by introducing appropriate gain into the dipolar dielectric nanoparticle, thereby giving rise to the optical pulling. It’s deserved to be noted that the optical pulling force assisted by the interception force does not weaken in magnitude, in fact, it exhibits a stronger magnitude compared to the optical pushing force experienced by a corresponding conventional dielectric particle.

Coherent radiation of an electron bunch colliding with an intense laser pulse

We study the conditions for coherent radiation of an electron bunch driven by a counterpropagating strong pulsed electromagnetic plane wave. We derive the spectrum of the coherent radiation and show that it is emitted backward with respect to the laser propagation direction and has a very narrow angular spread. We demonstrate that for a solid density plasma coherent radiation extends to frequencies up to hundreds of keV, thereby enhancing the low-frequency part of the spectrum by many orders of magnitude. Our analytical findings are tested with three-dimensional particle-in-cell simulations of an electron bunch passing through a laser pulse, clearly demonstrating how the coherence can essentially modify the observed radiation spectrum. Published by the American Physical Society 2024

Quadrupole mode plasmon resonance enabled dual-band metamaterial for refractive index sensing application

In this paper, design and fabrication of a dual-band near-zero index metamaterial (MTM) structure using copper on an epoxy resin fiber (FR-4) dielectric substrate is reported for refractive index sensing applications. The primary objective is to achieve dual-band operation spanning a 1–15 GHz frequency range, with a specific focus on achieving a broad bandwidth in the C-band. The resonance of the MTM structure was ascribed to the coupling of plane electromagnetic waves with surface plasmon polaritons on the structure, resulting in a quadrupole plasmon resonance mode. Furthermore, transmission characteristics of the fabricated MTM structure were experimentally measured and found to align closely with the simulated results obtained through the finite element method in COMSOL Multiphysics. The designed MTM structure demonstrates negative and near-zero permittivity at resonance frequencies, enabling left-handed and near-zero index behavior in dual microwave frequency bands. Under room temperature conditions, the MTM sensor exhibited sensitivities of 1 GHz/RIU and 3 GHz/RIU at resonance frequencies of 2.7 and 7.3 GHz, respectively. Consequently, the MTM structure exhibits significant potential for diverse applications, serving as a valuable component in sensors, detectors, and optoelectronic devices operating in the GHz region.

Numerical analysis for temporal and spectral responses of electromagnetic waves in spatially homogeneous time varying medium

This paper presents simple numerical solutions for electromagnetic plane waves in spatially homogenous time varying medium. The solution is based on converting the resulting second order differential equation into two combined ordinary differential equations which are solved numerically by using the built-in ode113 function in Matlab. By using this method, the time domain responses of the electric and magnetic fields at fixed point in space are obtained. The proposed method is applied on two cases: linearly time varying medium and sinusoidally time varying medium. The corresponding frequency domain response is obtained by using inverse Fourier transformation of the obtained time domain response. The proposed method is compared with FDTD solution. It is found that the proposed method has the same accuracy of FDTD with much less computational time.

Evolution of an Overlapped Bandgap and Topological Flat Bands in a Higher‐Order Valley Photonic Insulator Based on Dendritic Structure

AbstractRobust edge states and corner states in photonic topological insulators provide effective ways to manipulate the propagation of electromagnetic waves. Bandgaps of the previously reported photonic topological insulators are independent of each other. In this paper, a higher‐order valley photonic insulator composed of arrays of dendritic structure is designed. The band structure shows an overlapped bandgap is observed, and the overlapped bandgap divides the band structure into three bandgaps. The evolution of the overlapped bandgap is investigated by changing the geometric parameters and increasing the fractal to break the C3v symmetry drastically. Besides, it is notable that the band structure of the proposed valley photonic insulator is flat bands. It is demonstrated that undistorted transmission can be observed as a plane electromagnetic wave transmits through the proposed valley photonic insulator. The interface consisting of two valley photonic structures with distinct topological nontrivial phases is constructed. Edge states and corner states with strong energy localization are obtained in multi‐band frequencies. Remarkably, two triangular structures with different Wannier center configurations both have corner states in the same bandgap, which does not obey the valley selectivity. The phenomenon is caused by the weak valley locking property due to the overlapped bandgap. The proposed valley photonic insulators are expected to benefit applications in optical devices such as topological lasers.

Study of the reflection of a plane electromagnetic wave from a layer of chiral metamaterial located on a conducting plane, taking into account the inhomogeneity and dispersion of material parameters

To reduce the radar signature of moving objects, such as cars, boats, manned and unmanned aircraft systems, technologies for creating broadband radio-absorbing materials are being actively developed and improved. Among such materials are composites and chiral metamaterials, which have unique characteristics that make it possible to effectively control the reflection and rotation of the plane of polarization of electromagnetic waves. In addition, devices included in the structure of infocommunication systems are subject to electromagnetic radiation, which can cause undesirable effects and interference. Radio-absorbing coatings based on metamaterials can significantly reduce the reflection of electromagnetic waves and effectively counteract the effects of electromagnetic radiation. The purpose of this study is to solve the scientific and technical problem of determining the reflection coefficients of electromagnetic waves from a radio-absorbing material consisting of a chiral metamaterial located on a conducting surface. The main objective of the work is to study the interaction of a plane electromagnetic wave with the specified layer of metamaterial located on a conducting plane, taking into account the inhomogeneity and dispersion of material parameters.

Dynamics, quantum states and Compton scattering in nonlinear gravitational waves

The classical dynamics and the construction of quantum states in a plane wave curved spacetime are examined, paying particular attention to the similarities with the case of an electromagnetic plane wave in flat spacetime. A natural map connecting the dynamics of a particle in the Rosen metric and the motion of a charged particle in an electromagnetic plane wave is unveiled. We then discuss how this map can be translated into the quantum description by exploiting the large number of underlying symmetries. We examine the complete analogy between Volkov solutions and fermion states in the Rosen chart and properly extend this to massive vector bosons. We finally report the squared S-matrix element of Compton scattering in a sandwich plane wave spacetime in the form of a two-dimensional integral.

Parameter Extraction of Accelerated Moving Targets under Non-Quasi-Axial Incidence Conditions Based on Vortex Electromagnetic Wave Radar

Vortex electromagnetic wave radar carrying orbital angular momentum can compensate for the deficiency of planar electromagnetic wave radar in detecting motion parameters perpendicular to the direction of electromagnetic wave propagation, thus providing more information for target recognition, which has become a hot research field in recent years. However, existing research makes it difficult to obtain the acceleration and rotation centers of targets under non-quasi-axial incidence conditions of vortex electromagnetic waves. Based on this, this article proposes a variable speed motion target parameter extraction method that combines single element and total element echoes. This method can achieve three-dimensional information extraction of radar targets based on a uniform circular array (UCA). Firstly, we establish a non-quasi-axis detection echo model for variable-speed moving targets and extract echoes from different array elements. Then, a single element echo is used to extract the target’s range slow time profile and obtain the target’s rotation center z coordinate. We further utilize the target linear, angular Doppler frequency shift extremum, and median information to extract parameters such as target acceleration, tilt angle, rotation radius, and rotation center x and y coordinates. We analyzed the impact of different signal-to-noise ratios and motion states on parameter extraction. The simulation results have verified the effectiveness of the proposed algorithm.

Nonlinear helicity anomalies in the cyclotron resonance photoresistance of two-dimensional electron systems

Our studies of the cyclotron resonance (CR) photoresistance in GaAs-based two-dimensional electron systems (2DES) reveal an anomalously low sensitivity to the helicity of the incoming circularly polarized terahertz radiation. We find that this anomaly is strongly intensity dependent, and the ratio of the low-temperature photoresistance signals for the CR-active (CRA) and CR-inactive (CRI) polarities of magnetic field increases with lowering power, but, nevertheless, remains substantially lower than expected from conventional theory assuming interaction of the plane electromagnetic wave with the uniform 2DES. Our analysis shows that all data can be well described by the nonlinear CR-enhanced electron gas heating in both CRA and CRI regimes. This description, however, does not specify the source of anomalous CRI absorption that remains unclear. Published by the American Physical Society 2024

Rapid Prototyping of Anomalous Reflective Metasurfaces Using Spray-Coated Liquid Metal.

Reconfigurable intelligent surfaces (RISs) have the potential to improve wireless communication links by dynamically redirecting signals to dead spots. Although a reconfigurable surface is best suited for environments in which the reflected signal must be dynamically steered, there are cases where a static, non-reconfigurable anomalous reflective metasurface can suffice. In this work, spray-coated liquid metal is used to rapidly prototype an anomalous reflective metasurface. Using a pressurized air gun and a plastic thin-film mask, a metasurface consisting of a 6 × 4 array of Galinstan liquid-metal elements is sprayed within minutes. The metasurface produces a reflected wave at an angle of 28° from normal in response to a normal incident 3.5-GHz electromagnetic plane wave. The spray-coated liquid-metal metasurface shows comparable results to an anomalous reflective metasurface with copper elements of the same dimensions, demonstrating that this liquid-metal fabrication process is a viable solution for the rapid prototyping of anomalous reflective metasurfaces.

Expansion of a plane electromagnetic wave over spherical waves in case of arbitrary direction of propagation

Expansion of a plane electromagnetic wave over spherical waves in case of arbitrary direction of propagation

A numerical investigation of effective optical characteristics of dielectric mixture layer on Si sphere by FDTD method

This paper reports on a numerical simulation of the optical characteristics of a dielectric mixture layer formed on a Si substrate using the finite-difference time-domain (FDTD) method. This study investigated the validity of using effective medium approximation (EMA) layers in thin mixture film problems with the optical constants of bulk materials. The complex reflection coefficients of Si substrates with randomly distributed thin mixture films fabricated from water/SiO2 and water/carbonaceous materials were numerically evaluated at normal and oblique incidences of plane electromagnetic waves via the FDTD principle, and the possible effects of the mixture layers on the effective optical characteristics were investigated. We observed that Bruggeman’s model based on EMA provides a good prediction of the behaviour of the plane wave reflected by the Si surface with randomly distributed mixture layers. The results also suggested that mixture layers have effects under oblique incidence, but they have no significant impact under normal incidence.

Analytical solutions for quantum radiation reaction in high-intensity lasers

While the Landau-Lifshitz equation, which describes classical radiation reaction, can be solved exactly and analytically for a charged particle accelerated by a plane electromagnetic wave, no such solutions are available for quantum radiation reaction (the recoil arising from the successive, incoherent emission of hard photons). Yet upcoming experiments with ultrarelativistic electron beams and high-intensity lasers will explore the regime where both radiation-reaction and quantum effects are important. Here we present analytical solutions for the mean and variance of the energy distribution of an electron beam that collides with a pulsed plane electromagnetic wave, which are obtained by means of a perturbative expansion in the quantum parameter χ0. These solutions capture both the quantum reduction in the radiated power and the stochastic broadening, and are shown to be accurate across the range of experimentally relevant collision parameters, i.e., GeV-class electron beams and laser amplitudes a0≲200. Published by the American Physical Society 2024

Exactness of the First Born Approximation in Electromagnetic Scattering

Abstract For the scattering of plane electromagnetic waves by a general possibly anisotropic stationary linear medium in three dimensions, we give a condition on the permittivity and permeability tensors of the medium under which the first Born approximation yields the exact expression for the scattered wave whenever the incident wavenumber k does not exceed a preassigned value α. We also show that under this condition the medium is omnidirectionally invisible for k ≤ α/2, i.e. it displays broadband invisibility regardless of the polarization of the incident wave.

Can a spatially anisotropic random scatterer produce a rotationally symmetric scattered momentum flow in the far zone?

The question is examined as to whether the far-zone distribution of the electromagnetic momentum of the light generated by scattering on a spatially anisotropic random medium can be the same in every azimuthal angle of scattering. We show that the rotationally symmetric distribution of the scattered momentum flow in the far zone may be realized, provided that the structural parameters of both the scattering medium and the incident light source are chosen appropriately, when a polychromatic electromagnetic plane wave is scattered by an anisotropic, Gaussian, Schell-model medium. We derive the necessary and sufficient conditions for producing such a distribution. It is found that the scatterers have the same effective widths (σx, σy) but different effective correlation widths (μx, μy), yet all of them have the ability to produce rotationally symmetric distributions of the scattered momentum flow in the far zone. The same is true of the media having the same (μx, μy) but different (σx, σy). It is also found that the realization of the rotationally symmetric scattered momentum flow is independent of the spectral degree of polarization of the incident light source-the rotationally symmetric distribution of the scattered momentum flow is always realizable regardless of whether the incident light field is fully polarized, partially polarized or completely unpolarized. Our results have potential practical applications in optical mircromanipulation such as optical trapping of particles, especially when the optical forces used to manipulate the particles are required to be rotationally symmetric.

The Poynting Vector Field Singularities: Effects of Symmetry and Its Violation

AbstractThe phenomenological theory revealing the generic effects of the problem symmetry, its violation, and energy conservation law on the singularities of the Poynting vector field is presented. The bifurcation scenario of formation (annihilation) of the singularities under variations of the problem parameters is elucidated. The results describe the singularities in scattering a linearly polarized plane electromagnetic wave. However, they are valid for any configuration of the incident beam at its scattering by a subwavelength particle. The author shows that topological changes in the pattern of the Poynting vector field occur through a finite number of pitchfork bifurcations. It means that the patterns are topologically stable under variations of the problem parameter(s) that lie between the bifurcation values. The latter ensures that the discussed topological properties of the problem are robust to weak symmetry violation, which is inevitable in any actual experiment. The general consideration is illustrated by a detailed study of singularities in scattering by an infinite right circular germanium cylinder. The results open the possibility of fitting and controlling radiation patterns on subwavelength scales important for various nanotechnologies.

Stationary Bragg reflection of laser light in inhomogeneous absorbing plasmas inside inertial confinement fusion Hohlraums

Laser-produced plasma in inertial confinement fusion (ICF) Hohlraums are marked with density non-uniformity whose length scale can go down to micrometers. This scale is of the order of the laser wavelength. The WKB approximation, which is classically used in radiation-hydrodynamic codes to compute the laser trajectory, cannot correctly take into account such small-scale inhomogeneity of the plasma. Going beyond this approximation, we predict a novel mechanism for the laser reflection. We show that an electromagnetic plane wave with wave number k resonates with the kB=2 k Fourier component of a multimode perturbation of the background density and generates a reflected wave. It is the first time that this reflection is considered for stationary inhomogeneous ICF plasmas, and the energy absorption is taken into account. This mechanism, which is a form of Bragg reflection, can occur away from the critical surface and generate a drift of the location of the laser absorption. Furthermore, this absorption will be periodically modulated with a kB wave number. The stationary Bragg reflection can explain ongoing discrepancies between experimental and numerical data about laser trajectory and absorption in ICF Hohlraums.

A Novel Forward-Looking Target Reconstruction Method With Electromagnetic Vortex Interferometry

For the target in the radar forward-looking sight, only the range-history phase information can be exhibited when the plane electromagnetic (EM) wave illuminating. For traditional approaches, the reconstruction of target azimuthal information requires antennas configured at both ends of the long baseline to implement multi-angle observation, usually leading to a baseline length burden. In contrast, the target’s azimuth information, related to the orbital angular momentum (OAM), is directly modulated in the new-dimensional echo phase by the antenna radiating the vortex EM wave, which provides a new foundation for target azimuth reconstruction. In this article, a novel forward-looking target reconstruction methodology with EM vortex interferometry is proposed, and the target 3-D imaging with different OAM modes interferometry strategies is achieved as well. The developed approach can improve the target azimuthal reconstruction error performance without increasing the length of short baseline and image registration. Comprehensive results of simulated data and real-world measured data are performed to validate the effectiveness and anti-noise robustness of the proposals.

Influence of spatial dispersion in metal on optical characteristics of a magnetoplasmonic layered nanoparticle cluster

In the current work, the diffraction problem of a plane electromagnetic wave on a cluster of two layered nanocylinders consisting of a magnetoplasmonic core and a gold shell is considered. The arising effects of spatial dispersion in the gold shell are taken into account within the framework of the generalized nonlocal optical response theory. Based on the discrete source method scheme, an analysis of the influence of the mutual arrangement of particles, their deformation, and the effect of spatial dispersion on the behaviour of the absorption cross-section and the near-field enhancement factor is conducted. It is shown that the position of the plasmon resonance can be shifted to the transparency region of biological tissues by varying the distance between particles and the core material. It has been established that taking into account spatial dispersion in the gold shell leads to a decrease in intensity and a slight shift of the plasmon resonance position to the shortwave region, without going beyond the tissue transparency region.