Resonant Electromagnetic Wave Research Articles

Electromagnetic waves propagating in the string axiverse

Abstract It is widely believed that axions are ubiquitous in string theory and could be dark matter. The peculiar features of axion dark matter are coherent oscillations and a coupling to the electromagnetic field through the Chern–Simons term. In this letter, we study the consequences of these two features of axions with mass in the range $10^{-13}\,{\rm eV}$ to $10^{3}\,{\rm eV}$. First, we study the parametric resonance of electromagnetic waves induced by the coherent oscillation of the axion. Since the resonance frequency is determined by the mass of the axion dark matter, if we detect this signal, we can get information on the mass of the axion dark matter. Second, we study the velocity of light in the background of the axion dark matter. In the presence of the Chern–Simons term, the dispersion relation is modified and the speed of light will oscillate in time. It turns out that the change in the speed of light would be difficult to observe. We argue that future radio wave observations of the resonance can give rise to a stronger constraint on the coupling constant and/or the density of the axion dark matter.

Acoustically actuated ultra-compact NEMS magnetoelectric antennas

State-of-the-art compact antennas rely on electromagnetic wave resonance, which leads to antenna sizes that are comparable to the electromagnetic wavelength. As a result, antennas typically have a size greater than one-tenth of the wavelength, and further miniaturization of antennas has been an open challenge for decades. Here we report on acoustically actuated nanomechanical magnetoelectric (ME) antennas with a suspended ferromagnetic/piezoelectric thin-film heterostructure. These ME antennas receive and transmit electromagnetic waves through the ME effect at their acoustic resonance frequencies. The bulk acoustic waves in ME antennas stimulate magnetization oscillations of the ferromagnetic thin film, which results in the radiation of electromagnetic waves. Vice versa, these antennas sense the magnetic fields of electromagnetic waves, giving a piezoelectric voltage output. The ME antennas (with sizes as small as one-thousandth of a wavelength) demonstrates 1–2 orders of magnitude miniaturization over state-of-the-art compact antennas without performance degradation. These ME antennas have potential implications for portable wireless communication systems.

Analysis on Double Loop Wireless Power Transfer

This paper examines the properties of the double loop wireless power transmitter using numerical simulations. The double loop wireless power transmitter consists of two coupling and parallel loop antennas which transmit field energy through resonant electromagnetic waves. This tech-nology can be applied in RFIDs (Radio Frequency Identification) and re-mote charging scenarios where wires cannot be applied to, including the wireless charging of drones and satellites.

Visible Plasma Clouds With an Externally Excited Spherical Porous Cavity Resonator

A microwave driven resonator is as an electron/ion cloud generator for illumination and plasma source applications. A sustained porous cavity resonator (PCR) glow discharge is externally excited using a resonant frequency electromagnetic (EM) wave that excites large internal electric fields. The resonator with a Q of 300 amplifies the incident electric field by factors of about 100 causing a breakdown of the neutral gas inside the sphere. The rise time of the fields inside the sphere is Q times the wave period. A glowing plasma ball is sustained around the point where the maximum electric fields exceed the plasma-discharge threshold for the low-pressure gas inside the resonator. After the EM pump field is removed, the plasma light source is rapidly quenched. The externally driven spherical PCR was fabricated from a theoretical design of the PCR for a laboratory demonstration of the plasma ball generation system. Using both theory and experiment, basic research has been applied to understand: 1) the EMs of resonator excitation and amplification; 2) the generation of light by glow radio frequency discharge; and 3) the effect of background neutral density of the size and intensity of the glowing plasma clouds. For this study, plasma resonators were constructed for the spherical TM101 and TE101 modes and a TE011 circular-cylindrical cavity. All PCR structures provide the ability to confine a plasma into a desired spatial shape without magnetic fields.

Energy conversion within infrared plasmonic absorption metamaterials for multi-band resonance

The energy conversion within the cross-shaped plasmonic absorber metamaterials (PAM) was investigated theoretically and numerically in the infrared range based on the Poynting's theorem of electromagnetic energy. From the microscopic details, the heat generation owing to the electric current accounts for the majority of the energy conversion, while the magnetic resonance plays a negligible role. The PAMs possess three distinct resonant peaks standing independently, which are attributed to the polarization sensitive excitation of plasmonic resonance. Field redistribution and enhancement associated with multiplex resonant electromagnetic wave passing through the PAM medium provided insight into the energy conversion processes inside the nanostructure. The research results will assist the design of novel plasmon enhanced infrared detectors with multiple-band detection.

A Composite Heterostructure Mesh-shaped Patch Antenna Based on Left Handed Material

In this paper, a composite heterostructure mesh-shaped patch antenna based on left handed material (LHM) is presented. The method of finite difference time domain (FDTD) is used. The results show that electromagnetic wave resonance occurs near 4.52 GHz, where the equivalent permittivity and permeability of composite material are both negative. The composite antenna’s gain improves 9.047 dB, its return loss reduces 20.26 dB compared to the conventional antenna’s ones. The results indicate that this composite patch antenna system can reduce return loss of the antenna and increase the gain obviously.

Polarization sensitivity contributes to multiple band spectra of one mid-infrared absorber

The emerging perfect-absorber metamaterials (PAMs) provide an alternative material approach for the next generation of electromagnetic detection at any frequency band of interest. One type of dual cross-shaped PAMs is developed to obtain multiplex-band spectrum absorption at mid-infrared region. Three distinct absorption peaks are attributed to the polarization sensitivity excitation of the plasmonic resonance. The charge density distributions, which are excited by resonant electromagnetic waves passing through the PAMs medium, provide insights into the observed absorption behavior. We find that the retrieved optical properties of the PAMs including permittivity and permeability are still consistent with the sum of the Drude and Lorentz type models at wavelengths ranging from 2.0 to 10.0 mm. Such multiplex-band absorption properties enable the proposed PAMs a powerful tool for the direct detection of multiple molecular vibrational structures, and for multiple spectra infrared detection.

Investigation of gain effect of multi-band patch antenna based on composite rectangular SRRs

The paper focus on describing the important influence and physical law of the Split_Resonant_Rings (SRRs) based on Left Handed Material (LHM) on patch antennas. The FDTD method, together with FEM method is used to study the characteristics of patch antenna based on composite rectangular SRRs. A novel composite rectangular SRR system is formed by assembling the conventional patch antenna and SRRs, it is found that electromagnetic wave resonance occurs at several bands: GSM (880–960MHz), DCS (1710–1881MHz), and PCS (1850–1990MHz). The electromagnetic wave's “tunnel effect” and evanescent waves’ enhancing effect are formed, which can improve the localization extent of electromagnetic wave's energy apparently, such effects can improve the antenna's radiation gain and its matching condition. The phenomenon indicates that such composite rectangular patch antennas are promising in wireless communications such as mobile phone, satellite communication and aviation.

Study on left-handed effect of composite helices and its application in square frame patch antennas

The finite difference time domain (FDTD) method is used to study the characteristics of composite helices patch antenna based on left-handed effect. The numerical results indicate that electromagnetic wave resonance occurs near f=4.18GHz where the equivalent permittivity and permeability are both negative. In this case, the electromagnetic wave's tunneling effect and evanescent waves’ enhancing effect are formed. Such effects can improve the antenna's radiation gain and its matching condition, and this composite patch antennas’ return loss is much lower compared to conventional antenna. Due to these advantages, the use of composite square frame patch antennas will be extended to mobile communication, satellite communication, aviation, etc.

Surface-plasmon-polariton assisted modification of spontaneous emission of colloidal quantum dots in metal nanostructures

We experimentally demonstrate extraordinary optical transmission (EOT) assisted photoluminescence (PL) of CdSe/CdS colloidal quantum dots (QDs). The quantum dots were encapsulated between a metallic nanostructure and a Bragg reflector to enhance the interaction of spontaneously emitted photons with a resonant electromagnetic surface wave. The measured PL spectrum of the fabricated sample exhibits spectral narrowing and a shift in peak wavelength of 22 nm and 7 nm, respectively. Furthermore, we tested the angular dependence of the signal to confirm the existence of EOT. This demonstration is a critical step towards realizing plasmonic colloidal QD based coherent emitters.

Unguided plasmon-mode resonance in optically excited thin film: exact modal description of Kretschmann–Raether experiment

With the aim of studying electromagnetic surface wave resonance, we rigorously solve the homogeneous and inhomogeneous problem associated with an optically excited thin metallic film. We then demonstrate unambiguously that the excited eigenmode engendering plasmonic resonance in the so-called Kretschmann–Raether configuration is an unguided mode (i.e., with an anti-evanescent structure). This result, challenging the classical interpretation of the outgoing wave condition applied to surface waves, permits a quantitative interpretation of the attenuated total reflection curves.

Highly Ordered Fe–Au Heterostructured Nanorod Arrays and Their Exceptional Near-Infrared Plasmonic Signature

The potential of highly ordered array nanostructures in sensing applications is well recognized, particularly with the ability to define the structural composition and arrangement of the individual nanorods accurately. The use of heterogeneous nanostructures generates an additional degree of freedom, which can be used to tailor the optical response of such arrays. In this article, we report on the fabrication and characterization of well-defined Fe-Au bisegmented nanorod arrays in a repeating hexagonal arrangement. Through an asymmetric etching method, free-standing Fe-Au nanorod arrays on a gold-coated substrate were produced with an inter-rod spacing of 26 nm. This separation distance renders the array capable of sustaining resonant electromagnetic wave coupling between individual rods. Owing to this coupling, the subwavelength arrangement, and the structural heterogeneity, the nanorod arrays exhibit unique plasmonic responses in the near-infrared (NIR) range. Enhanced sensitivity in this spectral region has not been identified for gold-only nanorods of equivalent dimensions. The NIR response offers confirmation of the potential of these highly ordered, high-density arrays for biomedical relevant applications, such as subcutaneous spectroscopy and biosensing.

Room temperature superradiance due to coherent coupling between light and extended single quantum state

We have established the newly-developed growth method of high-quality CuCl thin film based on molecular-beam epitaxy. In qualified films, where harmonized coupling between an excitonic polarization wave and a resonant electromagnetic wave over a range of multiple wavelengths is achieved, we have observed an exceptionally high speed nonlinear response of excitons at room temperature, wherein the excitons decay radiatively before its coherence is destroyed by dephasing. A component with extremely large radiative width can be observed in the nonlinear optical spectrum only when the other components with smaller radiative widths disappear by the room-temperature dephasing. The radiative decay time of the excitonic state with the largest radiative width reaches the order of 100fs, which is much faster than the dephasing process. The mechanism demonstrated by our results contradicts the conventional physical description of light–matter interaction based on the long-wavelength approximation. The shapes of the measured degenerate four-wave mixing spectrum and the radiative decay profile closely reflect those of the calculated induced-polarization spectrum and the radiative decay profile obtained by real-time analysis, respectively.

A 3D Monte Carlo code for the modeling of plasma dynamics and beam formation mechanism in electron cyclotron resonance ion sources

The code here presented is the first part of a Monte Carlo (MC) self-consistent 3D plasma simulator. It is yet able to solve the equation of motion for thousands of independent charged particles. The procedure allows to understand the consequences of each phenomenon introduced in the evolution steps of the code. MC random selection of starting parameters is used for each particles; the environmental conditions enclosed in the simulation are ECRIS magnetic field, resonant electromagnetic wave, initial plasma density distribution and MC calculation of Spitzer collision. The results of the first simulations explain some typical effects as the hollow beam formation and the main plasma deconfinement mechanism.

Electric Field Amplification inside a Porous Spherical Cavity Resonator Excited by an External Plane Wave

A spherical polyhedron constructed from open surface polygons is an electromagnetic wave resonator that can be excited by an external plane wave. The resonant frequencies of the porous sphere depend on the radius of the sphere and the area of the openings in the surface of the sphere. The strength of the internal electric fields varies with the width of the conducting edges that comprise the polyhedron frame. At the optimum edge width, the external EM wave field excites the strongest internal field amplitudes. The WIPL-D EM simulation model is used to determine the optimum porous resonator for polyhedrons with 180 and 960 vertices. All of the cavity modes for a solid spherical cavity resonator can be excited in the porous spherical cavity resonator (PSCR). With a high resonator Q, an EM plane-wave of 1 V/m can excite an internal electric field of over 1000 V/m that takes finite time for fields to build up. The spherical cavity modes provide a variety of electric field distributions at the interior of the PSCR. The PSCR may be used to greatly increase the electric fields of a high power radio beam in order to produce isolated plasma clouds by neutral gas breakdown.

A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave observations in the Earth-ionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfvén waves and particle precipitation related to solar and magnetospheric processes. We review ionospheric processes as well as surface and space weather phenomena that drive the coupling between the troposphere and the ionosphere. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface perturbations and atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and to solve inverse problems and outline in a final section a few challenging subjects that are important to advance our understanding of tropospheric-ionospheric coupling.

Investigation of a patch antenna based on I-shaped left-handed material

The paper investigated a patch antenna based on I-shaped left-handed materials by using the method of finite difference time domain (FDTD). The results show that there exists a wave resonance state at 6.7 GHz, where the real part of the permittivity and permeability are all negative; the effect has largely enhanced the electromagnetic wave's resonance intensity, and has improved the localized extent of electromagnetic energy obviously in such medium, resulting in a higher antenna gain, a lower return loss, and a better improvement of the antenna's characteristics. Due to such advantages, the applications of patch antennas can be extended to such fields as mobile communication, satellite communication, aviation, etc.

Giant cross section of resonant electromagnetic wave scattering by electron in metal and semiconductor clusters

A new formula is obtained for the cross section of light scattering by electron under conditions where the damping of its oscillations is related entirely to the spontaneous re-radiation of photon. The cross section for resonant light scattering can become macroscopic, which is only possible in a nanocluster where the phonon energy is greater than the photon energy.

Left-Handed Effect of Composite Rectangular SRRs and Its Application in Patch Antennae

We concentrate on describing the important influence and physical law of the split resonant ring (SRR) based left-handed materials on patch antennae. The finite-difference time-domain method, together with the finite element method is used to study the characteristics of patch antennae based on composite rectangular SRRs. A novel composite rectangular SRR system is formed by assembling the conventional patch antennae and SRRs, it is found that electromagnetic wave resonance occurs near f = 3.15 GHz, the equivalent permittivity and permeability are both negative, and the electromagnetic wave's tunnel effect and evanescent waves' enhancing effect are formed, which can improve the localization extent of electromagnetic wave's energy apparently. Such effects can improve the antenna's radiation gain and its matching condition. The phenomenon indicates that such composite rectangular patch antennae are promising in wireless communications such as mobile phones, satellite communication and aviation.

Superfluorescent pulsed emission from biexcitons in an ensemble of semiconductor quantumdots

Picosecond time-resolved photoluminescence from biexcitons in CuCl quantum dots(QDs) embedded in a NaCl matrix has been measured using an optical Kerrgate method. Ultrafast pulsed emission from the biexciton states was observedfor the first time, only under resonant two-photon excitation of biexcitons. Thisimplies that complete population inversion between the biexciton and excitonstates is necessary in order to trigger the pulsed emission. In addition, the natureof the dependence of the time profiles of the pulsed emission on the excitationintensity reveals that the peak intensity is directly proportional to the square ofthe number of excited QDs. We conclude that this phenomenon is caused bysuperfluorescence, that is, the cooperative spontaneous radiative decay of many isolatedexcited states coupled by a resonant electromagnetic wave. Such a phenomenon hasbeen observed for the first time in an ensemble of semiconductor QDs in thisstudy. The results presented in this paper show that it is possible to control themicroscopic coherent dynamics of electronic excited states in a QD ensemble.