Transmission Properties Of Electromagnetic Wave Research Articles

Singular transmission properties of electromagnetic waves in one-dimensional [formula omitted]-symmetric triangular optical waveguide networks

In this paper, the singular transmission properties of electromagnetic waves in one-dimensional PT-symmetric triangular finite periodic optical waveguide networks are investigated. We find that the transmission properties of electromagnetic waves differ significantly depending on whether the imaginary part of the system’s Bloch phase is zero or non-zero. Based on this, the generalized passbands and bandgaps of the PT-symmetric optical waveguide network are defined, and its generalized band structure is presented. Furthermore, we discover that electromagnetic waves incident within the frequency range of generalized bandgaps, where transmittance approaches zero, exhibit a reciprocal relationship between left and right reflectance. The system can generate interesting phenomena such as bidirectional total reflection, unidirectional super reflection, and unidirectional no reflection at these frequencies. It is also demonstrated that the frequency positions of these phenomena can be flexibly controlled by adjusting the length of the PT-symmetric waveguide and the imaginary part of its refractive index. These research findings offer a scientific basis for developing highly sensitive and multifunctional optical filters and laser reflectors.

Phase‐Coupling‐Induced Far‐Field Modulation between Nontrivial and Trivial Modes in Cavity–Waveguide Systems

Photonic crystal (PhC) can be accurately designed to generate nontrivial and trivial modes, that is, edge states (ES)/corner states (CS) and cavity modes, respectively. The coupled cavity–waveguide system designed by PhC provides a chip‐scale platform to manipulate electromagnetic (EM) waves that is usually based on near‐field coupling between nontrivial and trivial modes. However, the far‐field interaction between nontrivial and trivial modes for manipulating EM waves has not attracted wide attention yet. Herein this article, the coupled cavity–waveguide systems, which consist of two separated CS cavities (interacting with single/multiple trivial cavity/cavities) coupled by means of an ES waveguide, are designed to robustly tune the transmission properties of EM waves by modulating the phase coupling between CS cavities. As proof‐of‐principle examples, single‐, dual‐, and triple‐electromagnetically‐induced‐transparency‐like (EIT‐like) phenomena with tunable transmission spectra are theoretically and numerically demonstrated by controlling the distance (generated phase accumulation) between the CS cavities. In addition, the robustness in generating EIT‐like transmission characteristics is also demonstrated due to the robustness of the CS cavities. The unique cavity–waveguide systems with unprecedented capability in robustly tuning the transmission spectra of EM waves can be extended to design other high‐performance devices with potential applications in sensing, detecting, and information processing.

A Comparative Study of the Transmission Properties of Electromagnetic Waves in Inhomogeneous Dusty Plasma

A Comparative Study of the Transmission Properties of Electromagnetic Waves in Inhomogeneous Dusty Plasma

A dual-broadband h-shaped metasurface for cross-polarization and asymmetric transmission with high stable incidence angle

This letter presents a bi-layered chiral metasurface to achieve angularly stable dual-broadband cross-polarization conversion and asymmetric transmission properties of electromagnetic waves with linear polarization. In this regard, any unit cell of the recommended chiral metasurface consists of two new h-shaped resonators configured on two opposite sides of a dielectric slab. Investigations of the simulated and experimental electromagnetic responses validate that the impinging x − (y−) and y − (x−) polarized waves can convert into transmitted y − (x−) and x − (−y) polarized waves at 7.5–8.6 GHz and 15–16.6 GHz, if the incident waves pass through the structure along −z (+z) direction, respectively. The obtained polarization conversion ratio (PCR) and asymmetric transmission parameters are more than 0.9 and 0.55 at both operated frequency bands, sequentially. Therefore, the proposed CMS has a significant potential to transform x- and y- polarized waves to orthogonal ones over the related frequency bands. The mechanism of the polarization conversions for any incident polarized wave has been verified by studying surface current distributions.

Transmission enhancement effect of electromagnetic wave in non-uniform collisional plasma

The effect of plasma on the transmission properties of electromagnetic waves and its application have always been one of the key research directions of electromagnetic theory and technology and plasma physics. The enhancement effect of collisional plasma on electromagnetic waves is a classic subject of the interaction between electromagnetic waves and plasma. Based on the transmission characteristics of electromagnetic waves in medium, this paper takes plasma as a special medium, and carries out experimental, theoretical and simulation studies on the transmission characteristics of high power microwave (HPM) atmospheric plasma and a certain range of electromagnetic waves under certain experimental conditions. The study found that the plasma formed by the S-band HPM under a vacuum of 50 Pa has a great influence on the electromagnetic wave transmission characteristics of different frequencies, and the electromagnetic wave transmission signal enhancement effect occurs regularly within a certain frequency range. A series of transmission waveforms of continuous electromagnetic waves of different frequencies passing through the HPM plasma area were obtained, and the waveforms were normalized. At 32.4 GHz, the transmission coefficient of continuous electromagnetic waves passing through the plasma area with plasma is about twice as high as that through the area without plasma. A simulation model was established, and the transmission coefficient distribution curve in the range of 31.5−32.5 GHz was obtained. The electromagnetic wave passing through the plasma showed a transmission enhancement effect, and at some frequency points, there was a transmission enhancement of about 1.9 times. The research results provides important technical support for the application of plasma in stealth, emergency communications, and black barrier communications.

Transmission properties of electromagnetic waves in piezoelectric photonic crystal with periodically reversed ferroelectric domains

We design the piezoelectric photonic crystal (PPC) with periodically reversed ferroelectric domains on the base of the structure of the piezoelectric superlattice, and study theoretically the transmission properties of electromagnetic (EM) waves in the PPC through Transfer Matrix Method of the photonic crystal (PhC). We analyze the mechanism for the influence of the piezoelectric effect on the transmission properties of EM waves in the PPC. The piezoelectric effect can influence the transmission properties of EM waves by changing the dielectric properties of the PPC. And we discuss the difference between the PPC and PhC. In the low frequency region, the reflection spectrum of PPC appear the total reflection and zero refractive indexes, and which doesn't exist in the PhC. In the high frequency region, the frequency positions and widths of the photonic band gaps of the PPC are higher and wider than cases of the PhC, respectively. Some potential applications are also discussed.

Extrinsic magnetized plasma Fabry–Perot resonator

This study uses the transfer matrix method to compute the transmission properties of electromagnetic waves within the microwave region of the one-dimensional extrinsic magnetized plasma periodic multilayer. The layer thicknesses of the extrinsic photonic structure were determined by the spatially varying external magnetic field. Apart from a few photonic bandgaps, a cluster of the resonant peak was noticed within the microwave region in the absence of a defect layer. The envelope of such resonant peaks was controlled by changing the layer’s thickness, the strength of the external magnetic field and the electron density of the magnetized cold plasma. With these features, periodic extrinsic magnetized plasma photonic crystal would offer a potential for designing a tunable multi-resonance periodic multilayer Fabry–Perot resonator for microwave applications.

Enhanced transmission by a grating composed of left-handed materials

We present a detailed theoretical analysis about the influence of surface polaritons on the transmission properties of electromagnetic waves at the periodically corrugated interface between the vacuum and left-handed material by using nonlinear boundary condition approach. The principle behind this approach is to match the wave fields across the grating interface by using a set of linear wave equation with nonlinear boundary conditions. The resonant transmission of the incident electromagnetic radiation in this structure is feasible within a certain frequency band, where there is a range of frequency over which both the electric permittivity and the magnetic permeability are simultaneously negative. The enhanced transmission is attributed to the coupling of the incident electromagnetic wave with the excited surface polaritons on grating interface. Finally, we present the numerical results illustrating the effect of the structural parameters and angle of incidence on the transmission spectra of a TM polarized electromagnetic wave.

Effect of standard deviation, strength of magnetic field and electron density on the photonic band gap of an extrinsic disorder plasma photonic structure

Transmission properties of electromagnetic waves within microwave region of the one-dimensional random extrinsic plasma photonic crystals were computed using the transfer matrix method. The layers thicknesses of the extrinsic random photonic structure follow a Gaussian distribution. Compared with the periodic extrinsic photonic crystal, wider photonic band gaps (PBGs) were found in case of random extrinsic plasma photonic crystals with few resonant peaks. The PBGs are much wider while the randomness was increased and the number and the strength of resonant peaks were enhanced. The above observations were confirmed through analysis of histogram of normalized average transmissions for four different values of standard deviation with one thousand random samples for each group. The normalized average transmission was controlled by changing the strength of external magnetic field and the electron density of magnetized cold plasma. These features of disordered extrinsic plasma photonic structures would have potential applications such as omnidirectional reflectors and random multichannel filters with lower and higher rate of disorder.

Transmission Properties of Electromagnetic Wave in Pre-Cantor Bar: Scaling and Double-Exponetiality

Transmission Properties of Electromagnetic Wave in Pre-Cantor Bar: Scaling and Double-Exponetiality

Absorption effects on the longitudinal bulk plasmon–polariton modes in 1D heterostructures containing anisotropic metamaterials

The transmission properties of electromagnetic waves through a one-dimensional layered system containing alternate layers of air and a uniaxial anisotropic left-handed material are investigated. The optical axis of such heterostructure is along the stacking direction and the components of the electric permittivity and magnetic permeability tensors that characterize the metamaterial are modeled by a Drude-type response and a split-ring resonator metamaterial response, respectively. Different plasmon frequencies are considered for directions parallel and perpendicular to the optical axis. For oblique incidence, longitudinal bulk-like plasmon polariton modes are found in the neighborhood of the plasmon frequency along the optical axis and anisotropy leads to the unfolding of nearly dispersionless plasmon–polariton bands either above or below the plasmon frequency. Moreover, it is shown that, even in the presence of loss/absorption, these plasmon polariton modes do survive and, therefore, should be experimentally detected.

Bandgap properties of diamond structure photonic crystal heterostructures with inclined and curved interfaces

The 3D (dimensional) diamond structure photonic crystal heterostructures with different lattice constants were prepared using rapid prototyping and gel casting with alumina. In this paper, heterostructures with inclined and curved interfaces were designed and its bandgap properties were studied. The normalized resonant intensity of electromagnetic wave in heterostructure with inclined and curved interface is stronger than that in the ordinary heterostructure without modified interface. The influence of curved interface on transmission properties of electromagnetic wave was investigated with the radius of curvature ranging from 17 mm to 37 mm at 5 mm interval. The results show that two resonant modes appear in the photonic band gap, being similar to the band gap characteristics of the photonic crystals with two defects inside. With the increasing of the radius of curvature, the resonant mode shift to higher frequency. In the structure with a radius of curvature of 32 mm, a guiding band appears in the photonic band gap. Further increase in the radius of curvature, the guiding band will split into two resonant modes again and the two resonant modes shift to lower frequencies.

Ultra-Wideband Multi-Frequency Terahertz Square Microstrip Patch Antenna on Hybrid Photonic Crystal Substrate

In this paper, two-dimensional photonic crystals working at terahertz frequency is investigated, and an ultra-wideband terahertz microstrip patch antenna on hybrid photonic crystal substrate is presented. Microwave Studio software is used to simulate its electromagnetic wave transmission properties. The proposed antenna can work at six frequency points' scope at terahertz frequency regions, and the 10 dB bandwidth is higher than ∼59%. The hybrid photonic crystal structure is able to provided ultra wide stop-band spectrum, in addition to advantages of the traditional photonic crystal structure which can enhance the gain, directivity and radiation efficiency of the antenna.

Modulation of Optical Transmission in Photonic Crystal

The transmission properties of electromagnetic wave (EMW) can be modulated by the periodic structure of photonic crystal (PhC) to bring many novel optical effects. The special distributions of equal frequency contours (EFCs) can be used to control the wavefront state and transmission direction of propagating wave in PhC with some special effects, such as non-handed refraction. Based on the intricate undulation of one single band or the overlap of different bands, the phenomena of dual-negative refraction, symmetrical positive-negative refraction and triple refraction have been achieved in the higher band regions. These unique features will provide us with more understanding of electromagnetic wave propagation in PhCs and give important guideline for the design of new type optical devices.

Transmission Properties of Electromagnetic Waves Through Left-handed Material: A Revisit

The transmission properties of electromagnetic wave through left-handed material (LHM) have been thoroughly investigated. The characterization of signal propagation and evanescent wave amplification through LHM slab has been done on the basis of analytical model equations. The transmission properties have also been addressed from the study of group and phase indices, and anomalous dispersions regions in LHM and right-handed material. Furthermore, the orthogonality of electric and magnetic fields of classical electromagnetism has been seen to be applicable for electric and magnetic plasma buffered by a left-handed (LH) medium.

Theoretical and experimental studies of electromagnetic wave transmission in plasma

The aircrafts, such as space shuttle, spaceship and so on, are facing the well-known blackout problem when they reentry into the atmosphere. The plasma sheath leads electromagnetic waves to attenuation, and the communications between the aircrafts and the ground to losing, and even completely interrupte, thereby resulting in the loss of radar targets and threatening the lives of the astronauts. Therefore, it is important to study the properties of the electromagnetic wave transmission in plasma. The characteristics of electromagnetic wave transmission in plasma are studied theoretically and experimentally in this paper. The variations of the electromagnetic wave attenuation with plasma density, collision frequency and electromagnetic wave frequency are obtained. The electromagnetic wave attenuation increasean an order of magnitude with plasma density increasing an order of magnitude. The electromagnetic wave attenuation first increases and then decreases with plasma collision frequency increasing, the electromagnetic wave attenuation decreases with the increase of electromagnetic wave frequency. The electromagnetic wave transmission properties in plasma are studied experimentally with shock tube, and the experimental results accord well with the theoretical results. The results show that increasing the electromagnetic wave frequency is an effective way to solve the reentry blackout problem.

Experimental Study on the Interaction of Electromagnetic Waves and Glow Plasma

An experimental system was established in order to study the interaction between electromagnetic waves, with a frequency of 300 kHz to 3 GHz, and DC glow discharge plasma. The results show that the DC glow discharge plasma affects the transmission properties of electromagnetic waves, while the waves can change both temperature and density of electrons.

Thermal radiative properties of metamaterials and other nanostructured materials: A review

The ability to manufacture, control, and manipulate structures at extremely small scales is the hallmark of modern technologies, including microelectronics, MEMS/NEMS, and nano-biotechnology. Along with the advancement of microfabrication technology, more and more investigations have been performed in recent years to understand the influence of microstructures on radiative properties. The key to the enhancement of performance is through the modification of the reflection and transmission properties of electromagnetic waves and thermal emission spectra using one-, two-, or three-dimensional micro/nanostructures. This review focuses on recent developments in metamaterials-manmade materials with exotic optical properties, and other nanostructured materials, such as gratings and photonic crystals, for application in radiative energy transfer and energy conversion systems.

Investigation of fracture flow paths using alterant geophysical tomography

The mapping of fractures is a problem of major importance to many geotechnical projects. It is a three dimensional problem requiring the use of measurement methods with sufficient resolution and probing range to map fractures at a distance from exposed surfaces. The National Research C6uncil's report on Rock Mechanics Research Requirements [1] identified a need for major improvements in the methods used for mapping remote fractures. This article discusses a new geophysical method (Alterant Geophysical Tomography, AGT) in which tracers are forced into the in situ rock fractures to change the transmission properties of electromagnetic waves propagated between boreholes or tunnels. The theoretical advantages of the method and the results of the first experiment where it was used are also presented. This technique is analogous to the medical diagnostics technique known as X-ray fluoroscopy wherein a tracer is used to attenuate X-rays. The movement of the tracer within the digestive tract or circulatory system of the human body is monitored by measuring the attenuation of X-rays. AGT involves the transmission of an electromagnetic energy field through fractured rock before, during, and/or after a tracer is forced into the fractures. By using alterant geophysical tomography, changes induced by these tracers are mapped in the plane defined by the two boreholes. This approach is intended for geologic environments where fracture flow dominates such that the tracer penetrates the fractures but not the rock matrix.

Reflection and transmission of electromagnetic waves by a semi‐infinite uniaxial plasma moving perpendicular to the plane of incidence

The reflection and transmission properties of electromagnetic waves by a semi‐infinite uniaxial plasma moving perpendicular to the plane of incidence are investigated theoretically for the incident H and E plane wave. In this case, the plasma becomes anisotropic, and electromagnetic field components of the transmitted wave should be hybrid modes. Thus it is shown that the behavior of the power reflection coefficient is remarkably different from that of a stationary one.