TE-polarized Waves Research Articles

A 2-D Fully Polarized Van Atta Array Based on Wide-Beam Tri-Polarized Antennas.

This paper proposes a 2-D fully polarized Van Atta array, which consists of four tri-polarized antenna elements. The tri-polarized antenna element comprises a monopole antenna and a low-profile microstrip antenna that widens the beam by folding four electric walls. This configuration enables the Van Atta arrays to receive and transmit arbitrarily polarized incident waves over a wider range. The measurement results indicate that the proposed Van Atta array exhibits a -5 dB radar cross-section (RCS) greater than 95° when TE-polarized waves are incident and greater than 134° when TM-polarized waves are incident, significantly surpassing the 2-D dual-polarized array.

Enhancement of transverse magneto-optical Kerr effect using transition metals in a grating-based gyro-electric structure

Abstract This study proposes a new structure based on a grating with magneto-optical properties and a layer of transition metals (platinum, silver, copper, gold, and palladium). The research aims to investigate the impact of surface plasmon polaritons on enhancing the transverse magneto-optical Kerr effect when exposed to TM- and TE-polarized waves. After optimizing the structure’s dimensions, it was determined that the transition metal layer should have a thickness of 20 nm. The study involves applying TM- and TE-polarized light to the structure to observe variations in reflected light and the transverse magneto-optical Kerr effect. The findings reveal that the gyro-electric magneto-optics material responds to TMpolarized waves, and silver and gold are identified as the most effective metals for the proposed structure.

A bidirectional broadband multifunctional terahertz device based on vanadium dioxide

We propose a switchable and bidirectional metamaterial terahertz absorber/reflector based on vanadium dioxide. Simulation results show that the device can achieve broadband absorption and reflection by adjusting the phase state of vanadium dioxide. When the vanadium dioxide is in the insulating phase, the device can be a perfect bidirectional broadband absorber with more than 90% absorptivity under normal forward/backward TE/TM-polarized incident wave in the frequency range from 1.9 THz to 10 THz. This excellent absorption characteristic is insensitive to the polarization angle of the incident wave. When the vanadium dioxide is in the metal phase, the device achieves more than 90% reflectivity in the low-frequency range under forward/backward TE-polarized incident wave. In the high-frequency range, the device has both reflection and absorption effects on the TE-polarized wave. When vanadium dioxide is in two different phase states, the performance of device is not sensitive to the electromagnetic wave incidence angle. The change in vanadium dioxide conductivity does not affect the stable performance of the device at high (low) frequencies when used as an absorber (reflector). The proposed device has potential applications in terahertz energy harvesting, detection, sensing, optical switching, and shielding.

Revisiting optical absorption power density of inhomogeneous plane waves

We review the analytical expressions for the complex Poynting’s vector in the case of arbitrary plane-waves in a lossy isotropic medium. We demonstrate how these expressions can be used to recover the optical absorption power density Q, considering the divergence of the time-averaged Poynting vector. This quantity, proportional to the imaginary part of the dielectric function and the field intensity, i.e. Q∝|E|2ɛ”, is usually established for harmonic fields, using the Poynting’s identity. The derivation from the complex Poynting vector expression is more direct for TE-polarized homogeneous waves, but the derivation encompasses the other cases like inhomogeneous TM plane waves. As an application, the optical absorption profile Q(x) within 1D multilayers is detailed using matrix transfer method for both TE and TM plane waves, including the evanescent case.

An ultra-wide-angle metasurface absorber operating in the ultraviolet to visible range

Here, we propose an ultra-wide-angle metasurface absorber. It consists of a one-dimensional titanium grating periodic array with dislocation distribution. The average absorptivity of the absorber exceeds 94% in the ultraviolet to visible light band (200–760 nm) under normal TM-polarized incident wave. This benefits from the coupling of propagating surface plasmon resonance, local surface plasmon resonance, and hybrid mode resonance. For normal TE-polarized incident wave, the absorber achieves perfect narrowband absorption (>99.22%) in the ultraviolet light region because of the excitation of cavity-mode resonance. The absorber exhibits broadband absorption with an average absorptivity exceeding 85% in the visible light band because of the excitation of slot mode. These excellent absorption properties are well retained at 70° oblique incidence. The structural symmetry of the absorber dramatically expands the flexibility of device applications. It can achieve great absorption performance in an ultra-wide-angle range of 280° along the incident light direction. In addition, the absorber is sensitive to the polarization angle and incident angle of ultraviolet light, which can be used for ultraviolet detection and sensing. The proposed ultra-wide-angle metasurface absorber has potential application in the field of optical communication, photoelectric detection, and solar energy harvesting.

Heuristic solution to the problem of diffraction of a TE-polarized electromagnetic field on a half-plane with generalized two-sided impedance boundary conditions

Employing the method of fundamental components, heuristic formulas are constructed for solving the problem of diffraction on a half-plane with non-ideal boundary conditions. The problem of diffraction of a TE-polarized wave on a half-plane with generalized two-sided impedance boundary conditions was chosen as a verification solution. The accuracy was increased by two types of adjustment functions. The effectiveness of the applied technique is proven by quantification of accuracy. This approach represents a new way to obtain high-accuracy heuristic formulas and allows one to create solvers that simultaneously have both high accuracy and high performance. The main result is the development and description of adjustment methods for increasing the accuracy of heuristic formulas.

Compact polarization beam splitter based on metal-capped thin-film LiNbO3-on-insulator plasmonic waveguide

A compact polarization beam splitter based on a triple-waveguide plasmonic directional coupler is proposed and modeled. The directional coupler consists of two usual lithium-niobate-on-insulator (LNOI) ridge waveguides and a metal-capped plasmonic LNOI waveguide located between them. It utilizes stronger polarization dependence of modal birefringence of a plasmonic waveguide. By appropriately designing the plasmonic waveguide geometry, the TM component wave meets the resonant coupling condition and outputs at cross port. Instead, the TE component wave does not meet the resonant coupling condition, cannot be resonant in the triple-waveguide directional coupler and outputs at through port directly. Excellent performance is expected for an optimal device. First, the device shows an ultra-high polarization extinction ratio(PER) of 28.3 dB and an ultra-low insertion loss(IL) of 0.06 dB for the TE-polarized wave, and of 31.7 dB and of 0.31 dB in order for the TM-polarized wave. Second, the working bandwidth with PER > 25 dB and IL < 0.08 dB is 100 nm (1500–1600 nm) for the TE-polarized wave, and that with PER > 20 dB and IL < 0.4 dB is 30 nm (1534–1564 nm) for the TM-polarized wave. Third, the device has a compact structure of 33 μm in length and exhibits definite fabrication tolerance. Overall, the proposed device exhibits ultra-high PER and ultra-low IL, and has a compact size suitable for on-chip use. A comparison shows that present device exhibits advantage in IL and/or size over that based on other LNOI structures or the SOI platform.

On the Existence of an Infinite Spectrum of Damped Leaky TE-Polarized Waves in an Open Inhomogeneous Cylindrical Metal–Dielectric Waveguide Coated with a Graphene Layer

We consider the problem of leaky waves in an inhomogeneous waveguide structure covered with a layer of graphene, which is reduced to a boundary value problem for the longitudinal components of the electromagnetic field in Sobolev spaces. A variational statement of the problem is used to determine the solution. The variational problem is reduced to the study of an operator function. The properties of the operator function necessary for the analysis of its spectral properties are investigated. Theorems on the discreteness of the spectrum and on the distribution of the characteristic numbers of the operator function on the complex plane are proved.

Numerical Study of the Spectrum of TE-Polarized Electromagnetic Waves of a Goubau Line Coated with Graphene

Numerical Study of the Spectrum of TE-Polarized Electromagnetic Waves of a Goubau Line Coated with Graphene

Electromagnetic Guided Wave in Goubau Line with Graphene Covering: TE Case

This paper focuses on the problem of monochromatic terahertz TE-polarized wave propagation in a special type of circle cylindrical waveguides, the so-called Goubau line. The outer shell of the waveguide is covered with graphene characterized by complex surface conductivity. This covering affects electromagnetic wave propagation due to the generation of a surface current in graphene. The nonlinear interaction of graphene with the electromagnetic field is taken into account via a nonlinear term involving in graphene conductivity. Starting from the rigorous formulation for Maxwell’s equations with appropriate boundary and transmission conditions, we derive the dispersion equation for propagation constants. We discuss this result and point out some methods of studying the dispersion equation analytically. At the same time, we suggest numerical experiments shedding light on how cubic nonlinearity affects electromagnetic wave propagation.

Dispersion-boosting wideband electromagnetic transparency under extreme angles for TE-polarized waves.

Half-wave wall is the most common method of achieving electromagnetic (EM) transparency. Transmission windows can be formed when reflected waves are out of phase. Due to the interference mechanism, these windows are dependent on the frequency and incident angle of EM waves, leading to limited bandwidth, especially under extreme angles. In this letter, we propose to extend the bandwidth of the transmission window under extreme angles by utilizing dispersion. To this end, long metallic wires are embedded into the half-wave wall matrix, without increasing the physical thickness. Due to the plasma-like behavior of metallic wires under TE-polarization, the effective permittivity of the half-wave wall, rather than keeping constant, increases with frequency nonlinearly. Such a dispersion will boost wideband transparency in two aspects. On one hand, an additional transmission window will be generated where the effective permittivity equals that of the air; on the other hand, the 1st- and 2nd-order half-wave windows will be made quite closer. By tailoring the dispersion, the three windows can be merged to enable wideband transparency under extreme incident angles. A proof-of-principle prototype was designed, fabricated, and measured to verify this strategy. Both simulated and measured results show that the prototype can operate in the whole Ku-band under incident angle [70°, 85°] for TE-polarized waves. This work provides an effective method of achieving wideband EM transparency under extreme angles and may find applications in radar, communications, and others.

Ultrawide-Angle Broadband Electromagnetic Window for Both TM- and TE-Polarizations by Synergy of Multimechanism Resonances

As protective apparatus, electromagnetic windows (EMWs) are usually realized utilizing dielectric materials with higher permittivity or larger thickness to perform good mechanical properties. However, due to impedance mismatch, higher insertion loss is inevitably created, especially at large incident angles. It is now still a great challenge to engineer EMWs with stable operating bands and a wide range of incident angles for both transverse electric (TE)-and transverse magnetic (TM)-polarizations. In this article, we propose a method to achieve such EMWs by the synergy of multimechanism resonances, which enables broadband transmissions of both TM-and TE-polarized waves in an ultrawide range of incident angles. Fano resonance is first introduced to expand the bandwidth for TE-polarization on the basis of thickness resonance. Drude resonances are then introduced to suppress adverse influences of the parasitic Lorentz resonance for TM-polarization, to maximize the shared transmission band for TM-and TE-polarizations. The ultrawide-angle broadband functionalities of this EMW are validated by experiments, which agree well with numerical simulations. This work provides an efficient route to realize practical high-performance EMWs, under sufficient consideration of available materials, structures, and fabrication techniques, which may find wide applications in radar, communication, and imaging systems.

On the Existence of an Infinite Spectrum of Damped Leaky TE-Polarized Waves in an Open Inhomogeneous Cylindrical Metal–Dielectric Waveguide Coated with a Graphene Layer

On the Existence of an Infinite Spectrum of Damped Leaky TE-Polarized Waves in an Open Inhomogeneous Cylindrical Metal–Dielectric Waveguide Coated with a Graphene Layer

The Nonlinear Eigenvalue Problem of Electromagnetic Wave Propagation in a Dielectric Layer Covered with Graphene

The paper focuses on the problem of a monochromatic terahertz TE-polarized wave propagation in a plane dielectric layer filled with a homogeneous isotropic medium; one of the boundaries of the waveguide is covered with a layer of graphene. In fact, the paper aims to find the eigenwaves of the described waveguiding structure. On the one hand, in the study, energy losses both in the dielectric layer and in the graphene layer are neglected; the latter assumption is reasonable in the terahertz range of electromagnetic radiation (on which the paper focuses), where graphene has a strong plasmonic response and much less loss. On the other hand, this study takes into account the significant third-order nonlinearity resulting from the interaction of the electromagnetic wave with the charge carriers in the graphene layer. The paper aims to study the guiding properties of the above structure using primarily an analytical approach. The wave propagation problem is reduced to an eigenvalue problem, where one of the boundary conditions is nonlinear with respect to the sought-for function. The main result of the paper is a dispersion equation allowing for a waveguide of a given thickness to determine a set of its propagation constants and, consequently, a set of its eigenwaves. It is worth noting that the dispersion equation being written in an explicit form can be used to obtain deep qualitative results related to the solvability of the problem and the properties of its solutions. For example, in the paper, the existence of several propagation constants (and, consequently, the eigenwaves) of the studied waveguiding structure is proved under some conditions. Besides studying the problem analytically, the paper presents some numerical results as well. In particular, the presented figures demonstrate how the nonlinearity in graphene affects the propagation constants and eigenwaves, providing the dispersion curves and eigenwaves for nonlinear graphene as well as for the linear one.

All-dielectric metasurface based ultranarrow bandpass filter in optical C-band

Metasurface-based nanophotonics devices can potentially replace traditional bulky optical components such as optical filters, modulators, and switches. In this study, we report a dielectric metasurface-based ultranarrow bandpass filter operating at 1549.8 nm with the ability to tune the central wavelength within the C-band. The proposed tunable filter consists of a 2D periodic array of gallium arsenide blocks placed on top of a quartz substrate. The introduction of a symmetry-breaking defect results in an ultranarrow resonance with an FWHM of 0.31 nm at a 1549.8 nm wavelength when a TE-polarized wave is normally incident. The sharp, high Q factor resonance is understood to be governed by the symmetry-protected bound state in the continuum. The resonant response can be tuned by changing the periodicity, thickness, and asymmetry of the metasurface constituents. The multipolar analysis indicates the excitation of the electric quadrupole mode at the resonance wavelength. Our findings can be useful for the design of compact tunable ultranarrow bandpass filters for optical communications systems.

TE-Polarized Electromagnetic Wave Diffraction by a Circular Slotted Cylinder

The problem of diffraction of a TE-polarized electromagnetic wave by a circular slotted cylinder is investigated. The boundary value problem in question for the Helmholtz equation is reduced to an infinite system of linear algebraic equations of the second kind (SLAE-II) using integral summation identities (ISI). A detailed study of the matrix operator of the problem is performed and its Fredholm property in the weighted Hilbert space of infinite sequences is proven. The convergence of the truncation method constructed in the paper for the numerical solution of SLAE-II is justified and the results of computations are presented and discussed, specifically considering the determination of resonance modes.

Simulated Studies of Polarization-Selectivity Multi-Band Perfect Absorber Based on Elliptical Metamaterial with Filtering and Sensing Effect

In this work, the Ag-SiO2-Ag metamaterial with elliptical nano-slits was proposed to investigate the multi-band polarization-dependent perfect absorber. It was found that multi-band perfect absorptions can be induced under TE and TM-polarized illuminations. Simulation results showed that the absorption peaks for TE-polarized wave appeared at 337.6 THz and 360.0 THz with 98.5% and 97.6% absorbance, respectively. Conversely, the absorption peaks for TM-polarized wave appeared at 325.7 THz and 366.1 THz with 96.3% and 97.9% absorbance, respectively. As a result, the elliptical metamaterial presented polarization-selectivity property for perfect absorption, and so, the metamaterial can filter out different frequencies of TE- and TM-reflected waves, i.e., the elliptical metamaterial can be used as a reflecting filter. In addition, this work studied the sensing performance of the elliptical metamaterial and showed that the dual-band sensing performances were different at low and high frequencies. The sensitivities (S) to the refractive index reached up to 151.1 THz/RIU and 120.8 THz/RIU for the TE and TM-polarized waves around 337.6 THz and 325.7 THz, which provide promising potential in near-infrared photoelectric sensor and detector. However, both the absorption frequency and intensity of TM-polarized wave were insensitive to the refractive index of the medium around 366.1 THz, and so, the study provides a theoretical basis for infrared stealth of different media.

Modeling of narrow beams of electromagnetic waves with axial symmetry on a plane

A mathematical model of narrow beams of monochromatic electromagnetic waves propagating in vacuum is developed. Beams of electromagnetic waves are constructed with the order of axial symmetry m m( 0,1, 2, ), = K characterized by the beam localization radius Rпуч, the beam narrowness parameter n n( 2), ≥ and the beam attenuation coefficient N N( 2). ≥ The structure of the electric field for a TE-polarized wave beam is studied numerically.

Refinement of the Heuristic Solution for the Problem of TE-Polarized Electromagnetic Wave Diffraction on a Half-Plane with Two-Sided Impedance Boundary Conditions

A technique for obtaining refined heuristic solutions for problems with electromagnetic wave diffraction by scatterers with non-ideal boundary conditions is proposed. Based on the method of fundamental components for the problem of TE-polarized wave diffraction on a “semitransparent” half-plane with two-sided impedance boundary conditions, an improved heuristic solution for the scattered field is obtained by replacing the primary heuristic formula. A quantitative and qualitative assessment of the accuracy of the heuristic relationship is carried out as well as a physical interpretation of the rigorous solution based upon them. A classification of heuristic solutions is proposed according to the purpose of their application in practical problems.

Investigation of reflection bands of 1D annular photonic crystal containing double negative index material and non-magnetized plasma

In this paper, optical reflectance properties of an annular photonic crystal (APC) composed of alternate layers of double negative (DNG) material and a non-magnetized plasma (NMP) layer, immersed in free space, have been theoretically investigated and studied. The reflectance spectra of the annular PC have been obtained by employing the transfer matrix method (TMM) for the cylindrical waves in the case of TEpolarized wave only. It has been found that the spectral position and width of the reflection bands of APC are greatly influenced by the variation in the thickness of DNG metamaterial and NMP layer, respectively. Interestingly, it is observed that the presence of NMP layer causes the increase in photonic band gap (PBG) whereas the DNG layer reduces the PBG. Further, the effect of azimuthal mode number (m) on the reflectance spectra shows that for m &gt; 0, splitting in the reflection bands occurs at the frequency corresponding to the zero permeability value of DNG metamaterial layer. Moreover, with the increase in azimuthal mode number one PBG is red-shifted and the second one is blue-shifted. Finally, the effect of change in the starting radius parameter of curved surface and plasma electron density on the reflectance spectra of APC has also been studied and very interesting results have been observed.