Polarization Of Electromagnetic Wave Research Articles

All-dielectric achromatic hole-array metasurfaces

Metalens, an ultra-thin optical element composed of subwavelength structure, offers a new path for the development of miniaturized device imaging. Through the design of subwavelength units, arbitrary modulation of the phase, amplitude, and polarization of electromagnetic waves can be achieved. However, current metalenses generally suffer from the disadvantages of narrowband and Ohmic losses, which limits the development of high-quality imaging. In this work, using all-dielectric hole-array structure within the framework of effective medium theory, we demonstrate the achromatic focusing effect based on the basic Huygens principle. Moreover, by changing the position of the point source, this metalens can also achieve directional refraction with flexible angles. Our results provide a new solution for the practical application of miniaturized integrated high-quality imaging, and may open up avenues for constructing efficient artificial metasurface with metamaterials for energy harvesting and other wave manipulation.

Mueller Matrix Polarizing Power

The transformation of the states of polarization of electromagnetic waves through their interaction with polarimetrically linear media can be represented by the associated Mueller matrices. A global measure of the ability of a linear medium to modify the states of polarization of incident waves, due to any combination of enpolarizing, depolarizing and retarding properties, is introduced as the distance from the Mueller matrix to the identity matrix. This new descriptor, called the polarizing power, is applicable to any Mueller matrix and can be expressed as a function of the degree of polarimetric purity and the trace of the Mueller matrix. The graphical representation of the feasible values of the polarizing power provides a general view of its main peculiarities and features. The values of the polarizing power for several typical devices are analyzed.

Genus Plasma-Based Self-Complementary Reconfigurable Intelligent Metasurfaces

AbstractThis paper investigates the radiation properties of plasma-based intelligent reflectarray surface (IRS) that utilizes self-complementary elements. The elements of the surface employ reconfigurable plasma conductivity to manipulate the polarization of electromagnetic waves in various Ka-band applications. The unit-cell of the IRS is composed of 2 × 2 sub-cells of 0.5 λo × 0.5 λo × 0.078 λo mm3. Each sub-cell contains three glass containers arranged in a triangle-rectangular-triangle configuration and filled with ionized plasma gas. When the IRS illuminated by a linearly polarized (LP) plane wave, the surface converts it into circularly polarized (CP) waves based on the plasma ionization state. It achieves dual-band polarization conversion at 7.3 GHz with bandwidth of 200 MHz and at 8.6 GHz with a bandwidth of 1.15 GHz. To enhance the polarization conversion bandwidth, a sequential arrangement of self-complementary unit-cell elements with different sizes is employed. An 8 × 8 genus reconfigurable IRS is utilized to generate both left-hand circularly polarized (LHCP) and right-hand circularly polarized (RHCP) waves from the upper and lower sides of the structure. The axial ratio (AR) bandwidth is maintained at 2.1 Hz for both surfaces. An LP horn antenna is used with the 8 × 8 genus reconfigurable IRS, resulting in a peak gain of 13.2 dBi, a side lobe level (SLL) of 6 dBi, and an AR bandwidth of 500 MHz. To further enhance the radiated gain, the ionized plasma within the self-complementary elements is controlled to focus the radiated power into a directive beam, resulting in an increased gain of 19.4 dBi.

A Self‐Powered Reconfigurable Intelligent Metasurface

AbstractIn recent years, reconfigurable intelligent metasurface (RIS) has gained much attention due to its flexibility in modulating the phase, amplitude, and polarization of electromagnetic waves. It is widely used for wireless power and information transmission. However, RIS requires an external wired power supply or batteries to activate their modulation capabilities, as they do not generate the required energy themselves. This paper presents a self‐powered RIS that does not require an external wired power supply or batteries. The modulation capability is activated by harvesting radio frequency (RF) energy. The self‐powered RIS consists of an energy‐metatom, which is loaded with a PIN diode for flexible phase modulation. The inclusion of an absorber/energy port on the energy‐metatom allows for independent RF energy harvesting. The RIS consisting of energy‐metatoms can cut out all wired power supplies and batteries so that it can dynamically regulate electromagnetic waves by self‐powered means. As a proof‐of‐concept, a prototype composed of 10 × 10 energy‐metatoms is fabricated. The measured results are in good agreement with the simulated. This self‐powered RIS can be used as an “infinite‐lifetime” power supply for dynamic electromagnetic modulation in the RIS.

Dual-band terahertz reflective-mode metasurface for the wavefront manipulation of independent linear and circular polarization waves

Metasurfaces (MSs) are being extensively researched owing to their ability to modulate the polarization and wavefront of electromagnetic (EM) waves in a flexible manner, which usually offer significant advantages including ultra-thinness, low losses, and easy fabrication. However, conventional MSs typically operate well only with a single polarization. Here, we propose a novel design strategy for a terahertz (THz) reflective-mode MS that relies on a single unit-cell arrangement combining propagation phase and geometric phase. Our designed MS can achieve multiple wavefront manipulations in reflection mode, not limited to circular polarization (CP) transformation, but also enabling linear polarization (LP) conversion. The MS we propose consists of a periodic array of bilayered metal patterned resonator structures sandwiched by a dielectric substrate. The metallic resonator is made of the outer single-split-ring (SSR) and C-shaped slot (CSS), inner double-split-ring (DSR), and its complementary structure. With this design, the MS is capable of converting a LP wave to its orthogonal counterpart at lower frequency (f1=0.7THz) after reflection. Additionally, at higher frequency (f2=1.4THz), the proposed MS can also convert the right-handed CP (RCP) to left-handed CP (LCP) upon reflection or vice versa. The 2π phase full coverage of the orthogonal LP and CP waves can be achieved independently and simultaneously by adjusting the opening and orientation angles of the SSR based on propagation phase, and orientation angle of the DSR based on geometric phase. We numerically demonstrate beam deflection, planar focusing, and the vortex beam for both reflected orthogonal LP and CP waves with three representative MSs to provide proof of concept. These findings reveal the great potential for multifunctional devices for dual-polarization in imaging and communication systems.

Wideband close perfect meta surface absorber for solar photovoltaic and optical spectrum applications

The leading research challenge is to develop a meta-surface absorber design for optimal performance across ultraviolet, visible, and near-infrared wavelengths. In ongoing research, a meta-surface absorber is being introduced, designed to achieve near-perfect absorption of 99% across the 250–2500 nm UV–Vis-NIR spectrum for both Transverse electric (TE) and Transverse magnetic (TM) polarized waves. The aimed design features a symmetrical resonator pattern, resulting in a polarization-insensitive absorption response. Additionally, the absorption response demonstrates robustness when altering the geometric parameters of the meta-surface unit cell. Precise simulation and modelling of the proposed meta-surface absorber are achieved by Employing a Finite Difference Frequency Domain (FDFD) solver, coupled with the Finite Integration Technique (FIT) and a tetrahedral mesh component. Verification of absorption characteristics is conducted through three frameworks: impedance matching, interference, and an equivalent circuit model. The suggested meta-structure design exhibits a uniform absorption response, as determined through considerations of impedance matching, interference theory, and the equivalent circuit theory. The PCR value is significantly lower than recent studies, reinforcing that the proposed meta-surface primarily serves as an absorber, not a polarization converter. The absorption response of the suggested meta-structure design remains consistent across the range of electromagnetic wave polarization angles from 0 to 90 for both TE and TM waves. Furthermore, the absorption response of the proposed design demonstrates stability up to an incident angle of 70 for electromagnetic waves. The distribution of electric and magnetic fields, along with surface current density on the proposed design, validates the existence of localized, propagating, and cavity surface plasmon resonance. These collectively create anti-parallel current flow, leading to the absorption of incident EM waves. Furthermore, the suggested design achieves a solar energy thermal conversion efficiency of 99% across the operational spectrum at a working temperature of 573 K, substantiating its potential for use as a solar absorber. Thus, this study presents a meta-structure unit cell that addresses the challenge with near-perfect absorption, polarization independence, and angle robustness. Applications include photodetection, thermal mapping, solar harvesting, and photo-trapping.

ОБҐРУНТУВАННЯ ПАРАМЕТРІВ МЕТОДУ РОЗРАХУНКУ ХАРАКТЕРИСТИК ЕЛЕКТРОМАГНІТНОГО РОЗСІЮВАННЯ МЕТАЛЕВОЇ НАНОЧАСТИНКИ У ОПТИЧНОМУ ДІАПАЗОНІ

Structures of nanoparticles of noble metals in the optical range are of great interest in solving practical problems of building and using optical antennas and sensors for communication, creating solar cells, coatings for masking objects in the optical range and their detection. Currently, intensive research is being carried out on resonance effects during the scattering and absorption of light by such nanosized particles. There are both experimental methods of studying the characteristics of electromagnetic scattering of nanostructures in the optical range, and methods of mathematical modeling. Mathematical methods are subject to strict requirements regarding accuracy and ensuring the convergence of calculation results. The method of integral equations is widely used to model scattering from various objects with finite dielectric constants. At the same time, in the optical range, scattering on nanoparticles, as homogeneous resonant objects, has its own characteristics that affect the accuracy and convergence of the calculation algorithm. The article examines the issue of choosing and justifying the parameters of the method for calculating the characteristics of electromagnetic scattering of nanoparticles of noble metals of different sizes in the optical range, which are based on the application of a system of Müller integral equations. The internal convergence of the algorithm for calculating electromagnetic scattering characteristics depends on the size and shape of nanoparticles. When calculating according to the proposed numerical method, the number of nodes in which the current density was calculated was chosen in such a way that there was an internal convergence of the algorithm characterized by a given value . The required number of current nodes and the discretization step on the surface of one nanoparticle of two sizes (75x75x25 and 100x100x20) were obtained, which ensure internal convergence and the best accuracy of the proposed computational algorithm. Nanoparticles of these sizes will be used as the basis for the construction of various structures. The direction of further research is obtaining and analyzing the characteristics of electromagnetic scattering of various structures made of silver nanoparticles under different conditions of irradiation and polarization of the incident electromagnetic wave.

Near‐Field Coupling Induced Less Chiral Responses in Chiral Metamaterials for Surface‐Enhanced Vibrational Circular Dichroism

AbstractChiral metamaterials play vital roles in manipulating the circular polarization of electromagnetic waves. Although planar chiral metamaterials are believed to have no true/intrinsic chirality, the design of structural anisotropy can still create enormous circular dichroism, while the mechanism is fully explored. Here, for the first time, it is observed that strong near‐field coupling induces less chiral response in chiral metamaterials. Selective exposure methods to manipulate the near‐field coupling strength, and experimentally validate the circular dichroism difference from tailored near‐field coupling effect are leveraged, which provides strong evidence for the assumption and can be utilized for the structural design framework. Besides, using the enhanced near‐field (over 750‐fold), surface‐enhanced vibrational circular dichroism (SEVCD) for glucose enantiomers, which shows a larger‐than‐one normalized sensitivity compared with metamaterials with chiral response is demonstrated. Furthermore, The potential of SEVCD by detecting a broadband signal using arrayed metamaterials is explored. These findings pave the way toward chiroptical nanophotonic designs for potential biomedical and healthcare applications.

Hybrid‐Phase Assisted Amplitude and Phase Control Using Full‐Space Metasurface

AbstractAchieving independent control of phase and amplitude is pivotal yet challenging for electromagnetic (EM) wave manipulation. Metasurface provides an efficient recipe to this challenge, but most of the work reports so far are still confined in half space (transmission or reflection) and manipulation of linearly polarized EM waves, restricting itself from integrating more functionalities with complex wavefronts into one optoelectronic device. Here, a hybrid phase approach synthesizing propagation and geometric phases is proposed to achieve independent and arbitrary control of amplitude and phase response for circularly polarized (CP) wave in full space by using a non‐interleaved single‐celled metasurface. To validate the concept, a full‐space dual‐channel meta‐hologram is experimentally demonstrated, manifesting images of letters “T” and “R” at lower and upper frequencies (f1 and f2), respectively. The finding of full‐space metasurface opens new possibilities to control CP waves by simultaneous amplitude and phase modulations, which is important for high‐capacity wireless communications, as well as sophisticated functionality, and other advanced meta‐devices.

The Influence of Substrate on the Optical Properties of Gold Nanoslits.

Nanoslits have various applications, including localized surface plasmon resonance (LSPR)-based nanodevices, optical biosensors, superfocusing, high-efficiency refractive index sensors and chip-based protein detection. In this study, the effect of substrates on the optical properties of gold nanoslits placed in free space is discussed; for this purpose, glass BK7 and Al2O3 are used as substrates and the wavelength of incident light is supposed to be 650 nm. The optical properties, power flow and electric field enhancement for gold nanoslits are investigated by using the finite element method (FEM) in COMSOL Multiphysics software. The effect of polarization of an incident electromagnetic wave as it propagates from a gold nanoslit is also analyzed. As special case, the effect of glass and alumina substrate on magnetic field, power flow and electric field enhancement is discussed. The goal of this research is to investigate the phenomenon of power flow and electric field enhancement. The study of power flow in gold nanoslits provides valuable insights into the behavior of light at the nanoscale and offers opportunities for developing novel applications in the field of nanophotonics and plasmonics. The consequences of this study show the significance of gold nanoslits as optical nanosensors.

Electromagnetic interference shielding composites and the foams with gradient structure obtained by selective distribution of MWCNTs into hard domains of thermoplastic polyurethane

In this paper, multilayer thermoplastic polyurethane (TPU)/multiwalled carbon nanotubes (MWCNTs) electromagnetic interference shielding composite foams with gradient structure was prepared. The gradient distribution of effective concentration of filler and cell size were realized by selective distribution of MWCNTs into hard domains of TPU, which improved interlayer interface polarization of electromagnetic waves and impedance matching between the material and the air. The average electromagnetic interference shielding efficiency (EMI SE) of TPU/MWCNTs composites with gradient structure is 1.2 times larger than that of homogeneous composites. After foaming, the average EMI SE of the gradient foams was higher than that of the homogeneous foams, with maximum average EMI SE of 35.4 dB. This work is the first time to correlate the interaction of fillers with the soft domains and hard domains of TPU and EMI shielding performance, providing a feasible method for designing lightweight composites with low filler and better EMI shielding performance.

Special Issue on the Progress and Application of Electromagnetic Materials

Electromagnetic materials refer to materials that can manipulate electromagnetic waves, which can control the amplitude, phase, polarization, spectrum, and other characteristics of electromagnetic waves [...]

Simulation of Spatial Polarization Characteristics of a Triorthogonal Antenna Element for the Tasks of HF Band Bearing

Introduction. Achieving improved accuracy and sensitivity of the direction finding of radio signals represents a relevant research direction in the field of modern HF radio monitoring. HF radio waves propagate through ionospheric layers, which distorts the polarization parameters of the passing electromagnetic wave (EMW). One possible approach to improve the accuracy and sensitivity of the direction finding of HF radio signals consists in the use of an antenna element capable of accepting both components of the electromagnetic field in the antenna array.Aim. A comparative analysis of the proposed triorthogonal antenna element with existing solutions for the tasks of HF band bearing.Materials and methods. Antenna elements and their spatial polarization characteristics were simulated in the MATLAB environment using the Phased Array toolbox.Results. The spatial polarization characteristics of the triorthogonal antenna under study were constructed and compared with an asymmetric vertical vibrator and a biorthogonal antenna. The comparison showed that at small elevation angles, the triorthogonal antenna ensures an energy gain of up to 4.5 dB compared to a biorthogonal antenna and an asymmetric vertical vibrator. At elevation angles of 30…60° and over 60°, the increase in the quality of a signal received by the triorthogonal antenna element reaches 3 dB and 2 dB, respectively.Conclusion. According to the obtained spatial polarization characteristics, the triorthogonal antenna under study can be part of a large-base antenna array of the HF band. The use of this antenna will increase the accuracy and sensitivity of direction finding by means of matching the antenna element with the EMW polarization

Lightweight and flexible Ag-wrapped polyimide aerogel fabrics for electromagnetic interference shielding

Lightweight, flexible and highly effective electromagnetic interference (EMI) shielding fabrics are urgent demanded to protect the human body from harmful electromagnetic radiation. However, the design of fiber microstructures for achieving high-performance EMI shielding still remains significant challenges. Herein, novel EMI shielding fabrics have been designed based on polydopamine-assisted Ag deposition on polyimide (Ag@PI) aerogel fabrics. The Ag@PI aerogel fabric integrates highly conductive Ag and leverages the three-dimensional porous structure of aerogel to facilitate multiple reflections and interface polarization of electromagnetic waves. The Ag@PI aerogel fabrics exhibit ultra-high electromagnetic interference shielding performance of 89.4 dB owing to their unique porous structure, while the Ag@PI fabric without porous structure is only 65.1 dB. The normalized specific shielding effectiveness (SSE) of the Ag@PI aerogel fabrics is up to 812.7 dB cm3 g−1, significantly exceeding that of other EMI shielding textiles reported so far.

All‐Dielectric Multichannel Terahertz Metasurface Empowering Independent Wavefront Manipulation

AbstractMetasurfaces have demonstrated unprecedented capabilities in modulating the polarization and phase of electromagnetic waves and formed an emerging field of research, driving the exploitation of versatile compact devices. In this work, one transmission‐mode, multichannel all‐silicon metasurface platform that can implement functionalities separately in two orthogonally polarized output fields under linearly polarized incidences is proposed, which can effectively promote the design flexibility. Specifically, a single metasurface can realize multiple independent target phase distributions carrying specific phase relationships, thus enabling different information processing in different linear polarization states. For proof‐of‐principle experimental exhibitions, a monolayer metasurface composed of silicon pillars is designed, fabricated, and characterized to demonstrate the ability of multi‐dimensional light field control, such as polarization‐switchable focusing beam. Moreover, the other designed metasurface can generate polarization‐switchable Bessel vortex beams under linearly polarized incidences, which also verifies the flexibility and practicality of such platform. This metasurface platform may lead to new optical components, involving multichannel singular beam generators, information encoders, and holographic encryption devices.

Villari effect in FeSe1–xSx

Acoustoelectric transformation (occurrence of electromagnetic radiation under the action of an elastic wave) in a FeSe0.925S0.075 crystal in the presence of an external magnetic field has been studied. It is shown that the application of the magnetic field along the direction of propagation of the elastic wave leads to a rotation of the plane of polarization of the emitted electromagnetic wave. The physical mechanism is that the elastic deformation leads to the appearance of a non-diagonal component of the magnetic susceptibility and to the generation of an additional alternating magnetic moment perpendicular to the external magnetic field and to the elastic displacement. The observed features are interpreted as a manifestation of the Villari effect. A phenomenological description of the experimental results is presented. The observed effect shows that the symmetry of the low-temperature FeSe1–xSx phase belongs to the triclinic syngony.

RCS reduction effect based on transparent and flexible polarization conversion metasurface arrays

In recent years, radar cross section (RCS) reduction techniques based on electromagnetic absorption materials have become a hot research topic in the field of electromagnetic stealth. This paper proposes a transparent conformal encoded metasurface based on polarization rotation units. The metasurface array is optimized using the whale optimization algorithm to construct a 1-bit polarization rotation encoded unit array. The proposed metasurface array exhibits good RCS reduction and electromagnetic wave polarization conversion performance in the frequency range of 13.2–20.7 GHz. The RCS reduction effect of the metasurface array is effective at different angles and polarization states. The metasurface is composed of transparent and flexible materials, namely ITO, PET, and PVC plastic. It exhibits conformal properties while maintaining a high physical transmittance of up to 83.6%. The RCS reduction performance of the metasurface is studied under different curvatures and demonstrates good conformal scattering characteristics. The RCS variation of ITO material compared to traditional metallic materials was also analyzed. It was found that ITO with low surface resistance is an effective means to broaden the RCS bandwidth. This makes it suitable for theoretical research and the design of electromagnetic stealth for electronic devices such as radars and antennas with different curvatures.

Frequency and Angle Multiplexed Metadevices with Multifunctional Polarization Modulation

AbstractMultifunctional polarization controllers are highly desirable in numerous fields due to their potential applications. Although the emergence of metasurfaces provides a powerful platform for manipulating the polarization of electromagnetic waves, metasurfaces have not yet enabled multifunctional controllers. Here, this work demonstrates an effective strategy to design a multifunctional polarization controller through the integration of frequency and angular multiplexing. As an experimental proof, a non‐planar dual‐multiplexed metadevice composed of a chiral metagrating array and an anisotropic metasurface is fabricated by printed circuit board technology. The experiments show that at least five distinct functions, including ultra‐broadband linear‐to‐circular polarization conversion in 2.5–6.3 GHz, ultra‐broadband linear‐to‐linear polarization conversion in 6.6–11.0 GHz, strong optical activity between 11.4 and 12.2 GHz, giant linear and circular dichroism ≈5.96 and 12.97 GHz, respectively, can be accomplished by the proposed meta‐multiplexer. Hence, the proposed metadevice can act as high‐efficiency bifunctional waveplate, polarization rotator, linear polarizer, chiral metamirror, and so on, enabling more application flexibility. The concept of integrating multidimensional multiplexing proposed here will be of great benefit to the design of novel multifunctional polarization controllers.

Graphene-based metasurface for real-time control of three electromagnetic wave modes and polarization state

In various practical applications, the demand for switchable metasurfaces with versatile functionalities has grown significantly. This paper proposes a graphene-based metasurface that offers independent control over all three electromagnetic (EM) wave modes (i.e., reflection, transmission, and absorption) as well as the polarization state for both reflection and transmission modes, all achieved in real-time at terahertz frequency. The metasurface is designed with a multilayer structure, comprising quartz, gold, and graphene. Two graphene sheets are placed at the beginning and end of the structure to control specific functionalities. By dynamically adjusting the chemical potential of each graphene sheet, the proposed metasurface can manipulate all three EM wave modes and convert linear to circular polarization independently for both reflection and transmission modes. Additionally, the metasurface can switch from polarization conversion to without polarization conversion of the reflected wave by adjusting the chemical potential of graphene. Due to its numerous switchable functions and a high degree of freedom, the presented metasurface has the potential to be used in wireless communication, biomedicine, and optoelectronic devices.

A transparent zinc oxide based metamaterial for perfect absorption of long- wavelength and mid-wavelength infrared spectral bands

A high absorption capabilities in atmospheric transparency windows lies at mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) region is important for various applications, particularly, for passive thermal cooling and camouflage technology compatible with infrared (IR) lasers. In this paper, we proposed a simple and cost-effective design for a tri-layered metamaterial based on zinc oxide (ZnO) which exhibits almost perfect absorption in both the mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) regions with excellent transmission in the visible range. It consists of a metal-dielectric-metal sandwiched structure with a two-dimensional periodic pattern of gallium doped ZnO circular discs at the top, ZnO in the middle, and an aluminum doped ZnO at the bottom. The proposed metamaterial exhibits almost perfect absorption in both the LWIR (∼ 10 µm) and MWIR (∼ 5 µm) regions, while maintaining excellent transmission (∼ 75%) in the visible region. Further, it also exhibits a better angular (0–50°) insensitivity with respect to the incident angle and to the polarization (TE and TM) of electromagnetic wave. The proposed metamaterial has potential applications in thermal cooling/emission and infrared camouflage technology.