Electromagnetic Polarization Research Articles

Ground Electromagnetic and Electric Studies for Um Salim Gold Mine, Central Eastern Desert, Egypt

Horizontal Loop Electromagnetic (HLEM) and Induced Polarization (IP) methods have been carried out within Um Salim gold mine area. The study area reveals special importance, as it comprises rock units, which show some indication of the presence of various mineralization. The result of HLEM has shown significant and well-defined conductive zones are recorded along with the four used frequencies (110 Hz, 440 Hz, 1760 Hz, and 7040 Hz) at the station 2,782,900 and station 2,782,880 of two (HLEM) profiles (596,050 N & 596,240 N) respectively, that may reflect the sources of the conductive bodies are situated at shallow depths continued to considerable depths. The result of IP exhibits a strong anomalous zone centered at stations 140 and 240, with chargeability values ranging (37 to more than 120 mV/V) on chargeability model section, and corresponding to high resistivity on resistivity model section which may reflect considerable surface and subsurface disseminated mineralization. Through the integration between HLEM and IP a core drilling is recommended at station 140 on IP profile which coincides with station 2,782,850 on HLEM profile (596,240 N) to a depth of concerning 100m take a look at the thickness, depth, and grade of mineralization.

Unitary quantum lattice simulations for Maxwell equations in vacuum and in dielectric media

Utilizing the similarity between the spinor representation of the Dirac and the Maxwell equations that has been recognized since the early days of relativistic quantum mechanics, a quantum lattice algorithm (QLA) representation of unitary collision-stream operators of Maxwell's equations is derived for both homogeneous and inhomogeneous media. A second-order accurate 4-spinor scheme is developed and tested successfully for two-dimensional (2-D) propagation of a Gaussian pulse in a uniform medium whereas for normal (1-D) incidence of an electromagnetic Gaussian wave packet onto a dielectric interface requires 8-component spinors because of the coupling between the two electromagnetic polarizations. In particular, the well-known phase change, field amplitudes and profile widths are recovered by the QLA asymptotic profiles without the imposition of electromagnetic boundary conditions at the interface. The QLA simulations yield the time-dependent electromagnetic fields as the wave packet enters and straddles the dielectric boundary. QLA involves unitary interleaved non-commuting collision and streaming operators that can be coded onto a quantum computer: the non-commutation being the very reason why one perturbatively recovers the Maxwell equations.

Research on RCS Simulation Characteristics of Fixed Low-Grazing-Angle FOD Radar

Fixed low-grazing-angel foreign object debris (FOD) radar, which is erected at a designated height beside the airport and scans the runway at a low-grazing angle, is used to detect foreign object debris on airport runways. In operation, it is found that the power of reflected electromagnetic wave decreases significantly when the radar is erected at some height, as a result of which the radar detection rate reduces. In this paper, the electromagnetic reflection and polarization modes of fixed low-grazing-angle radar are analyzed based on some concepts of refraction characteristics of electromagnetic wave, such as Fresnel’s Law and Brewster’s Angle. Then the paper explains the theoretical reasons for this problem. Meanwhile, the GO & MLFMM algorithm is used to simulate the relationship between radar height and radar reflected power, and finally the theoretical results are verified.

Electromagnetic Emission Driven by Electron Beam Instability in the Jovian Polar Regions

Abstract Upward energetic electron beams are often observed simultaneously with the plasma-wave emission in the Jovian polar regions, where the electron cyclotron frequency Ωce is much larger than the plasma frequency ω pe. This study gives a comprehensive wave and instability analysis in the extreme plasma environment with Ωce ≫ ω pe. We find that energetic electron beams can effectively drive the electron acoustic/magnetoacoustic instability. The excited electron acoustic/magnetoacoustic waves distribute from the parallel direction to the highly oblique direction, and their wave frequencies are always below the plasma frequency. These waves are electrostatic at parallel propagation, and exhibit electromagnetic polarization at oblique propagation. These theoretical predictions are qualitatively consistent with the main observed features of electromagnetic fluctuations in the Jovian polar regions. Therefore, we propose that upward electron beam-driven electron acoustic/magnetoacoustic waves can contribute to the plasma-wave emission in Jupiter’s polar environments. Furthermore, energetic electron beam-driven electron acoustic/magnetoacoustic waves may exist in Saturn’s polar regions and solar flare loops, where the extreme plasma condition Ωce ≫ ω pe is satisfied in these plasma environments.

Metasurfaces as Artificial Crystals for Electromagnetic Polarization Handling

Metasurfaces acting on electromagnetic fields have emerged as powerful tools that can address all the wave’s degrees of freedom: amplitude, phase and polarization. It is especially with respect to polarization that their role is steadily growing: metasurfaces can indeed perform, by design, operations that would usually require very specific, delicate and expensive natural or synthetic ordinary crystals. Here, I will first briefly review the history of light polarization, and its connection with ordinary crystals. Subsequently, I will highlight in which sense metasurfaces are artificial quasi-two-dimensional crystals, evidencing their potential as future polarization-handling (meta) materials.

Polarization Control with Helical Metasurfaces

The ability to fully control the polarization of light using chiral metadevices has drawn considerable attention in various applications of integrated photonics, communication systems, and life sciences. In this work, we propose a comprehensive approach for the design of metasurfaces with desired polarization properties for reflected and transmitted waves based on the proper spatial arrangement of chiral inclusions in the unit cell. Polarization conversion is achieved by engineering induced electric and magnetic dipole moments of the metasurface inclusions. We show that under a proper arrangement, the same inclusion can be used as a building block of metasurfaces with drastically different wave-transformation functionalities. The horizontally and vertically oriented metallic helices were used as simplest chiral inclusions, which can be manufactured by the established 3D fabrication techniques from THz up to the visible spectral range. The proposed metadevices provide a deep understanding of the light–matter interaction for polarization conversions with helix-based structures and opens the way to new possibilities of electromagnetic polarization control with advanced chiral metadevices in communication and imaging systems.

Ultrathin tri-band reflective cross-polarization artificial electromagnetic metasurface

A high-efficiency tri-band artificial electromagnetic (EM) polarization manipulating metasurface is proposed, which is employing two metal rectangle rings composed of a single-layer reflectance surface. There are three frequency bands generated by the artificial EM polarization manipulating metasurfaces, with 3-dB bandwidth at 9.10–12.40, 15.55–23.80 and 24.71–30.00 GHz, and the relative bandwidth is 30.7%, 41.9% and 19.4%, respectively. The polarization converter ratio of the polarization manipulating metasurfaces is great than 90% at 9.8–12.2, 19–22.6, and 24.9–29.5 GHz, respectively. There are five resonance frequencies at 10.5, 11.8, 20.9, 25.7 and 28.3 GHz, where the polarization converter ratio is almost reached 100%. Equivalent circuit and surface current distributions reveal that the coupling results from the strong electric and magnetic resonances between the top surface and bottom ground. Experimental results of the prototype are basically consistent with the simulation results, which clearly show that the metasurfaces have multiband characteristics and higher efficiency.

Mid-infrared tunable triple-band cross-polarization converter based on a periodic ellipse graphene patch with a slit

A novel triple-band, tunable, high-efficiency, mid-infrared reflected cross-polarization converter based on a graphene metasurface is proposed and studied, which comprised a periodic ellipse graphene patch with a slit, a dielectric spacer, and a metal gold substrate. Numerical simulations indicate that the proposed converter can convert a linearly polarized wave to its cross-polarized wave at three resonance frequencies due to the superimposition of the two reflected components with a near 180° or 0° phase difference. The polarization conversion ratios of the three bands are 98.29%, 98.42%, and 97.64%, respectively. The polarization converter can be dynamically tuned by changing the Fermi energy. Our proposed tunable polarization converter has great potential in the application of electromagnetic polarization control.

Photoalignment and photopatterning: New liquid crystal technology for displays and photonics

Objectives. Since the end of the 20th century, liquid crystals have taken a leading position as a working material for the display industry. In particular, this is due to the advances in the control of surface orientation in thin layers of liquid crystals, which is necessary for setting the initial orientation of the layer structure in the absence of an electric field. The operation of most liquid crystal displays is based on electro-optical effects, arising from the changes in the initial orientation of the layers when the electric field is turned on, and the relaxation of the orientation structure under the action of surfaces after the electric field is turned off. In this regard, the high quality of surface orientation directly affects the technical characteristics of liquid crystal displays. The traditional technology of rubbing substrates, currently used in the display industry, has several disadvantages associated with the formation of a static charge on the substrates and surface contamination with microparticles. This review discusses an alternative photoalignment technology for liquid crystals on the surface, using materials sensitive to polarization of electromagnetic irradiation. Also, this review describes various applications of photosensitive azo dyes as photo-oriented materials. Results. The alternative photoalignment technology, which employs materials sensitive to electromagnetic polarization, allows to create the orientation of liquid crystals on the surface without mechanical impact and to control the surface anchoring force of a liquid crystal. This provides the benefits of using the photoalignment technology in the display industry and photonics—where the use of the rubbing technology is extremely difficult. The optical image rewriting mechanism is discussed, using electronic paper with photo-inert and photoaligned surfaces as an example. Further, different ways of using the photoalignment technology in liquid crystal photonics devices that control light beams are described. In particular, we consider switches, controllers and polarization rotators, optical attenuators, switchable diffraction gratings, polarization image analyzers, liquid crystal lenses, and ferroelectric liquid crystal displays with increased operation speed. Conclusions. The liquid crystal photoalignment and photopatterning technology is a promising tool for new display and photonics applications. It can be used for light polarization rotation; voltage controllable diffraction; fast switching of the liquid crystal refractive index; alignment of liquid crystals in super-thin photonic holes, curved and 3D surfaces; and many more applications.

A 2 b Dual-Band Multifunction Frequency Selective Surface

A novel 2 b dual-band multifunction active frequency selective surface is proposed. The frequency response of the surface is guided by four binary states controlled via direct current supply biasing of two p-i-n diodes. The binary combination states 00 and 11 offer transmission at center frequencies of 2.3 and 5 GHz and shield to bands at 5 and 2.3 GHz for transverse electric/transverse magnetic modes, respectively. The related fractional bandwidths of the lower and upper frequency bands are $127\%$ and $75\%$ with insertion losses of 0.5 and 0.2 dB, respectively. The binary state 10 offers transmission at 2.3 GHz frequency and shields to the passbands at 5 GHz frequency when the incident-plane wave is transverse electric (TE)-polarized. The binary state 01 allows transmission at 5 GHz frequency and shields to the passband at 2.3 GHz frequency when the incident plane wave is transverse magnetic (TM)-polarized. The design of the structure is flexible to electromagnetic switching and polarization selection for the two bands with the advantage of low insertion loss in the passbands. The prototype of the structure is fabricated and measured, transmission response at all binary states concurs well with the full-wave simulated transmission response.

Design of molybdenum disulfide@polypyrrole compsite decorated with Fe3O4 and superior electromagnetic wave absorption performance

The MoS2@polypyrrole@Fe3O4 composite was skillfully synthesized via a novel one pot method. No any separation step during the synthesis process, and the Fe2+ was successively utilized to prepare the Ppy and Fe3O4, which can achieve a high utilization of raw materials. The characterization about microstructure, crystal form, elemental composition and surface functional groups verify the structure of MoS2@polypyrrole@Fe3O4. Its hysteresis loop indicates that the composite performs typical soft magnetism behavior, with a magnetic saturation value of 20.3 emu.g−1, which is helpful to improve the magnetic loss for EM wave absorbing. The reflection loss curve suggested that the composite exhibits superior EM wave absorption performance, with a minimum reflection loss value of –32 dB at the specimen thickness of just 2.0 mm due to the fair electromagnetic matching, interface polarization and interface relaxation. In addition, the one pot method used in this work can promisingly be applied to prepare other similar composites such as carbon fiber@polypyrrole@Fe3O4, graphene@polypyrrole@Fe3O4.

Two Dimensional Full‐Wave Modeling of Propagation of Low‐Altitude Hiss in the Ionosphere

AbstractWe investigate the propagation characteristics of low‐altitude hiss in the ionosphere by numerical simulation with a two‐dimensional full‐wave model. The simulation results demonstrate that linear mode conversion from whistler to H+ band electromagnetic ion cyclotron wave and polarization reversal occur simultaneously where wave frequency matches the H+−He+ crossover frequency. This mode conversion efficiency shows sensitive dependence on wave normal angle and plays a significant role in the propagation of whistler emission near the local proton gyro‐frequency in the ionosphere by redistributing the wave energy below and above the H+−He+ cutoff frequency, which can explain the low‐altitude hiss observed by the Freja and Detection of Electromagnetic Emissions Transmitted from Earthquake Regions satellites, respectively. The energy of whistler‐mode low‐altitude hiss emission can be transferred to reflected left‐hand polarized electromagnetic ion cyclotron through mode conversion and the efficiency reaches a maximum for intermediate incident wave normal angle (of 45°).

High-efficiency non-diffractive generator of arbitrary vectorial optical fields with minimal optical elements

Tailoring electromagnetic waves has a wide range of applications, such as optical trapping, focus engineering, imaging, laser cutting, and optical communication. To do so, the spatial distribution of at least one of the four degrees of freedom of electromagnetic waves, amplitude, phase, polarization ratio, and retardance, must be modified. Arbitrary vectorial optical fields (VOF) can be engineered by spatially modulating all four degrees of freedom simultaneously. However, existing dynamic vectorial optical field generators (VOF-Gens) require intensive alignment and many optical elements in order to achieve high efficiency. Here, we design a dynamic VOF-Gen that can generate arbitrary VOFs using only five optical elements. Experimentally, we demonstrated an efficiency of 72%, the highest ever demonstrated.

Impact of Field Polarization on Radiated Emission Characterization in an Open TEM Cell

This article presents a comprehensive study of the influence of electromagnetic (EM) field polarization on radiated emission characterization in an open transverse EM (TEM) cell, which is usually neither considered in the measurement process nor clearly identified. It also takes into account the influence of the operating frequency with respect to the higher order mode cutoff frequency of the cell, the latter being generally unknown to the experimenter. Commonly used 433-MHz (LoRa) and 2.4-GHz (Wi-Fi) antennas were placed inside an open TEM cell in different orientations in order to investigate the impact of the antenna polarization. For antennas parallel to the septum, a 1.6–8.6-dB difference in power levels collected by the cell (corresponding to a 31%–86% underestimation), for different polarizations, depending on the operating frequency being below or above the higher order mode cutoff frequency, was obtained between orthogonal orientations due to reduction in $E$ - and (mainly) $H$ -field levels, leading to significant uncertainty on power levels. For the 2.4-GHz antenna perpendicular to the septum, the power level was highly dependent on both the antenna orientation and location along the cell’s axes, being more dependent along the main axis. This clearly demonstrates that the physical phenomena due to the polarization of the radiating element and the cell’s dominant mode frequency must be characterized and estimated, in addition to the generally known tangential $H$ -field coupling to integrated circuit pins or printed circuit board (PCB) traces. This leads to an update of best practices of IEC 61000-4-20 or IEC 61967-2 emission testing.

Development of a novel approach for recovering SIP effects from 1-D inversion of HEM data: Case study from the Alut area, northwest of Iran

We have developed a novel approach for recovering the induced polarization (IP) effects from one-dimensional (1-D) inversion of helicopter-borne electromagnetic data (HEM). To achieve this aim, we incorporate both electromagnetic and spectral induced polarization effects within the HEM data by taking the frequency dependence behaviour of resistivity/conductivity of polarizable formation into account. Furthermore, we have included the EM sensor altitude, magnetic permeability and dielectric permittivity of subsurface layers in order to conduct the full solution of forward operator. In this regard, we have calculated the magnetic permeability from the inversion of aeromagnetic data and incorporated the sensor altitude and dielectric permittivity as additional model parameters to be recovered using the inversion of the HEM data. We have carried out both forward and inverse modelling of the HEM data by implementing fast Hankel transform and hybrid algorithm including very fast simulated annealing (VFSA) and Marquardt-Levenberg (ML) strategies, respectively. This approach enables us to recover model parameters comprising of relaxation parameters of Cole-Cole model, dielectric permittivity and thickness of layered half space model and sensor altitude above the earth surface using 1-D inverse modelling of HEM data.We have tested our approach on both synthetic and field DIGHEM data. Implementing the forward solution indicates that incorporation of the IP effects may shift the frequency domain electromagnetic (FDEM) response so that it yields the sign reversal signature in the in-phase component at low frequencies. Moreover, the results of the inverse modelling of the HEM data show that the IP effect could be recovered using our approach effectively. It provides fast and cost-effective quantitative tool for recovering the IP effect from HEM data for the sake of more precise characterization of buried polarizable formations in the wide area. In addition, incorporation the IP effect along with magnetic permeability and sensor altitude provides a significant degree of improvement in the inversion and interpretation of negative responses occurred in the in-phase component at low frequencies.

New Agile Matrix Antenna for Nano-satellite Telemetry Using Bimodal Pattern Reconfiguration

This review deals with the design of a new reconfigurable beam antenna used to improve the efficiency of spatial telemetry links on Nano-Satellite. Advances in this domain show the needs to serve some applications with special electromagnetic beams and polarization patterns especially from LEO and MEO Space-Earth links. The RF front end must be capable to switch from high gain directive pattern to special pattern called Isoflux where the gain must be concentrated at high elevation angles with another challenge also the circular polarization. The content is a part of the CNES project that serves for multimode beam forming applications. This agile beam antenna is not built on the well-known array concept: AESA stands for Agile Electronically Scanned Array but using a new approach called ARMA standing for Agile Radiating Matrix Antenna. Contributions will show the small size elementary antenna of ARMA called Pixel, the polarization circuits that fit the challenges of the Nano-Satellite dimensions, the enhancement in the circular polarization requirements and theoretical and experimental comparison. Special beam forming required in the telemetry applications are achieved with better gain especially for the aim of wide beams. The use of the new approach will show the beam forming advantage of radiating the energy to high elevation angles.

Analytical Inverse Design of Polarization-Insensitive Photonic Filters by Tailoring Fabry-Perot Interference

Filtering of photonic signals of a certain frequency while suppressing all the others of a specific band for both electromagnetic signal polarizations, becomes possible with a single dielectric layer by properly engineering the occurred Fabry-Perot interference. Analytical formulas for combinations of cavity size, material texture and incoming angle are given so that the filtering purpose is optimally served. In this way, inverse design for a simple class of optical setups is rigorously performed and, if the employed medium is very dense and the working band narrow enough, sharp filters with increased frequency selectivity are obtained.

Ultra high-speed all-optical coherent memory cell

We study the interaction of two counterpropagating unipolar video pulses of electromagnetic radiation in a dense resonant two-level medium. The pulse durations are less than one oscillation period of an atomic transition. We show that a polariton cluster (i.e. the compact long-living strongly coupled state of electromagnetic field and matter polarization) is created, when two unipolar pulses collide in a resonant medium of the frequency ω0 (the pulses correspond to self-induced transparency solitons of the same amplitudes and opposite polarities).We have studied for the first time the conditions of maximal excitation of a resonant polarization in the polariton cluster volume. We show that there exist optimal durations and amplitudes of the recording pulses. We studied the processes of double and multiple recording and erasing of an optical memory cell in a thin layer of a resonant medium (quantum dots). We demonstrated that the pulse rate of the recording-erasing pulses can reach 60 000 GHz and higher, which happens under the coherent regime of the interaction between the electromagnetic field and polarization of the medium.

High-Efficiency Dual-Frequency Reflective Linear Polarization Converter Based on Metasurface for Microwave Bands

A dual-broadband and high-efficiency reflective linear polarization converter based on an anisotropic metasurface is presented. The device consists of two symmetrical, double-slotted metallic split-rings and one criss-cross structure, a dielectric layer, and a completely reflective metallic ground. The converter exhibits four resonances and can near-perfectly convert x- or y-polarized incident waves into cross-polarized waves in the frequency ranges of 9.38–13.36 GHz and 14.84–20.36 GHz. The polarization conversion ratios (PCRs) of the two bands are 98.21% and 99.32%, respectively. The energy conversion ratio (ECR) for energy loss measurement is almost 100% in these frequency bands. The polarization conversion principle is studied. The bandwidths and PCRs of the two bands are determined by varying the dielectric layer thickness. The simulation results are consistent with experimental observations. The designed dual-broadband and high-efficiency metasurface has great potential in the application of electromagnetic polarization control.

Electromagnetic polarization conversion based on Huygens' metasurfaces with coupled electric and magnetic resonances.

Electromagnetic (EM) polarization control is a key issue in various studies on communication and imaging systems. Two-dimensional metasurfaces have been employed to realize polarization conversion based on chiral, anisotropic structures. Herein, we employ Huygens' metasurfaces that utilize both electric and magnetic resonances when interacting with EM waves to realize polarization manipulation. Polarization conversion is achieved by introducing direct coupling between the equivalent electric and magnetic sources. A polarization conversion splitter as well as reflective and transmissive polarization convertors are designed and verified by simulations and experiments. The proposed polarization manipulation devices possess compact dimensions in the deep sub-wavelength regime and maintain good angular performance for oblique incidences up to 60°.