Wide-angle Polarization Research Articles

Wide angle wide band polarization insensitive metamaterial absorber for C, X and Ku band application with hexagonal packaging

Abstract In this paper wide angle wide band polarization insensitive Metamaterial absorber (MA) has been proposed. The proposed unit cell structure consists of hexagonal concentric ring along with hexagonal packing. The structure is fabricated on FR4 substrate. The advantage of hexagonal packing is that it covers less area as compared to square packing. The unit cell structure is scaled w.r.t hexagonal ring and resistance of the substrate. The absorptivity achieved range from 6.54 to 14.85 GHz having Bandwidth (BW) of 8.31 GHz. The metamaterial behaviour of the structure is proven by plotting real and imaginary pat of permittivity and permeability. Absorption mechanism is shown by plotting surface current distribution at the top and bottom of the surface. The proposed MA structure is analysed for normal and oblique incidence. From the normal incidence it was found that structure has wide angle polarization insensitive. The absorptivity of the fabricated structure is measured inside the anechoic chamber. The simulated and measured plot is compared and found that both the results are very close to each other. At last, the proposed and already reported MAs are compared and from the observation it was found that proposed unit cell have larger BW compact in size, polarization insensitive and have hexagonal packing. The proposed MA covers partial C band, full X band and partial Ku band. The Proposed MA found practical applications for satellite communication, Wi-Fi devices, cordless telephone, military, air traffic control, defence tracking, vehicle speed detection.

Symmetric engineered central cross-shaped broadband metamaterial absorber with high absorption and stability for solar sailing and solar energy applications

We propose a theoretical design and analysis of a broadband metamaterial absorber (MMA) with significant potential for solar sailing applications which is a method of spacecraft propulsion that usages the momentum of sunlight to propel a spacecraft through space. The absorber features a metal-dielectric-metal configuration with a tungsten (W) based resonator and ground plane, and a Silicon-dioxide (SiO₂) substrate. Addressing the critical need for materials that can efficiently harness solar radiation for propulsion in space, our design achieves an average absorption of 99.15 % over a broad spectrum from 250 nm to 1200 nm, covering the UV–Visible–NIR regions, with near-unity absorption peaks at 362 nm and 915.8 nm. It maintains high absorptions of 84.9 % and 86 % under transvers electric and transvers magnetic modes respectively, demonstrating excellent wide incident angle stability and polarization insensitivity due to its symmetric design. PCR values close to zero confirm its functionality as an absorber rather than a polarizer. The MMA shows minimal deformation across temperatures from 500 K to 1750 K and remains stable under various mechanical stresses, proving its durability and efficiency in space. Additionally, in solar thermophotovoltaic (STPV) systems, the MMA demonstrates high photothermal conversion efficiency (PTCE) over a wide temperature range (500 °C to 1500 °C) and different concentration factors. This dual functionality highlights its potential for both efficient space exploration and terrestrial solar energy harvesting, making it a versatile tool for future technological applications.

Transparent ultrawideband polarization-insensitive absorber with optimal thickness based on a grid ITO structure

With the large-scale commercialization of broadband wireless communication technologies, interference between spatial electromagnetic waves (EMWs) is becoming increasingly serious. As devices for solving electromagnetic interference (EMI) problems, microwave absorbers (MAs) have become increasingly mature with the rapid development of artificial electromagnetic structures. However, current MAs still face challenges in terms of wideband absorption, wide-angle absorption, thickness, etc., which limits their application scenarios. Therefore, this paper proposes a transparent ultrawideband polarization-insensitive absorber based on a grid indium tin oxide (ITO) structure. This design adopts a multilayer structure with a total thickness of 3.525 mm (0.114λ L ), close to the predicted minimum thickness, to expand the bandwidth. The grid-patterned ITO film resonant structure and ITO film ground plane are designed to further improve optical transmittance by increasing duty ratios. Simulation results demonstrate over 90% absorption from 9.7 GHz to 69.2 GHz, with a fractional bandwidth (FBW) of 150.8%. The absorber has good incident angle stability and polarization insensitivity. When the incident angle varies within 0-60°, the proposed absorber maintains an absorption close to 80% over an ultrawideband range, and the absorption remains nearly constant when the polarization angle changes from 0° to 90°. The fabricated sample shows a visible light transmittance of approximately 73.2%, and shows an absorption performance consistent with simulations in the 6-38 GHz frequency range, validating the effectiveness of the proposed design. Due to its transparent, ultrawideband absorption, wide incident angle stability and polarization insensitivity properties, this proposed absorber has important guiding significance for applications in high-frequency transparent electronics, radars, communications systems and other devices working in the microwave frequency band.

High efficiency and broadband wide-angle linear polarization converter based on dumbbell-like resonant structure

In this paper, a broadband wide-angle reflective linear polarization converter is designed, of which a dumbbell-like resonant structure is applied to form the unit cell of the periodic metasurface. Research results show that characteristics of broadband polarization conversion with higher polarization conversion ratio (PCR) in the range of 13.3 GHz to 24.1 GHz come from the multiple electric and magnetic resonances along the dumbbell-like resonant unit. Meanwhile, the entire conversion performance can be well controlled through changing the structural parameters. In addition, the property of wide-angle polarization conversion can make it convenient for the real application. Due to the simple structure together with the excellent performance of the proposed linear polarization converter, it has promising values in polarization converting, detecting, imaging and so on in the GHz frequency range.

Double elliptical resonator based quadruple band metamaterial absorber for EMI shielding applications in microwave regime

A quadruple band wide angle polarization insensitivity metamaterial absorber based on double elliptical resonator structure for electromagnetic interference (EMI) shielding applications in microwave regime has been considered in this paper. The proposed metamaterial absorber (MA) unit cell comprises of a top metallic resonating patch and a ground copper, both of which are separated by an inexpensive FR-4 substrate with a thickness of 0.0185λ and an electrical size of 0.138λ, at lowest resonance frequency. The proposed MA demonstrates the peak absorption of 97 %, 99.9 %, 99.9 % and 99.6 % at 3.46 GHz, 6.44 GHz, 7.89 GHz and 12.44 GHz, respectively for transverse-electric (TE) mode at normal incidence. The quadruple band absorption mechanism has been understood by the analysis of electromagnetic field with surface current distribution. In addition, the designed MA also exhibits near unity absorption for a polarization and oblique incident angle up to 60° for TE mode. The proposed MA offers greater than 35 dB shielding effectiveness in all bands under both simulated and measured environment. The designed MA has been fabricated and measured to validate the simulation results. The agreement between the measured and simulated results allow for EMI shielding applications in microwave regime.

Omnidirectional defect mode in one-dimensional photonic crystal with a (chiral) hyperbolic metamaterial defect.

The wavelength of defect mode in all-dielectric photonic crystals (PCs) with a dielectric defect are blue-shifted as incident angle increases for both transverse electric and transverse magnetic (TM) polarized waves. The blue-shifted property of defect mode limits the design of some optical devices including omnidirectional optical filters and wide-angle polarization selectors. Here we introduce a hyperbolic metamaterial (HMM) layer as a defect into dielectric one-dimensional photonic crystals (1DPCs) to obtain an omnidirectional defect mode for TM polarized waves at near-infrared regimes. Since only one HMM layer is introduced, omnidirectional defect mode with transmittance as high as 71% can be realized. Because of the unusual angle-dependence of propagating phase in the HMM defect, the total phase for satisfying the resonance condition of defect mode can be unchanged in a wide-angle range at a fixed wavelength, which leads to the omnidirectional defect mode. Moreover, the manipulation of propagating phase can be generalized to the case of circularly polarized waves, and we obtain an omnidirectional defect mode for left-handed circularly polarized waves in 1DPCs with a chiral hyperbolic metamaterial defect. Nevertheless, the defect mode for right-handed circularly polarized waves is still blue-shifted. Such spin-selective omnidirectional defect mode can be utilized to greatly enhance circular dichroism in a wide-angle range up to 64.1°. Our structure facilitates the design of omnidirectional optical filters with a high transmittance and circular polarization selectors working in a wide-angle range.

A redshifted photonic bandgap and wide-angle polarization selection in an all-hyperbolic-metamaterial one-dimensional photonic crystal.

According to the Bragg scattering theory, photonic bandgaps (PBGs) in all-dielectric one-dimensional (1-D) photonic crystals (PhCs) are polarization-insensitive. This polarization-insensitive property of PBGs poses a challenge in wide-angle high-performance polarization selection. Herein, we theoretically investigate the angle dependence of the PBGs in a novel kind of 1-D PhC called all-hyperbolic-metamaterial (all-HMM) 1-D PhC entirely composed of HMMs. As the incident angle increases, the PBGs in all-HMM 1-D PhCs exhibit the redshift property under transverse magnetic polarization while exhibiting the blueshift property under transverse electric polarization. Empowered by the polarization-sensitive property of the PBGs, wide-angle high-performance polarization selection can be theoretically achieved. Such a wide-angle polarizer would be useful in liquid crystal displays, quantum interferometers, and Q-switched lasers.

A wide angle polarization insensitive multi-band metamaterial absorber for L, C, S and X band applications

A wide angle polarization insensitive multi-band metamaterial absorber for L, C, S and X band applications

Polarization Agile Beam Steering by Subarray Antenna Module Design to Compensate Wide-Angle Polarization Discrepancy of User Equipment Antenna Radiations at mmW Frequencies

An antenna-in-module (AiM) architecture at millimeter-wave frequencies for a base transceiver system (BTS) is developed for electromagnetic (EM) radiation with an agile polarization tunable capability. This may reduce the polarization mismatch to a user equipment (UE) antenna, where the mismatch becomes severe in wide-angle scans. The AiM first implements a dual-polarization feature on its antenna elements and then integrates active radio frequency (RF) phase shifters and power amplifiers/attenuators to provide dynamically adjustable weightings. Considering the received fields of a UE antenna, the weightings of the AiM antennas are appropriately tuned to obtain the maximum signal strength from the UE antenna. In this article, the theoretical concept and the antenna architecture are presented. Full-wave simulations using HFSS and the measurement results of the AiM prototype are presented to validate its feasibility.

Wide angle insensitive and polarization independent graphite based superwideband absorber

Wide angle insensitive and polarization independent graphite based superwideband absorber

Photonic Bandgaps of One-Dimensional Photonic Crystals Containing Anisotropic Chiral Metamaterials

Conventional photonic bandgaps (PBGs) for linear polarization waves strongly depend on the incident angle. Usually, PBGs will shift toward short wavelengths (i.e., blue-shifted gaps) as the incident angle increases, which limits their applications. In some practices, the manipulation of PBGs for circular polarization waves is also important. Here, the manipulation of PBGs for circular polarization waves is theoretically investigated. We propose one-dimensional photonic crystals (1DPCs) containing anisotropic chiral metamaterials which exhibit hyperbolic dispersion for left circular polarization (LCP) wave and elliptical dispersion for right circular polarization (RCP) wave. Based on the phase variation compensation effect between anisotropic chiral metamaterials and dielectrics, we can design arbitrary PBGs including zero-shifted and red-shifted PBGs for LCP wave. However, the PBGs remain blue-shifted for RCP wave. Therefore, we can design a high-efficiency wide-angle polarization selector based on the chiral PBGs. Our work extends the manipulation of PBGs for circular polarization waves, which has a broad range of potential applications, including omnidirectional reflection, splitting wave and enhancing photonic spin Hall effect.

VERDI: VERsatile DIffractometer with wide-angle polarization analysis for magnetic structure studies in powders and single crystals.

The VERsatile DIffractometer will set a new standard for a world-class magnetic diffractometer with versatility for both powder and single crystal samples and capability for wide-angle polarization analysis. The instrument will utilize a large single-frame bandwidth and will offer high-resolution at low momentum transfers and excellent signal-to-noise ratio. A horizontal elliptical mirror concept with interchangeable guide pieces will provide high flexibility in beam divergence to allow for a high-resolution powder mode, a high-intensity single crystal mode, and a polarized beam option. A major science focus will be quantum materials that exhibit emergent properties arising from collective effects in condensed matter. The unique use of polarized neutrons to isolate the magnetic signature will provide optimal experimental input to state-of-the-art modeling approaches to access detailed insight into local magnetic ordering.

Wide-angle polarization selectivity based on anomalous defect mode in photonic crystal containing hyperbolic metamaterials.

Conventional defect modes in all-dielectric 1D photonic crystals (PCs) are polarization-insensitive. This poses a great challenge in achieving high-performance polarization selectivity. In this Letter, we introduce a defect layer into a 1D PC containing hyperbolic metamaterials to achieve an anomalous defect mode with polarization-sensitive characteristics. As the incident angle increases, such a defect mode remains almost unshifted under transverse magnetic polarization, while strongly shifting toward shorter wavelengths under transverse electric polarization. The polarization-sensitive characteristics of the defect mode can be well explained by the Fabry-Perot resonance condition. Assisted by the polarization-sensitive defect mode, wide-angle polarization selectivity with an operating angle width up to 54.8° can be realized. Our work provides a route to designing wide-angle linear polarizers using simple 1D structures, which would be useful in liquid crystal display and Q-switched lasers.

Frequency-tunable wide-angle polarization selection with a graphene-based anisotropic epsilon-near-zero metamaterial

In this paper, we achieve frequency-tunable wide-angle polarization selection based on an anisotropic epsilon-near-zero (AENZ) metamaterial mimicked by a subwavelength graphene/SiO2 multilayer. The physical mechanism of wide-angle polarization selection can be explained by the analysis of the iso-frequency curve (IFC). Under transverse electric polarization, only the incident lights which are close to normal incidence can transmit through the designed multilayer since the IFC of the AENZ metamaterial is an extremely small circle. However, under transverse magnetic polarization, all the incident lights can transmit through the designed multilayer since the IFC of the AENZ metamaterial is a flat ellipse. Therefore, polarization selection can work in a broad angular width. By changing the gate voltage applying to the graphene, the operating frequency of polarization selection can be flexibly tuned. The optimal operating angular width of high-performance polarization selection where the polarization selection ratio is larger than 102 reaches 54.9°. This frequency-tunable wide-angle polarization selector would possess potential applications in liquid crystal display, read-write magneto-optical data storage, Q-switched lasing, and chiral molecule detection.

New design of a magnetic device for wide-angle XYZ polarization analysis PASTIS-3, from the concept to first tests with thermal neutrons

We present the new concept and neutron test results of the third generation PASTIS device for XYZ wide-angle polarization analysis for thermal neutrons. PASTIS-3 uses two polarized 3He Neutron Spin filter Cells (NSF) for polarizing and analyzing neutrons spins, flipping the incident neutron beam polarization by reversing the 3He spin state of the polarizing entrance cell. We detail a new coil design for high spatial homogeneity of the magnetic field in any field direction, and the calculation method employed to optimize the geometry and to characterize the field gradients. Various components of the apparatus are described with particular attention to their performance and impact on the relaxation time of the NSF cells. Finally, we present test results of the new device tested on the thermal triple-axis spectrometer IN20 at the ILL.

Complete redshift photonic bandgap and dual-wavelength polarization selection in periodic multilayer structure containing hyperbolic metamaterial

According to the Bragg interference mechanism, photonic bandgaps (PBGs) in conventional all-dielectric periodic multilayer structures shift towards shorter wavelengths (blueshift) as the incident angle increases under both TM and TE polarizations. Hence, the polarization dependence of PBGs in conventional all-dielectric periodic multilayer structures is too weak to realize polarization selection in a broad angle range. Based on the anomalous angle-dependent property of the propagating phase within hyperbolic metamaterial (HMM), we design a complete redshift PBG under TM polarization whose two band edges shift towards longer wavelengths as the incident angle increases in a periodic multilayer structure composed of alternating dielectric and HMM layers. However, the PBG under TE polarization is still blueshifted. As a result, around the long-wavelength and the short-wavelength band edges, efficient polarization selection can be achieved in a broad angle range. This dual-wavelength wide-angle polarization selector based on the complete redshift PBG might possess applications in liquid crystal displays and read–write magneto-optical data storage devices.

Ultra-wideband Transmissive Water-Based Metamaterial Absorber with Wide Angle Incidence and Polarization Insensitivity

A transmissive water-based metamaterial absorber(TWMA) is designed, simulated, and measured, which uses 3D-printing to manufacture. The TWMA uses a circular column and rectangular water layer structure and has no metal backplane. We have proved theoretically and experimentally that the TWMA has absorption rate exceeds 90% in the frequency ranging from 6.5 to 21.4 GHz. Furthermore, the TWMA is thermo-tunable when temperatures change from 10 to 60 °C and has the characteristics of wide angle incidence and polarization insensitivity. It can be applied to a variety of electromagnetic applications, such as reducing broadband scattering and collecting electromagnetic energy in a variable temperature environment.

Wide-angle transmission analyzer for polarized neutrons using equiangular spirals

Much progress in neutron spectroscopy has been achieved with the invention of direct geometry time-of-flight (TOF) spectrometers, which allow an efficient determination of the scattering function S(Q,E) over large ranges in momentum Q and energy E. For separating (i) magnetic from nuclear and (ii) incoherent from coherent scattering, polarization analysis of the scattered neutrons is often required. Typically, the polarization is analyzed by means of 3He spin filters or by curved magnetized mirrors, which are arranged radially around the sample reflecting the spin-up neutrons while the spin-down neutrons are absorbed. In the following we describe the design of a wide-angle polarization analyzer that uses polarizing mirrors with an equiangular profile in transmission, i.e. the spin-down neutrons are transmitted to the detector while the spin-up neutrons are reflected and finally absorbed. Because of the almost constant angle of reflection the bandwidth is large, i.e. it is given by the ratio QP=mmax∕mmin, where mmax and mmin≃0.68 are the maximum and minimum useful m-values of the polarizing supermirror. For small samples and mmax=5, QP=7.4 is achieved. The proposed design eliminates the significant losses of neutrons due to absorption by the front faces of the polarizing blades of wide-angle analyzers in reflection. Moreover, in transmission, the phase space of the neutrons is barely affected by the mirrors and the polarization is rather constant.

Ultra-wideband and wide-angle polarization rotator based on double W-shaped metasurface

In this work, we design a novel polarization converter based on a metasurface with double w-shaped unit cells. The proposed polarization converter can convert linearly polarized incident waves into its cross polarized reflective counterparts in a very wide band with high efficiency. Theoretical analysis and simulation results show that the proposed polarization converter can achieve a 90° polarization rotation, while the polarization conversion ratio (PCR) is above 90% in the frequency range from 8.44 GHz to 24.96 GHz, and the relative bandwidth can be up to 99%. The measured results agree well with simulation results. The designed double w-shaped metasurface has a very simple geometry, and can realize a highly-efficient and broadband polarization rotation. Therefore, it has practical applications in wireless communication systems, imaging, radar stealth technology, and other fields.

Wide-angle polarization analysis on the multi-axis crystal spectrometer for the study of collective and single particle dynamics of methanol at its prepeak

Neutron polarization analysis capability with a large scattering angle and momentum transfer coverage has not been widely implemented for the separation of coherent and incoherent quasi-elastic neutron scattering (QENS) spectra. A feasibility test for soft condensed matter applications was performed on the Multi-Axis Crystal Spectrometer (MACS) at the NIST Center for Neutron Research (NCNR). This capability benefitted from the high flux wide angle polarization analysis capability recently developed on MACS for hard condensed matter investigations. The experimental procedure is thoroughly described on how to take data and perform polarization efficiency correction before further data analysis is done. This capability was employed to unambiguously separate the coherent and incoherent signal from the QENS spectra for the investigation of both the collective and the single particle dynamics in partially deuterated (CH3OD, D 99.5% purity) methanol. By studying a Q range encompassing the prepeak position, it was possible to directly measure the dynamics of the h-bonding associates which originate the prepeak signal, without contamination from the incoherent scattering, in spite of the relative weakness of the coherent scattering.