Polarization-insensitive Metamaterial Absorber Research Articles

Polarization and angular insensitive bendable metamaterial absorber for UV to NIR range

Broadband absorbers are required for solar energy harvesting because they efficiently absorb the incident photon in the wide-ranging solar spectrum. To ensure high absorption of photons, metamaterial absorbers (MMAs) have been a growing area of interest in recent years. In this article, an MMA is proposed using a metal–insulator–metal (MIM) structure (Ni–SiO2–Ni) that shows a near-unity broadband absorption of wavelengths from 300 to 1600 nm, with a 95.77% average absorption and a peak absorption of 99.999% at 772.82 nm. The MMA is polarization insensitive as well as wide incident angle stable. Analysis of the effects of mechanical bending on the absorption of the proposed structure shows that absorption holds satisfactory values at different degrees of mechanical loading. The suggested MMA unit cell structure was computationally simulated using the Finite Integration Technique (FIT) and verified using the Finite Element Method (FEM). To analyze the feasibility of the proposed MMA as a solar cell, it is investigated with the universal AM 1.5 solar spectrum characteristics. Besides solar energy harvesting, the proposed MMA unit cell may be employed in a variety of diverse optical applications, including sensors, detectors, and imaging.

Design and analysis of a polarization-insensitive six-band metamaterial absorber

This paper presents a six-band metamaterial absorber (MMA). It has a three-layer structure: metal-FR-4-metal. The simulation results demonstrate that there are six distinct absorption peaks at 8.94, 16.47, 19.35, 23.61, 27.03 and 27.42 GHz and absorption rates are 99.68%, 99.52%, 99.46%, 99.92%, 99.89% and 96.22%, respectively. Through the analysis of the effects of structure parameters, then optimized them. Then the electric field and surface current distribution has been studied under the normal incident of TE and TM waves. The simulation results illustrate that it is polarization-insensitive and has simple structure and high absorption rate, so it can be applied in electromagnetic stealth, bolometers, sensor and so on.

Multi-Band Polarization Insensitive Ultra-Thin THz Metamaterial Absorber for Imaging and EMI Shielding Applications

this article, a multi-band polarization-insensitive metamaterial absorber is designed for THz imaging and EMI shielding. A unique oval-shaped structure with three circular ring-shaped resonators is proposed with a unit cell dimension of36×36×19.6μm3. The absorbance of the proposed multiband MMA is 98.57%, 90%and 99.85% at 5.58, 7.98-8.84, 11.45THz frequency respectively. Return loss is nearly the same for the changing incident and polarization angle. Therefore, this metamaterial absorber with a wide range of polarization insensitivity is found and it is also suitable for quantum RADAR Imaging, energy harvesting, and optoelectronic devices.

A Dual-Band Polarization Insensitive Metamaterial Absorber with a Single Square Metallic Patch for Sensing Application

A Dual-Band Polarization Insensitive Metamaterial Absorber with a Single Square Metallic Patch for Sensing Application

Polarization insensitivity characterization of dual-band perfect metamaterial absorber for K band sensing applications

Polarization insensitive metamaterial absorbers (MA) are currently very attractive due to their unique absorption properties at different polarization angles. As a result, this type of absorber is widely used in sensing, imaging, energy harvesting, etc. This paper presents the design and characterization of a dual-band polarization-insensitive metamaterial absorber (MA) for K-band applications. The metamaterial absorber consists of two modified split ring resonators with an inner cross conductor to achieve a 90% absorption bandwidth of 400 MHz (21.4–21.8 GHz) and 760 MHz (23.84–24.24 GHz) at transverse electromagnetic (TEM), transverse electric (TE), and transverse magnetic (TM) mode. Polarization insensitivity of different incident angles for TE and TM mode is also investigated, which reveals a similar absorption behavior up to 90°. The metamaterial structure generates single negative (SNG) property at a lower frequency of 21.6 GHz and double negative property (DNG) at an upper frequency of 24.04 GHz. The permittivity and pressure sensor application are investigated for the proposed absorber, which shows its useability in these applications. Finally, a comparison with recent works is also performed to demonstrate the feasibility of the proposed structure for K band application, like sensor, filter, invasive clock, etc.

Design of Si Based Nano Strip Resonator with Polarization-Insensitive Metamaterial (MTM) Absorber on a Glass Substrate

Design of Si Based Nano Strip Resonator with Polarization-Insensitive Metamaterial (MTM) Absorber on a Glass Substrate

Design and analysis of an ultra-thin dual-band wide-angle polarization-insensitive metamaterial absorber for C-band application

This paper presents an ultra-thin metamaterial absorber (MMA) which can execute two absorption peaks in the C-band. It is polarization-insensitive to the incident wave and has the satisfactory absorption under the wide incident angle. The proposed dual-band MMA is a three-layer structure, the top layer is consisted of a central cross resonator and an external circle ring resonator, the bottom layers is made by copper, and the middle layer is filled in the dielectric FR-4. The calculation results show two diverse absorption bands at the resonance frequency of 4.44 GHz and 7.85 GHz, whose absorbance can reach 99.93 % and 99.99 %, respectively. The structure of the proposed MMA is simple and its thickness is only 1.47 % of the wave length at minimal resonance frequency. In addition, the calculation demonstrates the proposed MMA is insensitive to the various angles of polarization, and it also shows the proposed MMA can attain high absorptivity under the wide angles of incidence in TE and TM modes. Furthermore, the absorption mechanism of the proposed MMA is studied, and the specific effect of the geometric parameters of top resonator and the dielectric thickness on absorptivity are also analyzed. At last, the absorption performance of the proposed dual-band MMA is verified by experiments, which is basically consistent with the simulation effect. The proposed MMA can be applied in C-band radar antenna, satellite communication or other relative fields.

Design, fabrication, and characterization of an electromagnetic harvester using polarization-insensitive metamaterial absorbers

Increasing interest has been paid to metamaterial (MTM) absorbers owing to their huge potential in energy harvesting. However, only a few existing absorbers have the ability to harvest energy from arbitrarily polarized waves without assigning diodes to each unit cell, limiting their applicability and lowering the overall efficiency. In this work, we present an electromagnetic (EM) harvester based on MTM absorbers with the capability of doing so. The harvester consists of periodically arranged symmetrical MTM unit cells and two distinct power combiner networks, allowing it to efficiently harvest the power of incident EM waves with random polarization. With an absorption reaching 99%, the absorber possesses the EM-to-alternating current efficiencies of 75% and 78% corresponding to the vertical and horizontal polarization, respectively, while the final EM-to-direct current conversion efficiency can reach up to 55% at an incident power density of 350 mW m−2. The MTM absorber can also be upgraded to incorporate more unit cells, forming a larger structure with an increasing amount of power harvested.

Quad-band polarization-insensitive metamaterial perfect absorber based on bilayer graphene metasurface

In this paper a quad-band, polarization-insensitive metamaterial perfect absorber (MPA) based on bi-layer graphene in the terahertz regime is presented. Initially, four models of the desired structure by using a single-layer graphene metasurface were examined. The results of the proposed four models show that two absorption peaks were finally achieved at frequencies of 3.19 THz and 4.66 THz with the absorption of 99.61% and 99.95%, respectively. Then, by stacking the double layer graphene metasurface, a quad-band perfect absorber with an average absorption of 99.43% at the frequencies of 2.7 THz, 3.19 THz, 3.99 THz and 4.46 THz is obtained for 0.9 eV Fermi energy. Also, physical mechanisms of MPA have been studied by impedance matching theory. The study of the proposed structure with graphene metasurface has the advantage that the resonant frequency can be tunably adjusted without manufacturing again of the proposed structure. Furthermore, the proposed perfect absorber of metamaterial is polarization-insensitive and is more tolerant than the incident angle. The proposed absorber in this paper has potential in filtering, detection, imaging and other applications photodetectors, and other applications.

An ultra-broadband and optically transparent metamaterial absorber based on multilayer indium-tin-oxide structure

In this work, an ultra-broadband and polarization-insensitive metamaterial absorber (MA) with high optical transparency is presented. Indium-tin-oxide (ITO) films are used as frequency selective surfaces in multiple conductive layers and also as the reflective backplane. Numerical simulation analysis demonstrates that the absorptivity of the proposed absorber exceeds 90% in the frequency range from 10 to 75.5 GHz, corresponding to a relative absorption bandwidth of 153%. The proposed structure has a total thickness of 2.9 mm, which is approximately 1/10 of the free space wavelength of its lowest operating frequency. The absorber also has good polarization insensitivity due to its symmetric geometry. Moreover, for TE-polarized waves, the proposed absorber can maintain an absorptivity greater than 70% for frequencies ranging from 10 to 80 GHz as the incident angle is increased to 45°. For TM-polarized waves, it provides absorptivity of more than 80% at incident angles up to 60°. Surface current distribution on each conductive ITO layer was simulated to analyze the absorption mechanism of the MA. A prototype composed of 16 × 16 unit cells was fabricated and the experimental results show a good agreement with the numerical simulations. Due to its ultra-wideband absorption and wide-incident-angle stability, the proposed MA has potential value in electromagnetic applications such as optically transparent EM shielding and microwave radiation protection.

Cross-Shaped Titanium Resonators Based Metasurface for Ultra-Broadband Solar Absorption

We propose a scheme for ultra-broadband and polarization-insensitive metamaterial perfect absorber (PA) by utilizing a thin metal-insulator-metal (MIM) stack, which is comprised of an array of cross-shaped titanium resonators, a silica dielectric spacer, and an opaque titanium slab. The bandwidth of absorption (A) > 90% is up to 2100 nm, ranging from the visible to near infrared region. At the wavelength range of 400-2500 nm, this metamaterial absorber shows strong absorption of electromagnetic waves. The spectral average absorptivity reaches 93.8% and the maximal absorptivity is up to 99.8%. In addition, the simulations show that the absorption remains high over a broad range of incident angles. Additionally, we have investigated the influences of geometries, structural parameters and material features on the absorption properties. The utilization of titanium rather than the noble metals efficiently lowers the fabrication cost and enhances the thermal stability and biocompatibility, thus paving a way to numerous applications such as solar energy harvesting, imaging, infrared detection and bio-medical techniques.

A Broadband Polarized Metamaterial Absorber Driven by Strong Insensitivity and Proximity Effects

Artificial electromagnetic metamaterial produces exotic resonance, extra ordinary characteristics not available in nature, but engineers can inherit the characteristics by controlling and manipulating their structure. This research primarily the design and realization of dual-band, polarization, and incident angle insensitive metamaterial absorber (MA) is presented. By controlling and manipulating the electromagnetic design shape, artificial structure, periodic array pattern, and dielectric layer thickness a significant way to realize high absorption. In order to achieve high absorption a new shape of an octagonal ring (OR), cross-wires (CWs), and cut-off circle (CC) artificial structure have been sensibly selected. The special characteristics of this structure produce a dual resonance and its bandwidth rises compared that of classical absorber. The proposed artificial structure operation suits the Ku-band application, but possible to enhance in $C$ -band. The numerical and experimental results display a dual-band 99.8% at 12.2 GHz and 99.9% at 15.5 GHz resonance is an excellent agreement in theory and numerical analysis. The effects of the constitutive property parameters: dielectric constant ( $\varepsilon $ ), magnetic permeability ( $\mu$ ), and negative refractive index ( $n$ ) are also investigated. The investigation of symmetric design structure shows the polarization-insensitivity and high absorption initiated even in changing the incident angle. Numerical and experimental results confirmed the destructive interference of multiple penetrations are responsible for the near-unity absorption. An excellent agreement in the absorptivity rates that touches near perfection which is prominent for solar cells, detection, and imaging applications.

A Multi-Band Near Perfect Polarization and Angular Insensitive Metamaterial Absorber With a Simple Octagonal Resonator for Visible Wavelength

A multi-band, ultrathin, polarization-insensitive, near-perfect metamaterial absorber (PMA) has been proposed and substantiated numerically for solar thermophotovoltaic (STPV) systems which also can be used in some other applications. This kind of absorber currently drawing massive interest throughout the research of optics. Especially in solar harvesting metamaterial absorbers can give a huge boost in efficiency by intensifying the solar electromagnetic wave. Visible wavelength has been the key focus of the proposed design so that the structure can utilize solar energy proficiently. Aluminum (Al) and Gallium Arsenide (GaAs) have been chosen as materials for their higher electron mobility along with good temperature stability. The PMA is a three-layer metal-dielectric-metal called sandwiched structure. For proper characterization of the PMA absorber, extensive parametric inspections were carried out with underlying physics. The finite integration technique (FIT) in computer simulation technology microwave studio (CST MWS) is used to perform the numerical analysis and for verification finite element method (FEM) in COMSOL Multiphysics has been used along with interference theory model (ITM) for calculating the absorbance. The PMA shows 99.27%, 99.89%, 99.91%, and 99.06% perfect absorption at 454.75nm, 505.53nm, 568.72nm, and 600.85nm resonance wavelength in all three modes of waveguide propagation. The design also exhibits incident wave stability up to 60° for both transverse electric (TE), and transverse magnetic (TM) wave modes. Excellent glucose concentration sensing ability was also observed with the proposed structure. So, the proposed PMA can be implemented in solar energy harvesting devices along with solar sensors or detectors, light trappers, light modulators, or light wavelength detectors.

Highly Transparent Broadband and Polarization-Insensitive Absorber Based on Metasurface

A highly transparent polarization-insensitive metamaterial absorber with wideband microwave absorption is presented. The broadband absorption (6.0~16.7 GHz, absorptance > 85%) is achieved using three patterned resistive metasurfaces. The visible light transmittance of the absorber is as high as 85.7%. The thickness of the absorber is 4.42 mm, which is only 0.088 times of the upper-cutoff wavelength. A prototype sample is fabricated and measured to demonstrate its excellent performance. The experimental results agree well with the simulation results. In view of its wide band absorption, high transmittance, low profile, polarization insensitivity and wide incidence angle stability, the presented absorber has a wide range of potential applications.

Ultra-broadband, wide-angle, and polarization-insensitive metamaterial perfect absorber for solar energy harvesting

An ultra-broadband perfect absorber for visible to near-infrared light utilizing a metamaterial nanostructure is theoretically proposed and numerically analyzed. The absorber consists of a square and plus shape layer of Ti-Al2O3 (top layer) and a thin layer of Cr located on a SiO2 layer over a TiN substrate. By ameliorating the dimensions of the design, an average absorption of 95.4% is attained for wavelengths from 400 to 1800 nm, with a peak absorption of about 100%. Also, the bandwidths corresponding to the absorption above 90% and 99% are 1317 and 773 nm, respectively. The cooperative effects of the corresponding localized plasmonic resonances and the propagating surface plasmons of Ti resonators subsidize to the absorption response. Furthermore, the spectral response of the proposed nanostructure is insensitive to incident angle and independent of polarization angle. The proposed absorber has application prospects in photovoltaic devices, solar energy harvesting, and light trapping.

Design, simulation, and analysis of an ultra-broadband polarization-insensitive terahertz metamaterial absorber

A novel ultra-broadband polarization-insensitive metamaterial absorber is presented in this paper, which can work in the terahertz (THz) regime. By stacking two layers with a certain proportion separated by dielectric spacing layers, on which six nested rings of different sizes and other metal resonators are arranged, the metamaterial absorber for a TE wave can achieve absorption of over 90% at 2.28–5.58 THz, and that for the TM wave is located at 2.3–5.82 THz, whose relative bandwidths (RBWs) are 82.5% and 88%, respectively, which is shown in the simulation results. Moreover, the absorption performance of such an absorber remains stable at 2.3–5.58 THz, whose RBW is 82% when the wave is incident with different polarization angles, which implies that the metamaterial absorber has insensitivity towards polarization. The absorption mechanism for this absorber originates from the Fabry–Perot resonances among different layers and the magnetic resonances among the metal resonators, based on analysis of the distributions of the power loss density, surface current, and magnetic fields. The metamaterial absorber presented in this work is promising for application owing to its broad absorption band and insensitivity towards polarization.

An ultra-thin quad-band metamaterial inspired absorber using symmetric bent-arrow shaped resonator for sensing and imaging in defense applications

In this paper, a novel compact quad-band polarization insensitive metamaterial absorber has been proposed to be employable in the microwave frequency regime. The unit-cell geometry comprises of four symmetric bent-arrow shaped resonators, where each arrow has been bounded by an open ring. The resultant structure is further surrounded by a closed ring to obtain an extra resonance band. Full-wave simulation with normal incidence depicts quad-band operation with absorption peaks at 3.24 GHz (S-band), 6.55 GHz (C-band), 15.22 GHz (Ku-Band), 15.94 GHz (Ku-band) and absorptivity levels of 99.57%, 99.94%, 96.10%, 98.65% correspondingly. It also shows full width half maximum (FWHM) bandwidth of 100 MHz, 200 MHz and 1210 MHz in the first, second and third bands respectively. Furthermore, the proposed structure is based on four-fold symmetry therefore exhibits polarization-insensitive behaviour unlike conventional absorbers. The structure is fabricated on 1 mm FR4 Glass Epoxy substrate equivalent to 0.0108 λ 0 hence, can be used as absorber coating for planar surfaces. The designed absorber has been fabricated and experimental results were in good agreement with the simulated responses enabling its wide application in various technologies like stealth technology, radar cross section reduction, anechoic chambers, electromagnetic interference/electromagnetic compatibility, and radio frequency identification.

Multi-band (9,4) chiral single-walled carbon nanotube based metamaterial absorber for solar cells

A novel multiband (9,4) polarization insensitive metamaterial (MTM) absorber structure based on the vertical nanotubes composited with the silicon dielectric material is proposed in this research. Multiband polarization insensitivity is achieved through the unique geometrical configuration of the design, which provides almost unity absorption in the visible and ultraviolet regions from 300 THz to 1000 THz. The proposed design is selected due to the simplicity of the construction, ease of fabrication and the ability to absorb almost perfectly under changing geometrical parameters. The electromagnetic response of the design is simulated for four maximum absorption peaks at 394.3 THz, 514.9 THz, 632.8 THz, and 773.2 THz with the corresponding absorption rates of 99.8%, 98.35%, 96.66%, and 80.60%, respectively. The sensitivity of the polarization angle of the MTM absorber has also been investigated, which verifies that the current design is insensitive to the different polarization angles. The flexibility of the proposed design has also been investigated by altering the geometrical components, materials, and the dimensions, and it is confirmed that the proposed MTM absorber design provides high absorption rates under all considered circumstances. The MTM absorber designs is found to be capable of improving the efficiency of the solar cell. The implementation of these MTM absorbers in the solar cells can significantly improve the absorption rate by reducing the reflection and transmission. MTM is validated by both prior art investigation and the different solver such as FEM and FIT. Results of interface theory model and simulations are compared against one another, which show good agreement yielding reliable and accurate estimations.

Near-perfect broadband infrared metamaterial absorber utilizing nickel.

We propose a thin, compact, broadband, polarization and angle insensitive metamaterial absorber based on a tungsten reflector, a silicon spacer, and a top pattern composed of a double square-like ring resonator utilizing nickel (Ni). In such a structure, a high absorption (above 80%) bandwidth ∼4.8µm from 3.52 up to 8.32 µm corresponding to the relative bandwidth ∼81% can be achieved with deeply subwavelength unit cell dimensions. Here the physical origin of the broadband absorption is associated with low Q-factor dipole modes of the top pattern inner and outer sides functioning as rectangular nanoantennas. Owing to the structural symmetry, the absorber shows a good incidence angle tolerance in the relatively wide range for both transverse electric and transverse magnetic polarizations. The effective parameters of the Ni-based absorber were retrieved using the constitutive effective medium theory, and the absorption characteristics of the effective medium and metamaterial were compared.

Wideband and polarization-insensitive metamaterial absorber with loading lumped resistors.

IWe have designed, simulated, and experimentally tested a broadband metamaterial absorber loaded with lumped resistors in the microwave range. Compared with an electric resonator structure absorber, the composite absorber loaded with lumped resistors has stronger absorptivity over an extremely extended bandwidth. The simulated results show that an effective absorption bandwidth covers from 7.12 to 8.61 GHz with the absorption rate more than 90% under normal incidence. For oblique incidence, the proposed absorber displays an absorption rate above 90% from 7.55 to 8.61 GHz when the incident angle is below 35° for the transverse electric polarization. About the transverse magnetic polarization, the absorber displays larger than 90% absorptance from 7.24 to 8.61 GHz when the incident angle is below 70°. During the entire design process, the absorber structure is fabricated and measured. The measured results show that the absorptivity is above 90% in the frequency range of 6.78-7.65 GHz and 8.20-9.31 GHz under normal incidence. Furthermore, the absorption mechanism and absorption properties are further researched.