Showing papers on "Metamaterial absorber published in 2017"
TL;DR: Due to the simplicity of its geometry structure and its easiness to be fabricated, the proposed high figure of merit and sensitivity sensor indicates a competitive candidate for applications in sensing or detecting fields.
Abstract: A perfect ultra-narrow band infrared metamaterial absorber based on the all-metal-grating structure is proposed. The absorber presents a perfect absorption efficiency of over 98% with an ultra-narrow bandwidth of 0.66 nm at normal incidence. This high efficient absorption is contributed to the surface plasmon resonance. Moreover, the surface plasmon resonance-induced strong surface electric field enhancement is favorable for application in biosensing system. When operated as a plasmonic refractive index sensor, the ultra-narrow band absorber has a wavelength sensitivity 2400 nm/RIU and an ultra-high figure of merit 3640, which are much better than those of most reported similar plasmonic sensors. Besides, we also comprehensively investigate the influences of structural parameters on the sensing properties. Due to the simplicity of its geometry structure and its easiness to be fabricated, the proposed high figure of merit and sensitivity sensor indicates a competitive candidate for applications in sensing or detecting fields.
446 citations
TL;DR: In this paper, a review of acoustic metamaterials is presented based on the physics perspective as the coherent basis of a diverse field of sound absorption, where viscous dissipation and heat conduction at the fluid-solid interface, when expressed through micro-geometric parameters, yield an effective medium description of porous media and microperforated panels as effectual sound absorbers.
Abstract: The recent advent of acoustic metamaterials has initiated a strong revival of interest on the subject of sound absorption. The present review is based on the physics perspective as the coherent basis of this diverse field. For conventional absorbers, viscous dissipation and heat conduction at the fluid-solid interface, when expressed through micro-geometric parameters, yield an effective medium description of porous media and micro-perforated panels as effectual sound absorbers. Local resonances and their geometric and symmetry constraints serve as the framework for surveying a variety of acoustic metamaterial absorbers that can realize previously unattainable absorption spectra with subwavelength-scale structures. These structures include decorated membrane resonators, degenerate resonators, hybrid resonators, and coiled Fabry-Perot and Helmholtz resonators. As the acoustic response of any structure or material must obey the causality principle, the implied constraint—which relates the absorption spectru...
298 citations
TL;DR: In this paper, a metamaterial for simultaneous optical transparency and microwave absorption in broadband is presented, which can be used as an optically transparent radar-wave absorber, making use of windmill-shaped elements with the reflection spectra featured by three absorption bands.
Abstract: We present a metamaterial for simultaneous optical transparency and microwave absorption in broadband, which can be used as an optically transparent radar-wave absorber. The proposed metamaterial absorber is made of windmill-shaped elements with the reflection spectra featured by three absorption bands. By properly tailoring the resonances of the structure, we achieve the optimized metamaterial absorptivity that is greater than 90% from 8.3 to 17.4 GHz. In the meantime, excellent optical transmittance is achieved by use of the indium tin oxide (ITO) film with moderate surface resistance, implying that the optical properties of the metamaterial are hardly affected by the periodic meta-atoms. Both numerical simulations and experimental results demonstrate the good performance of the proposed metamaterial, thereby enabling a wide range of applications such as ultrathin detectors and photovoltaic solar cells in the future.
226 citations
TL;DR: A hybrid acoustic metamaterial is proposed as a new class of sound absorber, which exhibits superior broadband low-frequency sound absorption as well as excellent mechanical stiffness/strength, and it is found that viscous energy dissipation at perforation regions dominates the total energy consumed.
Abstract: A hybrid acoustic metamaterial is proposed as a new class of sound absorber, which exhibits superior broadband low-frequency sound absorption as well as excellent mechanical stiffness/strength. Based on the honeycomb-corrugation hybrid core (H-C hybrid core), we introduce perforations on both top facesheet and corrugation, forming perforated honeycomb-corrugation hybrid (PHCH) to gain super broadband low-frequency sound absorption. Applying the theory of micro-perforated panel (MPP), we establish a theoretical method to calculate the sound absorption coefficient of this new kind of metamaterial. Perfect sound absorption is found at just a few hundreds hertz with two-octave 0.5 absorption bandwidth. To verify this model, a finite element model is developed to calculate the absorption coefficient and analyze the viscous-thermal energy dissipation. It is found that viscous energy dissipation at perforation regions dominates the total energy consumed. This new kind of acoustic metamaterials show promising engineering applications, which can serve as multiple functional materials with extraordinary low-frequency sound absorption, excellent stiffness/strength and impact energy absorption.
156 citations
TL;DR: In this paper, a new type of quad-band terahertz metamaterial absorber based on a common sandwich structure is investigated, which enables near-unity absorption in four distinct peaks by utilizing the dipole and quadrupole resonances of the patterns.
Abstract: A new type of quad-band terahertz metamaterial absorber based on a common sandwich structure is investigated. In sharp contrast to the most previous studies focused on only combining of fundamental resonance (or LC resonance) of the metamaterial structure to obtain the quad-band response, we directly enable near-unity absorption in four distinct peaks by utilizing the dipole and quadrupole resonances of the patterns. The design also has the ability to tune the frequencies of the absorption peaks by merely changing the angle of polarization. The proposed platform has potential application perspectives in imaging, sensing, and detection.
145 citations
TL;DR: In this paper, a planar metasurface fractal cross absorber is proposed for the terahertz (THz) band with high absorption and broadband capability, which is a direct step towards the development of highly sought after detectors and sensing devices.
Abstract: Synthetic fractals inherently carry spatially encoded frequency information that renders them as an ideal candidate for broadband optical structures. Nowhere is this more true than in the terahertz (THz) band where there is a lack of naturally occurring materials with valuable optical properties. One example are perfect absorbers that are a direct step towards the development of highly sought after detectors and sensing devices. Metasurface absorbers that can be used to substitute for natural materials suffer from poor broadband performance, whilst those with high absorption and broadband capability typically involve complex fabrication and design and are multilayered. Here, we demonstrate a polarization-insensitive ultrathin (~λ/6) planar metasurface THz absorber composed of supercells of fractal crosses capable of spanning one optical octave in bandwidth, whilst still being highly-efficient. A sufficiently thick polyimide interlayer produces a unique absorption mechanism based on Salisbury screen and an...
136 citations
TL;DR: A novel MA composed of a periodic array of dielectric cylinder sandwiched by the non-noble metal of nickel (Ni) film is demonstrated and exhibits strong absorptive behavior independent of polarization in the whole visible regime.
Abstract: Broadband metamaterial absorber (MA) in the whole visible regime has attracted an enormous amount of attention for its potential applications in thermophotovoltaic cells, thermal emitters, and other optoelectronic devices. Nonetheless, complicated device configuration is still involved in achieving broadband, polarization-independent MA and it results in a cost-ineffective fabrication process. In this paper, a novel MA composed of a periodic array of dielectric cylinder sandwiched by the non-noble metal of nickel (Ni) film is demonstrated. Experimental results show that the proposed MA exhibits strong absorptive behavior independent of polarization in the whole visible regime (400-700 nm). The absorption still remains 80% when the incident angle is 60°. The proposed fabrication method is well compatible with the conventional soft nano-imprinting lithography technique, thus it is economic and scalable for a large-format substrate. These results provide an alternative method for the realization of high-performance visible light absorber and offer new opportunities for potential applications in related fields.
115 citations
TL;DR: A novel ultra-broadband solar absorber by applying iron in a 2D simple metamaterial structure that can achieve the perfect absorption above 95% covering the wavelength range from 400 to 1500 nm is proposed and numerically investigated.
Abstract: We propose and numerically investigate a novel ultra-broadband solar absorber by applying iron in a 2D simple metamaterial structure. The proposed structure can achieve the perfect absorption above 95% covering the wavelength range from 400 to 1500 nm. The average absorption reaches 97.8% over this wavelength range. The broadband perfect absorption is caused by the excitation of localized surface plasmon resonance and propagating surface plasmon resonance. We first propose and demonstrate that the iron is obviously beneficial to achieve impedance matching between the metamaterial structure and the free space over an ultra-broad frequency band in the visible and near-infrared region, which play an extremely important role to generate an ultra-broadband perfect absorption. In order to further broaden the absorption band, we also demonstrate the perfect absorption exceeding 92% for the 400–2000 nm range by adding the number of metal-dielectric pairs and using both gold and iron simultaneously in the proposed structure. The average absorption of the improved absorber reaches 96.4% over the range of 400–2000 nm. The metamaterial absorbers using iron are very promising for many applications, which can greatly broaden the perfect absorption band in the solar spectrum and, meanwhile, can enormously reduce the cost in the actual production.
111 citations
TL;DR: In this article, a standing-up closed-ring resonators (CRRs) was used to achieve high microwave absorption and high compatibility with optical transparency, enabling wide applications in window glass of stealth armament and electromagnetic compatible buildings/facilities.
Abstract: Optically transparent metamaterial microwave absorbers (MMAs) developed so far unexceptionally encounter an intrinsic contradiction between extending the absorption bandwidth and improving optical transparency, hindering their practical applications This work, in its experiment and calculation, demonstrates an MMA with both broadband microwave absorption and excellent optical transparency by standing-up closed-ring resonators (CRRs) in an indium tin oxide backed Plexiglas board The as-designed MMA shows a strong microwave absorption of 85% covering a wide frequency of 55–197 and 225–275 GHz up to a large incident angle of 70o due to the electric and magnetic resonances caused by the standing-up arrangement of the CRRs, as well as the multiple reflection mechanism Moreover, in sharp contrast to the widely adopted stacking multiple layers at the expense of greatly reduced optical transparency, it has an optical transmittance of around 82%, as calculated by a transfer matrix method The standing-up MMA proposed here provides an effective way to achieve broadband microwave absorption and high compatibility with optical transparency, enabling wide applications in window glass of stealth armament and electromagnetic compatible buildings/facilities
108 citations
TL;DR: In this article, an optically transparent metamaterial with broadband absorption is presented theoretically and demonstrated experimentally, which comprises of structures made of resistive films of indium-tinoxide and exhibits over 10 dB absorption in the frequency range of 6.06-14.66 GHz.
Abstract: In this paper, an optically transparent metamaterial with broadband absorption is presented theoretically and demonstrated experimentally. The design comprises of structures made of resistive films of indium-tin-oxide and the metamaterial exhibits over 10 dB absorption in the frequency range of 6.06–14.66 GHz. The novelty of the structure lies in its large absorption bandwidth along with a reduced thickness and optical transparency compared to broadband absorbers reported earlier. Besides, the proposed design is polarization-insensitive and gives rise to angular independent absorption for both transverse electric and transverse magnetic polarizations. The absorption mechanism in the structure has been studied by deriving an equivalent circuit model as well as analyzing several design parameters. Finally, a prototype of the proposed structure has been fabricated and measured, which shows good agreement with the simulated results.
107 citations
TL;DR: Simulation results indicate that the six-band or nine-band absorber possesses nine distinct resonance bands, and average absorptivities of them are larger than 94.03%.
Abstract: This paper reports on a numerical study of the six-band metamaterial absorber composed of two alternating stack of metallic-dielectric layers on top of a continuous metallic plane. Six obvious resonance peaks with high absorption performance (average larger than 99.37%) are realized. The first, third, fifth, and the second, fourth, sixth resonance absorption bands are attributed to the multiple-order responses (i.e., the 1-, 3- and 5-order responses) of the bottom- and top-layer of the structure, respectively, and thus the absorption mechanism of six-band absorber is due to the combination of two sets of the multiple-order resonances of these two layers. Besides, the size changes of the metallic layers have the ability to tune the frequencies of the six-band absorber. Employing the results, we also present a six-band polarization tunable absorber through varying the sizes of the structure in two orthogonal polarization directions. Moreover, nine-band terahertz absorber can be achieved by using a three-layer stacked structure. Simulation results indicate that the absorber possesses nine distinct resonance bands, and average absorptivities of them are larger than 94.03%. The six-band or nine-band absorbers obtained here have potential applications in many optoelectronic and engineering technology areas.
TL;DR: In this paper, the authors demonstrated a soft water-resonator-based metasurface, which functions as an active absorbing material across an ultrabroadband range of Ku, K, and Ka bands.
Abstract: Metasurface absorbing material, which obtains near-unity electromagnetic absorption through subwavelength artificial structure, plays an important role in the area of stealth and shielding technology, biological imaging, etc. However, they usually suffer from narrow bandwidth and only work on planar surfaces. Here, for the first time, this study demonstrates a soft water-resonator-based metasurface, which functions as an active absorbing material across an ultrabroadband range of Ku, K, and Ka bands. Distinct from conventional metallic metasurface, the water-resonator-based metasurface absorbs the microwave by dielectric magnetic resonance and periodic grating effect, which has a perfect absorptivity of ≈99% and an absorption bandwidth (absorptivity higher than 90%) that covers 78.9% of the central frequency. Furthermore, near-unity absorption is maintained when the soft metasurface material is bent into different curvatures, promising high potential applications for antennas in reducing side lobe radiation, eliminating wall reflection in anechoic chambers, antiradar detection, and stealth.
TL;DR: A tunable cross-shaped metamaterial absorber with different arm lengths driven by this combined metasurface and graphene electrode, which supports a resonant frequency tunable from 0.75 to 1 THz with a high-quality factor.
Abstract: In this paper, few-layer porous graphene is integrated onto the surface of a metasurface layer to provide a uniform static electric field to efficiently control liquid crystal, thereby enabling flexible metamaterial designs. We demonstrate a tunable cross-shaped metamaterial absorber with different arm lengths driven by this combined metasurface and graphene electrode. The resulting absorber supports a resonant frequency tunable from 0.75 to 1 THz with a high-quality factor, and amplitude modulation of ~80% at these frequencies with an applied voltage of 10 V. Furthermore, the near-field intensity and hot spot distribution can be manipulated over a broad range.
TL;DR: A wearable metamaterial microwave absorber (WMMA) for indoor radar clear applications is proposed in this paper, which is composed of two square ring resonators with different sizes, a backing ground plane, and a felt substrate with a 1-mm thickness.
Abstract: A wearable metamaterial microwave absorber (WMMA) for indoor radar clear applications is proposed. The proposed WMMA is composed of two square ring resonators with different sizes, a backing ground plane, and a felt substrate with a 1-mm thickness. All conductive materials were fabricated using conductive textiles. The grid array of different square ring resonators provides a broad absorption band due to two neighboring resonance peaks. The measured results exhibit two absorptivity peaks greater than 90% and a full-width at half-maximum of 18.9% at 9.475 GHz. Also, the proposed WMMA has a high absorptivity regardless of the polarization angle of the electromagnetic waves and the deformation effect.
20 Feb 2017
TL;DR: In this paper, the authors proposed a new architecture that uses a multifunctional metamaterial absorber to directly absorb the incident longwave IR energy in a thin-film lithium niobate layer and also to function as the contacts for the two-terminal detector.
Abstract: Pyroelectric materials enable the construction of high-performance yet low-cost and uncooled detectors throughout the infrared spectrum. These devices have been used as broadband sensors and, when combined with an interferometric element or filter, can provide spectral selectivity. Here we propose the concept of and demonstrate a new architecture that uses a multifunctional metamaterial absorber to directly absorb the incident longwave IR (8–12 μm) energy in a thin-film lithium niobate layer and also to function as the contacts for the two-terminal detector. Our device achieves a narrowband (560 nm FWHM at 10.73 μm), yet highly efficient (86%) absorption. The metamaterial creates high field concentration, reducing temperature fluctuation noise, and lowering device capacitance and loss tangent noise. The metamaterial design paradigm applied to detectors thus results in a very fast planar device with a thermal time constant of 28.9 ms with a room temperature detectivity, D*, of 107 cm W/Hz.
TL;DR: In this paper, a metamaterial absorber (MA) based sensor is designed and analyzed for various important applications including pressure, temperature, density, and humidity sensing, and material parameters, as well as equivalent circuit model have been extracted and explained.
Abstract: A metamaterial absorber (MA) based sensor is designed and analysed for various important applications including pressure, temperature, density, and humidity sensing. Material parameters, as well as equivalent circuit model have been extracted and explained. After obtaining a perfect absorption (PA) at around 6.46 GHz and 7.68 GHz, surface current distributions at resonance points have been explained. Since bandwidth and applicability to different sensor applications are important for metamaterial sensor applications, we have realized distinctive sensor demonstrations for pressure, temperature, moisture content and density and the obtained results have been compared with the current literature. The proposed structure uses the changes on the overall system resonance frequency which is caused by the sensor layer’s dielectric constant that varies depending on the electromagnetic behaviour of the sample placed in. This model can be adapted to be used in sensor applications including industrial, medical and agricultural products.
TL;DR: A simple design of an ultrathin six-band polarization-insensitive terahertz perfect metamaterial absorber, composed of a metal cross-cave patch resonator placed over a ground plane, was proposed and investigated numerically.
Abstract: A simple design of an ultrathin six-band polarization-insensitive terahertz perfect metamaterial absorber (PMMA), composed of a metal cross-cave patch resonator (CCPR) placed over a ground plane, was proposed and investigated numerically The numerical simulation results demonstrate that the average absorption peaks are up to 95% at six resonance frequencies Owing to the ultra-narrow band resonance absorption of the structure, the designed PMMA also exhibits a higher Q factor (>65) In addition, the absorption properties can be kept stable for both normal incident transverse magnetic (TM) and transverse electric (TE) waves The physical mechanism behind the observed high-level absorption is illustrated by the electric and power loss density distributions The perfect absorption originates mainly from the higher-order multipolar plasmon resonance of the structure, which differs sharply from most previous studies of PMMAs Furthermore, the resonance absorption properties of the PMMA can be modified and adjusted easily by varying the geometric parameters of the unit cell
20 Apr 2017
TL;DR: In this article, a metamaterial microelectromechanical system (MEMS) capable of tailoring the energy emitted from a surface, without changing the temperature, but, instead, only altering the spectral emissivity.
Abstract: The marriage of micro/nanoelectromechanical systems with metamaterials offers a viable route to achieving reconfigurable devices, which control the emission of energy. Here we propose and demonstrate the idea of a metamaterial microelectromechanical system (MEMS) capable of tailoring the energy emitted from a surface, without changing the temperature, but, instead, only altering the spectral emissivity. Our metamaterial achieves a range of emissivities equivalent to a nearly 20°C temperature change when viewed with a thermal infrared camera. We tessellate a surface with individually reconfigurable MEMS metamaterial pixels, thus realizing a spatiotemporal emitter capable of displaying thermal infrared patterns up to 110 kHz. Our results may be scaled to nearly any sub-optical range of the electromagnetic spectrum, and validate the potential of MEMS metamaterials to operate as reconfigurable multifunctional devices with unprecedented energy control capabilities.
TL;DR: A wide incidence angle-insensitive metamaterial absorber is proposed using eight-circular-sector (ECS) and shows high absorptivity under oblique incidence of both TE and TM polarization due to ECS.
Abstract: In this paper, a wide incidence angle-insensitive metamaterial absorber is proposed using eight-circular-sector (ECS). Under normal incidence, the proposed absorber shows high absorptivity at different polarizations due to its symmetric geometry. Under oblique incidence, zero-reflection conditions for transverse electric (TE) and transverse magnetic (TM) polarization are different. Nevertheless, the proposed absorber shows high absorptivity under oblique incidence of both TE and TM polarization due to ECS. The performance of the proposed absorber was demonstrated with full-wave simulation and measurements. The simulated absorptivity at the specular angles exceed 90% and the frequency variation is less than 0.7% at approximately 9.26 GHz up to a 70° incidence angle in both TM and TE polarization. We built the proposed absorber on a printed-circuit board with 20 × 20 unit cells, and we demonstrated its performance experimentally in free space. The measured absorptivity at 9.26 GHz for the specular angles is close to 98% for all polarization angles under normal incidence. As the incidence angle is varied from 0° to 70°, the measured absorptivity at 9.26 GHz for the specular angles remain above 92% in both TE and TM polarization.
TL;DR: A metamaterial-based quantum searching simulator may lead to remarkable achievements in wave-based signal processors.
Abstract: Metamaterials, artificially structured electromagnetic (EM) materials, have enabled the realization of many unconventional EM properties not found in nature, such as negative refractive index, magnetic response, invisibility cloaking, and so on. Based on these man-made materials with novel EM properties, various devices are designed and realized. However, quantum analog devices based on metamaterials have not been achieved so far. Here, metamaterials are designed and printed to perform quantum search algorithm. The structures, comprising of an array of 2D subwavelength air holes with different radii perforated on the dielectric layer, are fabricated using a 3D-printing technique. When an incident wave enters in the designed metamaterials, the profile of beam wavefront is processed iteratively as it propagates through the metamaterial periodically. After ≈N roundtrips, precisely the same as the efficiency of quantum search algorithm, searched items will be found with the incident wave all focusing on the marked positions. Such a metamaterial-based quantum searching simulator may lead to remarkable achievements in wave-based signal processors.
TL;DR: Based on the strong position sensitivity of metamaterials’ electromagnetic response, meta-atoms that support strongly localized modes with suspended flat membranes that can be driven electrostatically are combined to maximizes the tunability range for small mechanical displacements of the membranes.
Abstract: The realization of high-performance tunable absorbers for terahertz frequencies is crucial for advancing applications such as single-pixel imaging and spectroscopy. Based on the strong position sensitivity of metamaterials’ electromagnetic response, we combine meta-atoms that support strongly localized modes with suspended flat membranes that can be driven electrostatically. This design maximizes the tunability range for small mechanical displacements of the membranes. We employ a micro-electro-mechanical system technology and successfully fabricate the devices. Our prototype devices are among the best-performing tunable THz absorbers demonstrated to date, with an ultrathin device thickness (~1/50 of the working wavelength), absorption varying between 60% and 80% in the initial state when the membranes remain suspended, and fast switching speed (~27 μs). The absorption is tuned by an applied voltage, with the most marked results achieved when the structure reaches the snap-down state. In this case, the resonance shifts by >200% of the linewidth (14% of the initial resonance frequency), and the absolute absorption modulation measured at the initial resonance can reach 65%. The demonstrated approach can be further optimized and extended to benefit numerous applications in THz technology. A material that can alter its interaction with long-wavelength radiation is constructed by researchers in Australia and the United States. Mingkai Liu et al. have created a structure with electrically tunable terahertz absorption. Terahertz light with wavelengths from 0.1 to 1 millimeter is useful in a variety of applications including security-screening. To improve current technologies, materials with a strong and tunable response are desired. The researchers used a microelectromechanical system (MEMS) to control terahertz absorption in a metamaterial — an array of sub-wavelength structures, the dimensions of which determine how the material interacts with electromagnetic waves. The geometry of the structure realized by the team led by Ilya Shadrivov (Australian National University) and Mariusz Martyniuk (University of Western Australia) is adaptively controlled by applying a voltage, rapidly changing the material terahertz absorption by up to 65%.
TL;DR: In this paper, a triple-band tunable perfect terahertz metamaterial absorber (TMA) was proposed, which is composed of a planar metallic disk resonator array above a conductive ground plane separated with liquid crystal (LC) mixture.
Abstract: We report a compact triple-band tunable perfect terahertz metamaterial absorber (TMA) at the subwavelength scale of thickness, which is composed of a planar metallic disk resonator array above a conductive ground plane separated with liquid crystal (LC) mixture. The calculations of terahertz absorption spectra demonstrate triple near-unity absorption bands in the gap plasmonic resonance coupling regime. Three resonance frequencies of the absorber exhibit continuous linear-tunability as changing the refractive index of LC. Remarkably, each peak absorbance of the triple bands maintains at a level of beyond 99% in the whole tuning operation, and the absorbance can remain more than 90% over a wide range of incident angles. Our work suggests that the LC tunable absorber scheme has the potential to overcome the basic difficulty to perform simultaneously multiband spectral tuning and near-unity absorbance with wide angle of incidence and weak polarization dependence. The proposed LC-tunable multiband perfect TMA is promising in the application of biomolecular spectra-selective terahertz imaging and sensing.
TL;DR: It is demonstrated that a highly polarization-sensitive perfect absorber can be realized by replacing the bottom metallic film with a plasmonic grating, and it is found that the absorption is tunable by changing the polarization.
Abstract: Conventional metamaterial absorbers have multilayer designs, where the dielectric interlayer is sandwiched between a top patterned metallic structure and bottom metallic film Here, we demonstrate that a highly polarization-sensitive perfect absorber canbe realized by replacing the bottom metallic film with a plasmonic grating Designs for broadband and narrowband of wavelength are proposed and numerically investigated The designed absorbers perform high light absorption, which is above 90% over the wavelength range of 04–14 µm for the broadband absorber and 98% for the absorption peak in case of the narrowband design, with a specific polarization of incident light We find that the absorption is tunable by changing the polarization Such absorbers offer new approach for active control of light absorbance with strong impacts for solar energy harvesting, light emitting and sensing
TL;DR: In this article, a multiband absorber based on multi-layered square split ring (MSSR) structure is designed to be used in the frequency bands such as WIMAX, WLAN and satellite communication region.
TL;DR: An ultra-thin multi-band polarization-insensitive metamaterial absorber using a single circular sector resonator (CSR) structure in the microwave region that can remain at a high absorption level for all polarization of bothtransverse-electric and transverse-magnetic modes under normal incidence.
Abstract: We design an ultra-thin multi-band polarization-insensitive metamaterial absorber (MMA) using a single circular sector resonator (CSR) structure in the microwave region. Simulated results show that the proposed MMA has three distinctive absorption peaks at 3.35 GHz, 8.65 GHz, and 12.44 GHz, with absorbance of 98.8%, 99.7%, and 98.3%, respectively, which agree well with an experiment. Simulated surface current distributions of the unit-cell structure reveal that the triple-band absorption mainly originates from multiple-harmonic magnetic resonance. The proposed triple-band MMA can remain at a high absorption level for all polarization of both transverse-electric (TE) and transverse-magnetic (TM) modes under normal incidence. Moreover, by further optimizing the geometric parameters of the CSRs, four-band and five-band MMAs can also be obtained. Thus, our design will have potential application in detection, sensing, and stealth technology.
TL;DR: A series of composite radar absorbing structures with resistive frequency selective surface (FSS) have been designed and optimized in high efficiency using the transfer matrix method together with the adaptive genetic algorithm as mentioned in this paper.
TL;DR: The metamaterial property of proposed absorber unit cell dispersion diagram has been shown and it is shown that the absorber structure offers more than 80% absorptivity at different angle of incidence (up to 60°) under transvers electric and transvers magnetic polarization states.
Abstract: This article claims, an investigation on compact ultrathin triple band polarization independent metamaterial absorber for microwave frequency applications. The proposed absorber unit cell consist of two resonators named as Structure-A and Structure-B. Both the resonators are printed on the upper surface of dual side copper coated FR-4 epoxy glass substrate of thickness 0.8 mm. The proposed absorber structure offers three distinct absorption peaks of 99.67%, 99.48%, and 99.42% with FWHM bandwidth of 170 MHz (4.11-4.28 GHz), 350 MHz (9.17–9.52 GHz), and 480 MHz (11.24–11.72 GHz) at 4.19 GHz, 9.34 GHz, and 11.48 GHz, respectively, under normal incidence. In addition to above, the four fold symmetry of proposed absorber structure make it polarization independent. Proposed absorber structure also offers more than 80% absorptivity at different angle of incidence (up to 60°) under transvers electric and transvers magnetic polarization states. The designed absorber unit cell has compactness of $0.11~\lambda _{0} \times 0.11~\lambda _{0}$ with ultra-thin thickness of $0.0111~\lambda _{0}$ , where $\lambda _{0}$ is the free space wavelength with respect to the lowest absorption peak of 4.19 GHz. Absorption mechanism of proposed unit cell has been discussed with the help of normalized input impedance, electric field distribution, and surface current density plots. In order to discuss the metamaterial property of proposed absorber unit cell dispersion diagram has been shown.
TL;DR: This is the first report on using BP metamaterials in an absorber that operates independent of polarization and in dual bands, and is also polarization independent due to the fourfold rotational structural symmetry.
Abstract: Two-dimensional (2D) black phosphorus (BP) with direct band gap, bridges the characteristics of graphene with a zero or near-zero band gap and transition metal dichalcogenides with a wide band gap. In the infrared (IR) regime, 2D BP materials can attenuate electromagnetic energy due to losses derived from its surface conductivity. This paper proposes an IR absorber based on 2D BP metamaterials. It consists of multi-layer BP-based nano-ribbon pairs, each formed by two orthogonally stacked nano-ribbons. The multi-layer BP metamaterials and bottom gold mirror together form a Fabry-Perot resonator that could completely inhibit light transmission to create strong absorption through the BP metamaterials. Unlike previously reported BP metamaterial absorbers, this new structure can operate at two frequency bands with absorption > 90% in each owning to the first-order and second-order Fabry-Perot resonant frequencies. It is also polarization independent due to the fourfold rotational structural symmetry. To our best knowledge, this is the first report on using BP metamaterials in an absorber that operates independent of polarization and in dual bands.
TL;DR: In this article, a metamaterial absorber is designed, fabricated, and experimentally demonstrated to realize ultra-wideband absorption, which is composed of three layers of square resistive metasurfaces with different dimensions.
Abstract: In this paper, a metamaterial absorber is designed, fabricated, and experimentally demonstrated to realize ultra-wideband absorption, which is composed of three layers of square resistive metasurfaces with different dimensions. Multilayer resistive metasurfaces can not only broaden the absorption bandwidth but also adjust the impedance matching based on multi-resonant modes. The total thickness of the proposed absorber is 3.8 mm, which is only 0.09λ at the lowest frequency. The bandwidth of absorptivity more than 90% is from 7.0 GHz to 37.4 GHz, and the relative absorption bandwidth is about 137%. The proposed absorber has good polarization-insensitiveness and wide incident angle stability. The measured results agree well with the theoretical design and the numerical simulations.
TL;DR: A broadband metamaterial absorber with a single layer of tantalum nitride (Ta2N3) frequency selective surface layer, printed on a foam substrate, is presented and has a potential application in evolving broadband terahertz absorbers and sensors.
Abstract: A broadband metamaterial absorber with a single layer of tantalum nitride (Ta2N3) frequency selective surface layer, printed on a foam substrate, is presented. The proposed design has been numerically examined at the terahertz region. The results have shown that a wideband absorption with absorptivity greater than 90% was achieved in the frequency range 1.17-2.99 THz, and the relative absorption bandwidth was up to 112.97%, which is significantly better than previously reported results. Moreover, the absorber was independent of wave polarization, and a high absorption for a wide range of oblique incidence was achieved. The surface current distribution, the electric field distributions, and the power loss analyses were used to explain the physical mechanism of a wideband absorption. However, the tantalum nitride layer has an important role in the energy absorption. According to the obtained results, the proposed absorber, which is compact and simple to design, has a potential application in evolving broadband terahertz absorbers and sensors.