Dual-band Perfect Metamaterial Absorber Research Articles

Design and experimental validation of a compact dual-band metamaterial perfect absorber for electromagnetic energy harvesting applications

This article introduces, characterizes, and experimentally validates an innovative design for a compact-sized metamaterial (MM) perfect absorber (PA) for electromagnetic (EM) energy harvesting (EH) applications. The absorber design, comprised of three octagonal ring resonators made of annealed copper, incorporates split gaps at 45-degree inclinations within the uppermost and middle resonators. A split strip line connects the inner octagonal ring resonators, while the split gaps of the outermost and inner rings are filled with a 50 Ω resistive load. This structure is made on a Rogers RT5880 substrate, and the back side of the proposed design is entirely coated with annealed copper. The proposed absorber achieves precise impedance matching with free space, facilitating efficient absorption and redirecting EM power toward the resistive loads. The absorber demonstrates absorption peaks of 99.98 % at 2.4 GHz and 99.99 % at 4.9 GHz. In addition, the efficiency of absorption is assessed for different incident (θ) and polarization angles (ϕ) in both the Transverse Electric (TE) and Transverse Magnetic (TM) modes. Simulated harvesting efficiencies of 95.33 % at 2.4 GHz and 95.99 % at 4.9 GHz are recorded. An experimental validation is performed using a 3 × 3 array that measures 30 × 30 mm. The tests are carried out in an anechoic chamber. The measured harvesting efficiencies strongly correlate with the simulated results, indicating the reliability of the proposed design. This absorber's efficiency and compact size make it an excellent option for EH systems in wireless sensor networks (WSNs).

Design and analysis of K and Ku-band wide-angle polarization-insensitive dual-band perfect metamaterial absorber

This paper presents a polarization-insensitive dual-band metamaterial perfect absorber applied to the Ku and K bands. The proposed dual-band metamaterial absorber (MMA) is a three-layer structure of metal-dielectric-metal. The top metal layer consists of a split circle ring, two intersecting square rings, and a circle ring, the bottom metal layer is made of copper, and the middle dielectric layer is made of FR-4. The simulation results show that the MMA has two absorption peaks at frequencies of 12.06 GHz and 19.07 GHz, with absorption rates of 99.95% and 99.73%, respectively. The MMA exhibits good polarization insensitivity in TE and TM modes. In TE mode, the increase in incident angle significantly broadens the absorption bandwidth. The experimental results verified the dual-band perfect absorption of MMA and the incident angle gain characteristic of TE mode. The proposed dual-band MMA can be applied in related fields such as radar antennas, satellite communication, and sensing.

Polarization-Angle-Insensitive Dual-Band Perfect Metamaterial Absorbers in the Visible Region: A Theoretical Study

Metamaterial absorbers have been studied extensively due to their potential applications in the field of photonics. In this paper, we propose a simulation study of a polarization-angle-insensitive dual-band perfect metamaterial absorber with absorption peaks at 654 and 781 nm, respectively. By adjusting the structure parameters, dielectric thickness, and refractive index, the obtained absorber has high scalability in the visible wavelength region. To further understand the performance of the cross-structure absorber, analysis of its electric and magnetic field distribution shows that it produces two resonance modes leading to different absorption properties. In addition, the position and intensity of the absorption peaks were found to be unchanged with increasing incident polarization angle, indicating that the absorber is insensitive to the polarization of the incident light. The absorber has great flexibility and has good application potential in sensing and detection.

A symmetric plus-shape resonator based dual band perfect metamaterial absorber for Ku band Wireless Applications

In this article, introduce a metamaterial for microwave absorber applications based on a variant of the symmetric plus-shape resonator. This MA has two absorption peaks, making it suitable for Ku frequency band use. The MA unit cell built on a cheap FR4 substrate. The unit cell's resonator is designed in the form of a four-plus-shape with an eight-square-point in one of the corners, and its dimensions have been tweaked to achieve maximum absorption peaks of 99.04%, and 99.90% at 12.32 GHz, and 16.00 GHz, respectively. Analysing the surface current, electric and magnetic fields, permittivity, permeability, and normalised impedance provides insight into the nature of metamaterial and absorber. The incidence and polarization angle insensitivity of the suggested dual-band absorber allows for pretty much constant absorbance efficiency when the angle is changed. Moreover, for both TE mode and TM mode, the developed metamaterial absorber demonstrates near unity absorption for polarization and oblique incident angles up to 90°. These are single negative metamaterial qualities. The fact that the patch as a whole is rotationally symmetrical is one of the most important factors in determining whether or not it will retain its polarization-insensitive quality. Because of its outstanding insensitivity performance and nearly perfect absorption, it could be a good option for use in Ku band applications.

Holy cross-moon shaped dual band perfect metamaterial absorber for C-band application

In this paper, a dual band electromagnetic perfect metamaterial absorber (PMA) is presented for C-band application. This new design comprises of a moon shape and a holy cross shape metal bar which are surrounded by a circular ring resonator (CRR) and an octagonal close ring resonator (OCRR). Flame retardant 4 dielectric material of thickness 1.6 mm is used as a substrate. Commercially available high frequency electromagnetic simulator CST microwave studio used to simulate the proposed unit cell within the frequency range 2–6 GHz. The numerical simulation shows two resonance peaks at 4.10 GHz and 4.96 GHz with excellent absorption rate. The projected PMA exhibits maximum absorption of 99.99 % (4.10 GHz) and 99.57 % (4.96 GHz) in transverse electric (TE) mode at normal incidence angle. The structure of the unit cell was optimized through some recognized parametric studies like design optimization, resonators widths, gaps among resonators etc. The numerical results for 2 × 2 and 4 × 4 arrays are also investigated. The simulated result of 2 × 2 array shows resonance at 4.14 GHz and 4.98 GHz with absorptivity of 99.06 % and 99.58 %, respectively whereas 4.12 GHz and 4.69 GHz with absorptivity of 92.35 % and 97.62 %, respectively for 4 × 4 array. These two results are quite resembled with the unit cell result. The extracted numerical results are tested and authenticated by some validation processes as equivalent circuit modeling through ADS software, and different electromagnetic simulator such as high-frequency structure simulator (HFSS) which is revealed an unimportant disparity. The offered perfect metamaterial absorber is fit for satellite communication, stealth-coating technology, defense and security uses.

A Rectangle-quartet Metamaterial for Dual-band Perfect Absorption in the Visible Region

Based on rectangle-shaped structures, we create a dual-band metamaterial perfect absorber (DMPA) in the optical region. The independent-polarization absorption is a significant advantage as well as the simple integrated progress for constituent materials. In particular, absorption can be obtained to be over 90% in a bandwidth of 140 THz (from 608 THz to 748 THz), which is still remained well in the oblique incident angles for the TE-polarization. Our results can be regarded as the groundwork for the near future applications such as photodetectors, energy converters and more.

Spectrum Absorbency of Metamaterial Perfect Absorber

A triple-band metamaterial perfect absorber was introduced. The single and simple structure based on gold-bar shaped was designed on the 0.018λ Taconic TLY-5. The gold-bar shaped was designed horizontal initially was then being rotated anti-clockwise from0oto 90oto analyze and understand the change of absorption graph. Dual-band perfect metamaterial absorber was achieved at 45o. The fundamental and third harmonic magnetic resonances caused the low and high frequency peaks, respectively. Then, the gold-bar shaped was slotted at both end to create triple-band metamaterial perfect absorber. The slotted gold-bar shaped was evaluated in three absorption peaks: 99.94%, 99.88% and 99.66% at 3.98 GHz, 4.81 GHz and 5.33 GHz, respectively. This, however, moved to the 3.96 GHz, 4.80 GHz and 5.33 GHz with absorbency 99.79%, 99.95% and 99.90% for the measured structure. Both simulated and measure results were achieved absorbency over 99%, which was almost perfect absorption (≈100%). These properties are expected to beused in real-world applications such as satellite and radar communications transmission, particularly in lowering radar cross-section for stealth applications.

Spectrum Absorbency of Metamaterial Perfect Absorber

A triple-band metamaterial perfect absorber was introduced. The single and simple structure based on gold-bar shaped was designed on the 0.018λ Taconic TLY-5. The gold-bar shaped was designed horizontal initially was then being rotated anti-clockwise from0oto 90oto analyze and understand the change of absorption graph. Dual-band perfect metamaterial absorber was achieved at 45o. The fundamental and third harmonic magnetic resonances caused the low and high frequency peaks, respectively. Then, the gold-bar shaped was slotted at both end to create triple-band metamaterial perfect absorber. The slotted gold-bar shaped was evaluated in three absorption peaks: 99.94%, 99.88% and 99.66% at 3.98 GHz, 4.81 GHz and 5.33 GHz, respectively. This, however, moved to the 3.96 GHz, 4.80 GHz and 5.33 GHz with absorbency 99.79%, 99.95% and 99.90% for the measured structure. Both simulated and measure results were achieved absorbency over 99%, which was almost perfect absorption (≈100%). These properties are expected to beused in real-world applications such as satellite and radar communications transmission, particularly in lowering radar cross-section for stealth applications.

Tunable dual-band metamaterial absorber in the infrared range based on split-ring-groove array.

In this paper, we present a tunable dual-band perfect metamaterial absorber working in the infrared band by integrating a metallic split-ring-groove resonator array with a liquid crystal (LC) layer atop a metal substrate. By varying the height of the central nanodisks, the absorptivity of the dual-band absorption peaks can be simultaneously adjusted. The dual-band resonance frequencies of the proposed absorber exhibit continuous tunability by adjusting the refractive index of the LC, which can be controlled by applying external voltage. The mechanism of the perfect absorption is attributed to the gap plasmonic resonance coupling regime. The presented absorber exhibits good tolerance to incidence angles up to 60° and shows polarization dependent performance, which may offer promising applications in sensing, modulator, and optical absorption switching in the infrared regime.

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.

A Tunable “Ancient Coin”-Type Perfect Absorber with High Refractive Index Sensitivity and Good Angular Polarization Tolerance

In this paper, we design and present a graphene-based “ancient coin”-type dual-band perfect metamaterial absorber, which is composed of a silver layer, silicon dioxide layer, and a top “ancient coin” graphene layer. The absorption performance of the absorber is affected by the hollowed-out square in the center of the graphene layer and geometric parameters of the remaining nano disk. The optical properties of graphene can be changed by adjusting the voltage, to control the absorption performance of the absorber dynamically. In addition, the centrally symmetric pattern structure greatly eliminates the polarization angle dependence of our proposed absorber, and it exhibits good angular polarization tolerance. Furthermore, the proposed “ancient coin”-type absorber shows great application potential as a sensor or detector in biopharmaceutical, optical imaging, and other fields due to its strong tunability and high refractive index sensitivity.

An ultrathin and dual band metamaterial perfect absorber based on ZnSe for the polarization-independent in terahertz range

In this work, a new metamaterial design is proposed to yield an ultra-thin and dual band metamaterials perfect absorber (MPA) to be operated in the frequency range from 15 to 35 THz. The proposed structure is consisted of a copper resonator deposited on a very thin Zinc Selenide ZnSe (0.6 μm) substrate, where the backside of the structure is covered with a metal plate to block the transmission of electromagnetic waves. Computer Simulation Technology (CST) was used to design and investigate the proposed structure. The absorption response of the proposed structure was found to be high enough with absorptivity of 98.44 and 99.28 at 22.46 THz and 28.95 THz, respectively. Results showed that the absorber is insensitive to the incident angle of 0°–60° in both transverse electric (TE) and transverse magnetic (TM) modes, respectively. The MPA was seen to be highly independent on the angles of polarization of the incident waves. The working mechanism of the proposed design was revealed by multiple reflection interference theory and a good agreement was confirmed between the calculated and simulated results. The proposed design can be used for possible applications of stealth technology and imaging.

Simulated and experimental verification of the microwave dual-band metamaterial perfect absorber based on square patch with a 450 diagonal slot structure

In this paper, we designed a dual band metamaterial perfect absorber (MPA) for Ku band applications. The overall ultrathin layer of proposed absorber consists of square patch with 450 diagonal slot structure within a copper square patch which loaded on both sides of dielectric thickness 1.6 mm FR-4 substrate. The results show that designed MPA gives two absorption bands at 12.45 and 14.18 GHz and absorption rates are 99.73% and 99.87% respectively. The proposed dual-band absorber has a polarization sensitive characteristic, the absorption performance is almost changing with different polarization angles. Furthermore, resonance centres of two absorption bands can be adjusted by changing related parameters. The novelties of proposed structure are simple, easy fabricate, low cost, durable, suitable for real-time applications and long-term stability considering the fabrication technique and non-destructive measurement method. The dualband absorber can be used in practical applications such as bolometer, EM wave spatial filter and satellite communications.

Tunable dual-band perfect metamaterial absorber based on monolayer graphene arrays as refractive index sensor

In this study, we propose and numerically investigate a tunable dual-band perfect metamaterial absorber that is based on monolayer graphene arrays in the terahertz region. The proposed structure of the metamaterial absorber consists of a perforated graphene disk array on top of a gold ground plate spaced by a SiO2 dielectric substrate. The absorber achieves almost 100% absorption peaks at 4.7 and 10.7 THz. The resonance frequency and intensity can be adjusted by controlling the graphene conductivity and the structural parameters. Moreover, the absorber is insensitive to the variation in incident angle. The presented absorber can work as a refractive index sensor and the sensitivity reaches 0.67 and 2.33 THz/RIU. Furthermore, it has potential applications in communication, and photovoltaic devices because of its flexible design and stable properties.

Comment on "Dual-Band Perfect Metamaterial Absorber Based on an Asymmetric H-Shaped Structure for Terahertz Waves [Materials] (2018) [2193; https://doi.org/10.3390/ma11112193]".

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Dual-Band Infrared Perfect Absorber Based on a Ag-Dielectric-Ag Multilayer Films with Nanoring Grooves Arrays

In this paper, we demonstrate a dual-band metamaterial perfect absorber based on a Ag-dielectric-Ag multilayer nanostructure. The structure of top metal film covers nanoring grooves array. A dielectric layer has a function of confining electromagnetic fields. Theoretical analysis shows that two absorption peaks (1059 nm and 1304 nm) with the absorption of 99.2% and 99.9% have been achieved, respectively. The physical origin of perfect absorption peaks are related to the Fabry-Perot resonance effect and localized surface plasmon resonance (LSPR) of the nanoring grooves. Its perfect absorption and resonance wavelength can be well regulated by adjusting the relevant structural parameters. Additionally, the absorber demonstrates good operation angle-polarization-tolerance at wide incident angles (0–60°). We believe that our design has a promising application in plasmon-enhanced photovoltaic, optical absorption switching, and modulator optical communications in the infrared regime.

Dual-band near-perfect metamaterial absorber based on cylinder MoS[formula omitted]-dielectric arrays for sensors

As a two-dimensional (2D) material, the crystalline monolayer molybdenum disulfide (MoS2) has drawn extensive attention due to its interesting optical, mechanical and thermal properties compatible with many applications. Here, a dual-band perfect metamaterial absorber (PMA) composed of a simple periodically patterned cylinder/square MoS2-dielectric silica (SiO2) arrays supported by a metal ground plane is proposed and studied by using finite-difference time-domain (FDTD) simulations. Numerical results reveal that the absorption spectrum of the MoS2-based structure displays two perfect absorption peaks in the visible–NIR region. The interactions between electromagnetic waves and this PMA structure are analyzed through the field distributions and spectral responses in detail. It is also presented that the peak wavelengths can be tuned by manipulating related structural parameters. Compared with previous dual-band PMA, our absorber has only one shape that can greatly simplify the manufacturing process and the absorber is insensitive to the polarization of incident light. Furthermore, this PMA can work as a refractive index sensor with high performance due to its stable near-unity absorption.

Numerical investigation of a tunable metamaterial perfect absorber consisting of two-intersecting graphene nanoring arrays

In this paper, we report a numerical investigation of tunable dual-band metamaterial perfect absorber (MMPA) consisting of two-intersecting graphene nanorings arrays. The optical absorption performance of absorber is dominated by the inner/outer radius of nanorings and center distance between the two nanorings. For the resonance modes λ1 and λ2, the sensitivity of probing the surrounding refractive index can reach 7.97 μm/RIU and 13.27 μm/RIU respectively. The absorption performance of the under-study graphene nanorings can be flexibly adjusted by modulating the Fermi level of graphene with voltage. Due to excellent wavelength selectivity and high refractive-index sensitivity, the presented tunable dual-band MMPA has great application prospects as sensors in biopharmaceutical, environmental monitoring.

Rectangular cavity-based perfect dual-band absorber with wide incidence angle in terahertz region

In this paper, a dual-band perfect metamaterial absorber(MA) based on rectangular cavity with wide incidence angle is proposed in the terahertz region. The unit of the absorber is composed of three different size rectangular cavities which are placed vertically on a metal plate. The numerical results show that the MA has two distinctive absorption bandwidths from 3.7586 to 4.0977 THz and 5.7635 to 6.0746 THz, respectively, with both absorption rates larger than 90%. Besides, the resonant frequency can be calculated based on rectangular cavity theory, which provides a design guideline for MA of such type. The theoretical predictions of the resonance frequencies have excellent agreements with the simulation ones. What’s more, the physical mechanism of the perfect absorption can be explained based on the distribution of E-field in the absorber and the standing wave theory. Our results provide a new way on realizing perfect absorption based on rectangular cavity.

Dual-Band Perfect Metamaterial Absorber Based on an Asymmetric H-Shaped Structure for Terahertz Waves.

We designed an ultra-thin dual-band metamaterial absorber by adjusting the side strips’ length of an H-shaped unit cell in the opposite direction to break the structural symmetry. The dual absorption peaks approximately 99.95% and 99.91% near the central resonance frequency of 4.72 THz and 5.0 THz were obtained, respectively. Meanwhile, a plasmon-induced transmission (PIT) like reflection window appears between the two absorption frequencies. In addition to theoretical explanations qualitatively, a multi-reflection interference theory is also investigated to prove the simulation results quantitatively. This work provides a way to obtain perfect dual-band absorption through an asymmetric metamaterial structure, and it may achieve potential applications in a variety of fields including filters, sensors, and some other functional metamaterial devices.