Dual-band Metamaterial Absorber Research Articles

Right-Angle Shaped Elements as Dual-Band Metamaterial Absorber in Terahertz

Metamaterial absorbers display potential applications in the field of photonics and have been investigated extensively during the last decade. We propose a dual-band resonant metamaterial absorber with right-angle shaped elements (RAEs) in the terahertz range based on numerical simulations. The absorber remains insensitive to a wide range of incidence angles (0°–70°) by showing a minimum absorbance of ~80% at 70°. Furthermore, the proposed absorber is highly independent on any state of polarization of the incidence electromagnetic wave due to the high absorbance, i.e., greater than 80%, recorded for the considered polarization states. To further comprehend the slight variations in absorbance as a function of change in the angle of incidence, the impedance of the structure has been critically examined. The metamaterial absorber is simple in design, and we provide a possible path of fabrication.

Dual-band isotropic metamaterial absorber based on near-field interaction in the Ku band

We numerically and experimentally investigate single-band and dual-band isotropic metamaterial absorbers (IMAs) based on metallic disks. By optimizing the diameter of the metallic disks and the thickness of the dielectric substrate, the single-band IMA is observed at 16.2 GHz with absorptivity of 97%. When adding one disk-pair to the structure, the dual-band IMA is obtained at 12.8 and 15.5 GHz due to the symmetry breaking. The physical mechanics is explained by near-field coupling effect and equivalent LC circuit model. The measurement results performed in the range 12–18 GHz show a good agreement with simulation and theoretical analysis. Our findings demonstrate a new approach to achieve dual-band and multi-band IMAs.

A dual-band metamaterial absorber for graphene surface plasmon resonance at terahertz frequency

Abstract In this paper, we present a dual-band metamaterial absorber for graphene surface plasmon resonance at terahertz frequency. We use the finite difference time domain (FDTD) method to study the absorption characteristics of the homocentric graphene ring and disk nanostructure. These simulation results show that the change of the geometrical parameters and the substrate thickness of the nanostructure can change the absorption characteristics and the emergence of dual-band absorption peaks. Moreover, we study the field distribution of nanodisks with different radius in detail. By changing the Fermi level of graphene, the wavelength of their absorption peaks can be adjusted flexibly. In addition, the proposed dual-band absorber also shows a good angle tolerance for both TE and TM polarizations. By calculation the surface-filled water (n = 1.332) and 25% aqueous glucose solution (n = 1.372) for the metamaterial absorber, the sensitivities of mode I and mode II are 5.0 μm/RIU and 15.0 μm/RIU. These research results will have broad application prospects for sensing and spatial light modulators.

Modulation of the absorption properties of a dual band metamaterial based on VO2 thin films

A temperature tunable dual band metamaterial absorber is designed and fabricated. An absorption peak at 1.08 THz is derived from the localized surface plasmon (LSP) mode, while another absorption peak at 1.75 THz is derived from the cavity resonance mode. When different gases are applied to the sample surface, the amplitude and the resonance frequency of the absorption peak at 1.08 THz are modulated. When different liquids are applied to the sample surface, the amplitude of the absorption peak at 1.08 THz is reduced and the resonance frequency is shifted to lower frequencies. The original resonance properties of the absorption peak at 1.08 THz are basically preserved during the measured temperature increase and decrease. The absorption peak at 1.75 THz is sensitive to changes in temperature. The absorption amplitude and resonance frequency are both controlled in the measured temperature increase and decrease.

A dual-band tunable metamaterial absorber based on pneumatic actuation mechanism

A dual-band tunable metamaterial absorber based on the pneumatic actuation mechanism operating within terahertz region has been proposed, in which particularly designed metal structure and a pneumatic actuator are integrated together to provide a dual-band absorption modulation capability. With this concept, the geometric parameters of the metal structure can be dynamically adjusted through controlling the applied pressure, leading to the tuning on the absorption peaks. Based on Multiphysics simulation, including mechanical and electromagnetic one, the absorption characteristics of current metamaterial absorber as well as the corresponding electric field distribution at individual resonant frequencies under different pneumatic actuation statuses have been studied, and a dual-band absorption modulation property has also been successfully demonstrated.

Design Double Layers Structure Based Dual Band Metamaterial Absorbers for Stealth Applications

Design Double Layers Structure Based Dual Band Metamaterial Absorbers for Stealth Applications

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.

A Dual-Band Compact Metamaterial Absorber with Fractal Geometry

A fractal absorber based on a metamaterial configuration is proposed for dual-frequency operation within the UHF band. The miniaturization skills of the proposed fractal shape are used to design a dual-band metamaterial absorber cell with reduced size (<λ/2 at the two operating frequencies) and a very thin substrate thickness (≅λ/100). A metamaterial absorber panel is realized and experimentally validated. Good agreements between full-wave simulations and measurement results are demonstrated.

Design and Simulation of Dual band metamaterial absorber for single junction solar cells

In this work, a metamaterial absorber is designed with the concept of step impedance resonator (SIR) structure for solar cell applications. The rate of absorption can be improved with the use of metamaterial. The designing concept of the metamaterial and the medium is very important when more efficient properties are needed. This proposed design has the capability to increase the absorption rate over a range of frequency 470THz to 570THz and getting the peak absorption at 520THz. This is a unit cell, consists of three layers, which is the substrate, the intrinsic material and also it consists of the top conducting layer which is filled with other materials. The metamaterial absorber is designed and its parametric study is done in the overall range of frequency 450THz to 750THz with various dimensions and filling materials. The materials like silicon dioxide (SiO2), gallium arsenide (GaAs) and aluminium nitride (AlN) are used as the filling materials with the top conducting layer as it is designed in such a way that can provide better absorption rate. And the variations are represented with the help of absorption and reflection parameters.

A broad dual-band switchable graphene-based terahertz metamaterial absorber

A switchable graphene-based terahertz metamaterial absorber is proposed by using nonstructured graphene loaded with simple dielectric resonators, which can achieve both the broad and dual-band absorption with polarization-independent and wide-angle characteristics. The relative bandwidth of the two bands above 80% absorption reaches 97.8% and 31% in the frequency range of 0.473–1.407 THz and 2.273–3.112 THz, respectively. By changing the chemical potential of graphene, the state of the absorber can be switched from absorption (>80%) to reflection (>91%) over the two broad bands. Physical mechanisms of the broad dual-band switchable absorber are investigated by the impedance matching theory and the coupled-mode theory. The dual bands are caused by the Fabry-Perot resonance of dielectric substrate, the broad and high absorption originates from the appropriate impedance match between the absorber and free space. As the absorber is based on a monolayer nonstructured graphene loaded with simple dielectric resonators, the processing difficulty will be reduced greatly and it is easy to tune it through the bias voltage. This structure provides a new perspective to design broad multi-band absorbers and would have promising applications in multiple amplitude modulators, imaging and sensing.

An ultra-thin dual-band wide-angle polarization-insensitive metamaterial absorber with near-unity absorbance

In this paper, a dual-band metamaterial absorber (MMA) with wide-angle and polarization-insensitivity is proposed. The MMA consists of two copper layers with a layer of FR-4 between them. And its top layer consists of a cross-shaped resonator and a square ring resonator. The calculation result demonstrates that there are two distinct absorption peaks, whose absorptivity are 99.933% at 3.8441 GHz and 99.99% at 9.1094 GHz. And its thickness is only 1.34% of the wavelength of the lowest absorption frequency. The dual-band MMA shows polarization-insensitivity for normal incident wave and shows high absorptivity in a wide incident angle for both TE and TM polarization wave. In addition, we discuss the working mechanism. The influences of main parameters on the dual-band MMA's absorption are also analyzed. The proposed ultra-thin MMA has simple structure and high absorptivity, which has many potential applications, such as thermal radiometer, detection sensor, stealth technology.

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.

Tunable dual-band liquid crystal based near-infrared perfect metamaterial absorber with high-loss metal

ABSTRACTIn this work, a tunable dual-band near-infrared perfect metamaterial absorber formed by combining a highly birefringent nematic liquid crystal with a nanoscale metamaterial cavity arranged in mirror symmetry is designed and numerically investigated. Electromagnetic simulations indicate that the absorbance greater than 99.4% may be achieved at 328 THz and 364 THz. Perfect absorbance results both form the use of highly lossy metal and the optimization of the metamaterial structure. In addition, absorbance of the metamaterial device can be substantially tuned both in terms of its magnitude and wavelength with the spectral tunability up to 8 THz by switching of liquid crystal alignment. The soft-matter-based metamaterial absorbers may pave a crucial role towards various active multifunctional systems working in the near-infrared range.

Photoexcited switchable single-/dual-band terahertz metamaterial absorber

A photoexcited switchable single-/dual-band terahertz metamaterial absorber with polarization-insensitive and wide-angle absorption is reported. Through modulating the conductivity of photosensitive silicon embedded in the resonators, the absorber can realize a switching from a dual-band absorption at 0.929 THz and 1.205 THz with 98.88% and 98.70% absorptivity to a redshift single-band absorption at 0.689 THz with 99.29% absorptivity. Meanwhile, it is also found that a switchable single-/dual-band absorption accompanying blueshift and redshift can be achieved by engineering the embedded position of the photosensitive silicon. Furthermore, the extracted electromagnetic parameters, the distributions of the electric fields and the surface currents under different silicon conductivity are demonstrated to give a physical insight into the absorption mechanism. In addition, the proposed absorber possesses polarization-independent and wide-angle absorption for both TE and TM polarization waves.

Independently controllable dual-band terahertz metamaterial absorber exploiting graphene

In this paper, we demonstrate the design and characterization of a controllable dual-band terahertz metamaterial absorber formed by cascading a Salisbury-screen-like structure based on patterned graphene and a gold-graphene hybrid frequency selective surface. By electrostatically changing the chemical potentials of the graphene layers, absorptivity and operating frequency of the metamaterial absorber can be tuned independently without interference. Simulations indicate the absorptivity of the first absorbing peak can be varied from 35% to greater than 99% at 1.45 THz while the position of the second one can be tuned from 2.85 THz to 3.6 THz continuously with absorptivity of 90%. It provides a new perspective on the design of multiband tunable absorbers, thus promoting the realization of terahertz sensors and detectors for practical applications.

Dual-Band Metamaterial Absorbers in the Visible and Near-Infrared Regions

Metamaterial absorbers have attracted much attention due to their unique ability to achieve nearly perfect absorption in compact structures. Most of the reported metamaterial absorbers exhibit only...

Tuning control of dual-band terahertz perfect absorber based on graphene single layer

A dual-band graphene tunable terahertz metamaterial absorber is designed and numerically analyzed in this paper. The tunable absorber consists of two sizes of graphene square rings and a copper strip layer separated by a silicon dielectric layer in a unit cell. The simulation results demonstrate that the absorption performance of the terahertz absorber can be achieved by combining the absorption peaks induced by different graphene square rings. The absorber can achieve the absorption peaks of 99.8% and 99.9% at 0.74 THz and 1.71 THz, respectively. By changing the Fermi energy EF of the graphene material through modulating the bias voltage, the absorption and spectral position of the proposed absorber can be tuned. The flexible and easy design of the proposed single-layer graphene absorber makes it easier to be used in various metamaterial applications including sensing, imaging and communication.

Comment on Polarization-Adjustable Dual-Band Absorption in GHz-Band Metamaterial, Based on the No-Smoking Symbol

Recently, a polarization-adjustable dual-band metamaterial absorber based on a modified no-smoking symbol was reported by Yoo et al. [J. Korean. phys. Soc. 67, 1651 (2015)]. When the angle (φ) between the y-axis and the incident electric field E is 0°, the proposed absorber based on a modified no-smoking symbol has two resonance absorption peaks, one at 4.59 GHz and the other at 6.75 GHz with absorption of 99% and 84%, respectively, and the high-frequency peak can be controlled by changing φ. In addition, the original author indicated that the absorption effect could be expressed in a split-ring structure and the real no-smoking symbol. In this paper, we express doubt that the design of Yoo et al. is not an absorber. When the missing cross-polarization reflection component is taken into the calculation of the absorption, we confirmed that the absorption peaks were 4.05 GHz and 6.03 GHz with real absorption rates of 36.31% and 34.88%, respectively. Obviously, the proposed absorber cannot act as an absorber.

Swastika-shaped microslots as a dual-band metamaterial absorber in the terahertz range

Metamaterial absorbers deliver potential applications in the field of civil and military products. Herein, we proposed a dual-band metamaterial absorber in a range of terahertz (THz) frequency based on numerical simulations. A novel design of swastika-shaped microslots in aluminum film is introduced that displays two high absorbance peaks at the resonant frequencies of 2.77 THz and 3.42 THz, respectively. The microslots enhance the efficiency of the device by accumulating most of the energy inside the symmetrical organized micro-gaps. Impressively, high absorbance in the range of 100–60% is recorded for a wide range of angle of incidence (0°–70°) of the electromagnetic wave. Furthermore, the calculated absorbance considerably remains insensitive (>80%) to any angle of polarization. To achieve relatively easy and cost-effective fabrication of metamaterial absorbers, the proposed absorber is simply designed with micrometer scale slots that are simply ingrained along only the vertical and horizontal directions in the aluminum film.