Showing papers on "Metamaterial absorber published in 2016"
TL;DR: A dual-band perfect absorber, composed of a periodically patterned elliptical nanodisk graphene structure and a metal ground plane spaced by a thin SiO(2) dielectric layer, is proposed and investigated.
Abstract: In this paper, a dual-band perfect absorber, composed of a periodically patterned elliptical nanodisk graphene structure and a metal ground plane spaced by a thin SiO(2) dielectric layer, is proposed and investigated. Numerical results reveal that the absorption spectrum of the graphene-based structure displays two perfect absorption peaks in the terahertz band, corresponding to the absorption value of 99% at 35μm and 97%at 59μm, respectively. And the resonance frequency of the absorber can be tunned by controlling the Fermi level of graphene layer. Further more, it is insensitive to the polarization and remains very high over a wide angular range of incidence around ±60(0). Compared with the previous graphene dual-band perfect absorption, our absorber only has one shape which can greatly simplify the manufacturing process.
298 citations
TL;DR: In this paper, a novel metamaterial absorber integrated microfluidic (MAIM) sensor is proposed and demonstrated in terahertz (THz) range, where the dielectric layer of the MDM structure is hollow and acts as the microfluideic channel, and greatly confined electromagnetic fields can be obtained in the channel resulting in significantly enhanced interaction between the analytes and the THz wave.
Abstract: Spatial overlap between the electromagnetic fields and the analytes is a key factor for strong light-matter interaction leading to high sensitivity for label-free refractive index sensing Usually, the overlap and therefore the sensitivity are limited by either the localized near field of plasmonic antennas or the decayed resonant mode outside the cavity applied to monitor the refractive index variation In this paper, by constructing a metal microstructure array-dielectric-metal (MDM) structure, a novel metamaterial absorber integrated microfluidic (MAIM) sensor is proposed and demonstrated in terahertz (THz) range, where the dielectric layer of the MDM structure is hollow and acts as the microfluidic channel Tuning the electromagnetic parameters of metamaterial absorber, greatly confined electromagnetic fields can be obtained in the channel resulting in significantly enhanced interaction between the analytes and the THz wave A high sensitivity of 35 THz/RIU is predicted The experimental results of devices working around 1 THz agree with the simulation ones well The proposed idea to integrate metamaterial and microfluid with a large light-matter interaction can be extended to other frequency regions and has promising applications in matter detection and biosensing
193 citations
TL;DR: The design of an ultra-broadband infrared absorber based on metasurface is demonstrated and it is demonstrated that the absorption bandwidth can be greatly expanded by using two layers of metAsurface, i.e. dual-layered absorber.
Abstract: By using sub-wavelength resonators, metamaterial absorber shows great potential in many scientific and technical applications due to its perfect absorption characteristics. For most practical applications, the absorption bandwidth is one of the most important performance metrics. In this paper, we demonstrate the design of an ultra-broadband infrared absorber based on metasurface. Compared with the prior work [Opt. Express22(S7), A1713-A1724 (2014)], the proposed absorber shows more than twice the absorption bandwidth. The simulated total absorption exceeds 90% from 7.8 to 12.1 um and the full width at half maximum is 50% (from 7.5 to 12.5 μm), which is achieved by using a single layer of metasurface. Further study demonstrates that the absorption bandwidth can be greatly expanded by using two layers of metasurface, i.e. dual-layered absorber. The total absorption of the dual-layered absorber exceeds 80% from 5.2 to 13.7 um and the full width at half maximum is 95% (from 5.1 to 14.1 μm), much greater than those previously reported for infrared spectrum. The absorption decreases with fluctuations as the incident angle increases but remains quasi-constant up to relatively large angles.
162 citations
TL;DR: In this paper, a novel and simple design of a triple-band terahertz absorber formed by only an asymmetric cross is presented, and the theoretical results show that the proposed structure has three distinct absorption bands whose peaks are all over 99%.
Abstract: For a general metamaterial absorber, single patterned structure has only one resonance absorption peak. Therefore, a multi-band perfect absorber can be obtained by employing multiple different-sized metallic patterns. However, this kind of design strategy removes the novelty of their resonance mechanism and is also quite troublesome in regard to fabrication. Here, a novel and simple design of a triple-band terahertz absorber formed by only an asymmetric cross is presented. Theoretical results show that the proposed structure has three distinct absorption bands whose peaks are all over 99%. The first two absorption peaks are due to the magnetic resonances of the different sections of the asymmetric cross, and the third peak is based on the surface response of the structure. Moreover, sensing performance of the absorber is investigated in terms of the surrounding index. It is found that the figure of merit and quality factor of the third peak is much larger than those of the first two peaks, which reveals the proposed absorber's, in particular the third resonance mode of the metamaterial, potential applications in sensing and detection.
148 citations
TL;DR: A new “nano–solid-fluid assembly” method using 15-nm TiO2 nanoparticles as building blocks to fabricate the first three-dimensional (3D) all-dielectric metamaterial at visible frequencies demonstrates the potential to develop low-loss nanophotonic devices atvisible frequencies.
Abstract: Although all-dielectric metamaterials offer a low-loss alternative to current metal-based metamaterials to manipulate light at the nanoscale and may have important applications, very few have been reported to date owing to the current nanofabrication technologies. We develop a new “nano–solid-fluid assembly” method using 15-nm TiO2 nanoparticles as building blocks to fabricate the first three-dimensional (3D) all-dielectric metamaterial at visible frequencies. Because of its optical transparency, high refractive index, and deep-subwavelength structures, this 3D all-dielectric metamaterial-based solid immersion lens (mSIL) can produce a sharp image with a super-resolution of at least 45 nm under a white-light optical microscope, significantly exceeding the classical diffraction limit and previous near-field imaging techniques. Theoretical analysis reveals that electric field enhancement can be formed between contacting TiO2 nanoparticles, which causes effective confinement and propagation of visible light at the deep-subwavelength scale. This endows the mSIL with unusual abilities to illuminate object surfaces with large-area nanoscale near-field evanescent spots and to collect and convert the evanescent information into propagating waves. Our all-dielectric metamaterial design strategy demonstrates the potential to develop low-loss nanophotonic devices at visible frequencies.
130 citations
TL;DR: In this paper, a photoexcited broadband switchable metamaterial absorber (MMA) was proposed for the terahertz (THz) regime, which is a periodic array of dielectric substrate sandwiched with metallic four-splits-ring resonator structure and continuous metallic film.
124 citations
TL;DR: In this paper, a dual-band terahertz absorber formed by a patterned U-shaped metallic ring and a metallic ground plane separated by a dielectric layer is presented.
Abstract: We present a novel dual-band terahertz absorber formed by only a patterned U-shaped metallic ring and a metallic ground plane separated by a dielectric layer. Theoretical results show that the proposed absorber has two distinct absorption bands whose peaks are average over 98 %. Different from previous reports by combining the resonances of the complex structure (coplanar super-unit structure or stacked structure) to obtain the dual-band response, the proposed structure utilizes the LC resonance and dipolar response of the single patterned structure and thus making the proposed structure quite easy to be fabricated. The roles of the geometric parameters are investigated to explain the principle of absorption. Furthermore, the proposed concept applies to other types of absorber structure and can be readily extended to other frequency regimes for a host of applications such as detection, imaging, sensing, and selective thermal emitters.
117 citations
TL;DR: In this article, coherent mechanical oscillations are optically driven on a metamaterial absorber that has a voltage-tunable Fano resonance, and optical damping of the mechanical resonance is also achieved.
Abstract: Coherent mechanical oscillations are optically driven on a metamaterial absorber that has a voltage-tunable Fano resonance. Inversely, optical damping of the mechanical resonance is also achieved.
117 citations
TL;DR: In this paper, the authors investigate the imaging capabilities of a one-dimensional, dynamic, metamaterial aperture that operates at the lower part of K-band microwave frequencies (17.5-21.1 GHz).
Abstract: We investigate the imaging capabilities of a one-dimensional, dynamic, metamaterial aperture that operates at the lower part of K-band microwave frequencies (17.5–21.1 GHz). The dynamic aperture consists of a microstrip transmission line with an array of radiating, complementary, subwavelength metamaterial irises patterned into the upper conductor. Diodes integrated into the metamaterial resonators provide voltage-controlled switching of the resonant metamaterial elements between radiating and nonradiating states. Applying a series of on/off patterns to the metamaterial resonators produces a series of distinct radiation patterns that sequentially illuminate a scene. The backscattered signal contains encoded scene information over a set of measurements that can be postprocessed to reconstruct an image. We present a series of design considerations for the dynamic aperture, as well as a series of experimental studies performed using a dynamic aperture prototype. High-fidelity, real-time, diffraction-limited imaging using the prototype is demonstrated. The dynamic aperture suggests a path to fast and reliable imaging with low-cost and versatile hardware, for a variety of applications including security screening, biomedical diagnostics, and through-wall imaging.
110 citations
TL;DR: In this paper, a tunable metamaterial element that can serve as the building block for a dynamically reconfigurable aperture is presented, where the element is patterned into the upper conductor of a microstrip transmission line, providing both a means of exciting the radiating element as well as independent access for biasing circuitry.
Abstract: We present the design of a tunable metamaterial element that can serve as the building block for a dynamically reconfigurable aperture. The element-a complimentary electric-LC (cELC) resonator-is patterned into the upper conductor of a microstrip transmission line, providing both a means of exciting the radiating metamaterial element as well as independent access for biasing circuitry. PIN diodes are connected across the capacitive gaps of the cELC, and a dc bias current is used to switch the junction between conducting and insulating states. The leakage of RF signal through the bias line is mitigated by integration of a radial decoupling stub. The proposed design and operation of the element are demonstrated through full-wave electromagnetic simulations. We discuss the potential application of the cELC element as a building block for metamaterial apertures capable of dynamic beamforming, imaging, or security screening applications.
107 citations
TL;DR: The concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber’s working bandwidth with maintaining the other inherent advantages are suggested and demonstrated.
Abstract: We suggest and demonstrate the concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber's working bandwidth with maintaining the other inherent advantages. As an example, a broadband terahertz perfect absorber is designed to confirm its effectiveness. The absorber's each cell integrates four sectional asymmetric rings, and the entire structure composed of Au and Si3N4 is only 1.9 μm thick. The simulation results show the bandwidth with absorptivity being larger than 90% is extended by about 2.8 times comparing with the conventional square ring absorber. The composable small cell, ultra-thin, and broadband absorption with polarization and incident angle insensitivity will make the absorber suitable for the applications of focal plane array terahertz imaging.
TL;DR: In this article, a novel metamaterial absorber with angular and polarization insensitivity using multilayer technology was proposed, which consists of a split-ring-cross resonator (SRCR) on the middle layer with a metallic ring on the top layer and meander line on the bottom layer.
Abstract: In this letter, we propose a novel metamaterial absorber with angular and polarization insensitivity using multilayer technology. The miniaturized unit cell of the proposed absorber consists of a split-ring-cross resonator (SRCR) on the middle layer with a metallic ring on the top layer and meander line on the bottom layer. Because additional capacitance and inductance are generated by metallic patterns on the top and bottom layers, the resonance frequency is shifted to a lower frequency and the electrical size of the unit cell dramatically decreases. The principle of miniaturizing the unit cell is described in detail by a parametric study, and the performance of the proposed absorber is demonstrated by full-wave simulation and measurement. The proposed absorber can achieve a high absorptivity at 10.28 GHz and maintain it for different polarizations and incidence angles.
TL;DR: In this paper, a new design approach for achieving quadband terahertz metamaterial absorber, formed by an asymmetric resonator and a metallic board separated by a certain thickness dielectric layer, is numerically studied and demonstrated.
Abstract: A new design approach for achieving quadband terahertz metamaterial absorber, formed by an asymmetric resonator and a metallic board separated by a certain thickness dielectric layer, is numerically studied and demonstrated. Results show that the absorber has four high absorption (greater than 98%) resonance bands (or peaks). The physical origin of the absorber is attributed to four different resonance modes of the single-patterned resonator. The proposed device resolves large unit size, complex resonance structure, and time-consuming and costly fabrication steps, which previously reported absorbers frequently encountered. Moreover, the five-band metamaterial absorber can be obtained by further optimizing the parameters of resonator. The proposed absorber has application prospects in many areas such as materials detection, thermal imaging, and biological sensing.
TL;DR: An incident angle- and polarization-insensitive metamaterial absorber for X-band applications that is close to 100% for all the polarization angles under normal incidence and maintained above 90% for both the transverse electric and transverse magnetic modes.
Abstract: In this paper, an incident angle- and polarization-insensitive metamaterial absorber is proposed for X-band applications. A unit cell of the proposed absorber has a square patch at the centre and four circular sectors are rotated around the square patch. The vertically and horizontally symmetric structure of the unit cell enables polarization-insensitivity. The circular sector of the unit cell enables an angle-insensitivity. The performances of the proposed absorber are demonstrated with a full-wave simulation and measurements. The angular sensitivity is studied at different inner angles of the circular sector. When the inner angle of the circular sector is 90°, the simulated absorptivity is higher than 90%, and the frequency variation is less than 0.96% for incident angles up to 70°. The measured absorptivity at 10.44 GHz is close to 100% for all the polarization angles under normal incidence. When the incident angles are varied from 0°– 60°, the measured absorptivity is maintained above 90% for both the transverse electric (TE) and the transverse magnetic (TM) modes.
TL;DR: Recent major advancements in the emerging fields of diagnostics (sensors) and therapeutics involving thin film metamaterials have been reviewed and underlined; discussing their edge over conventional counterpart techniques; concentrating on their design considerations and feasible ways of achieving them.
TL;DR: An analytical and numerical study of a new type of electromagnetic absorber, operating in the infrared and optical regime, is proposed, and an absorption in a wide angle range and for different resonant frequencies with a large frequency bandwidth for small structure thicknesses is obtained.
Abstract: In this paper, an analytical and numerical study of a new type of electromagnetic absorber, operating in the infrared and optical regime, is proposed. Absorption is obtained by exploiting Epsilon-Near-Zero materials. The structure electromagnetic properties are analytically described by using a new closed-form formula. In this way, it is possible to correlate the electromagnetic absorption properties of the structure with its geometrical characteristics. Good agreement between analytical and numerical results was achieved. Moreover, an absorption in a wide angle range (0°-80°), for different resonant frequencies (multi-band) with a large frequency bandwidth (wideband) for small structure thicknesses (d = λp/4) is obtained.
TL;DR: An ultrabroadband microwave metamaterial absorber (MMA) based on an electric split-ring resonator (ESRR) loaded with lumped resistors is presented in this article.
Abstract: An ultrabroadband microwave metamaterial absorber (MMA) based on an electric split-ring resonator (ESRR) loaded with lumped resistors is presented. Compared with an ESRR MMA, the composite MMA (CMMA) loaded with lumped resistors offers stronger absorption over an extremely extended bandwidth. The reflectance simulated under different substrate loss conditions indicates that incident electromagnetic (EM) wave energy is mainly consumed by the lumped resistors. The simulated surface current and power loss density distributions further illustrate the mechanism underlying the observed absorption. Further simulation results indicate that the performance of the CMMA can be tuned by adjusting structural parameters of the ESRR and lumped resistor parameters. We fabricated and measured MMA and CMMA samples. The CMMA yielded below −10 dB reflectance from 4.4 GHz to 18 GHz experimentally, with absorption bandwidth and relative bandwidth of 13.6 GHz and 121.4%, respectively. This ultrabroadband microwave absorber has potential applications in the electromagnetic energy harvesting and stealth fields.
TL;DR: In this article, a terahertz metamaterial absorber with properties of broadband width, polarization-insensitive, wide angle incidence is presented, and a novel combinatorial way which units a nested structure with multiple metal-dielectric layers is proposed.
Abstract: A terahertz metamaterial absorber (MA) with properties of broadband width, polarization-insensitive, wide angle incidence is presented. Different from the previous methods to broaden the absorption width, this letter proposes a novel combinatorial way which units a nested structure with multiple metal-dielectric layers. We numerically investigate the proposed MA, and the simulation results show that the absorber achieves a broadband absorption over a frequency range of 0.896 THz with the absorptivity greater than 90%. Moreover, the full-width at half maximum of the absorber is up to 1.224 THz which is 61.2% with respect to the central frequency. The mechanism for the broadband absorption originates from the overlapping of longitudinal coupling between layers and coupling of the nested structure. Importantly, the nested structure makes a great contribution to broaden the absorption width. Thus, constructing a nested structure in a multi-layer absorber may be considered as an effective way to design broadband MAs.
TL;DR: In this article, a closed ring resonator (CRR)-based quad-band metamaterial absorber is presented, which consists of four separate CRRs which are diagonally connected to square patches enclosed within an individual CRR.
Abstract: Closed ring resonator (CRR)-based quad-band metamaterial absorber is presented. The unit cell of proposed absorber consists of four separate CRRs which are diagonally connected to square patches enclosed within an individual CRR. The structure is fabricated on 0.8 mm-thick FR4 substrate. Simulated peak absorptivities of 98.5, 97.7, 94.8, and 96% are obtained at 4.34, 6.68, 8.58, and 10.64 GHz, respectively. The measured and simulated absorption characteristics of the proposed absorber are in good agreement. The proposed absorber is wide angle and polarisation insensitive and has identical absorption characteristics for both transverse-electric and transverse-magnetic polarised radiations.
TL;DR: In this paper, a metamaterial absorber with a near-perfect absorption peak, which is tunable magnetically in an ultra-wide frequency range from 0.2 to 7.6 GHz, is proposed and fabricated by combining a ferrite with a metastructure.
TL;DR: In this paper, a flexible piezoelectric patch was introduced for sound-insulation metamaterials with the ability of energy harvesting from sound waves, which can achieve an over 20 dB sound transmission loss and maximum energy conversion efficiency up to 15.3% simultaneously.
Abstract: Membrane-type acoustic metamaterials are well known for low-frequency sound insulation. In this work, by introducing a flexible piezoelectric patch, we propose sound-insulation metamaterials with the ability of energy harvesting from sound waves. The dual functionality of the metamaterial device has been verified by experimental results, which show an over 20 dB sound transmission loss and a maximum energy conversion efficiency up to 15.3% simultaneously. This novel property makes the metamaterial device more suitable for noise control applications.
TL;DR: In this article, a novel five-band terahertz metamaterial absorber based on three nested split-ring resonators is proposed, which has five distinctive absorption bands whose peaks are average over 99%.
Abstract: A novel five-band terahertz metamaterial absorber based on three nested split-ring resonators is proposed. It is found that the structure has five distinctive absorption bands whose peaks are average over 99%. Different from previous reports by combing the resonances of the complex structure to obtain the multi-band responses, the proposed five-band absorber uses the hybrid of the LC resonance and dipolar response of the patterned structure, thus making the proposed structure quite easy to be fabricated. Furthermore, the sensing performance of the absorber is analyzed in terms of the over layer and the surrounding index.
TL;DR: This paper designs a metamaterial unit cell that is based on a split ring cross resonator (SRCR) that is insensitive to incident angles when a via array surrounds the SRR, and demonstrates the effect of the via array using full-wave simulations.
Abstract: In this paper, we propose an angle- and polarization-insensitive metamaterial absorber. We design a metamaterial unit cell that is based on a split ring cross resonator (SRCR). We observe that the absorption frequency and absorption ratio are insensitive to incident angles when a via array surrounds the SRR. We demonstrate the effect of the via array using full-wave simulations by comparing the absorptivity of the SRCR with and without the via array. Because of the symmetric geometry, we also realize polarization insensitivity. We build the proposed absorber on a printed-circuit-board with 30 × 30 unit cells, and we demonstrate its performance experimentally in free space. Under normal incidence, the fabricated absorber shows 99.6% absorptivity at 11.3 GHz for all polarization angles, while for oblique incidence, the fabricated absorber maintains an absorptivity higher than 90% for incident angles up to 70° and 60° for transverse magnetic (TM) and transverse electric (TE) modes, respectively.
TL;DR: In this article, a new metamaterial absorber is designed and characterized numerically for the harvesting of solar energy, which is composed of three layers in which the interaction among them gives rise to the plasmonic resonances.
Abstract: A new metamaterial absorber is designed and characterized numerically for the harvesting of solar energy. The design is composed of three layers in which the interaction among them gives rise to the plasmonic resonances. The main operation frequency range of the proposed structure is chosen to be the visible regime. However, the design is also analyzed for the infrared and ultraviolet regimes. In order to characterize the absorber, some parametric studies with respect to the dimensions of the structure are carried out. According to the results, it is found that the proposed metamaterial absorber has 98.2 % absorption capability at 445.85 THz and 99.4 % absorption capability between 624 and 658.3 THz. Moreover, the polarization dependency of the structure is examined and it is found that the design operates well as a perfect absorber with polarization independency for the studied frequency range. As a result, the proposed metamaterial absorber can be used for solar energy harvesting as it provides multiple perfect absorption bands in the visible regime.
TL;DR: In this paper, a dual-band metamaterial absorber based on simple gold nano-rings was proposed, and the average maximum absorption of two bands can be as high as 95.1% (−0.22 dB).
Abstract: For most of the reported metamaterial absorbers, the peak absorption only occurs at one single wavelength. Here, we investigated a dual-band absorber which is based on simple gold nano-rings. Two absorption peaks can be readily achieved in 3–5 µm and 8–14 µm via tuning the width and radius of gold nano-rings and dielectric constant. The average maximum absorption of two bands can be as high as 95.1% (−0.22 dB). Based on the simulation results, the perfect absorber with nano-rings demonstrates great flexibility to create dual-band or triple-band absorption, and thus holds potential for further applications in thermophotovoltaics, multicolor infrared focal plane arrays, optical filters, and biological sensing applications.
TL;DR: In this paper, a novel wide-band metamaterial perfect absorber (MPA) based on concentric Circular Ring Resonator (CRR) topology is proposed for the application to improve the absorbance of solar photovoltaic cells for the visible frequency region.
TL;DR: In this article, the authors proposed a metamaterial absorber design for solar energy harvesting using a simplified and symmetric structure, which consists of three important layers namely, the bottom metallic layer, which is gold lossy, the intermediate layer: made of a lossy dielectric material that is gallium arsenide and patches which formed by a combination of gold and gallium sulfide.
TL;DR: A wideband-switchable metamaterial absorber using liquid metal to reduce RCS both for X-band and C-band, and the switchable Jerusalem cross (JC) resonator is introduced.
Abstract: Metamaterial absorbers can provide good solutions for radar-cross-section (RCS) reduction. In spite of their attractive features of thinness, lightness, and low cost, resonant metamaterial absorbers have a drawback of narrow bandwidth. For practical radar applications, wideband absorbers are necessary. In this paper, we propose a wideband-switchable metamaterial absorber using liquid metal. In order to reduce RCS both for X-band and C-band, the switchable Jerusalem cross (JC) resonator is introduced. The JC resonator consists of slotted circular rings, chip resistors, and microfluidic channels. The JC resonator is etched on a flexible printed circuit board (FPCB), and the microfluidic channels are laser-etched on a polydimethylsiloxane (PDMS) material. The proposed absorber can switch the absorption frequency band by injecting a liquid metal alloy into the channels. The performance of the absorber was demonstrated through full-wave simulation and through measurements employing prototypes. The experimental results showed absorption ratios of over 90% from 7.43 GHz to 14.34 GHz, and from 5.62 GHz to 7.3 GHz, with empty channels and liquid metal-filled channels, respectively. Therefore, the absorption band was successfully switched between the C-band (4–8 GHz) and the X-band (8–12 GHz) by injecting liquid metal eutectic gallium indium alloy (EGaIn) into the channels.
TL;DR: The characteristics of the absorber make the proposed strategy applicable for the design of more general multiband and broadband perfect absorbers and these perfect absorbing metamaterials are found to exhibit excellent performance in refractive index sensing.
Abstract: A triple-band perfect plasmonic metamaterial absorber based on a metal/insulator/metal (MIM) structure is designed A new freedom through tuning the thicknesses of each ring structures is introduced to realize a quasi-three-dimensional perfect absorber at three extinction wavelengths by using the finite difference time domain method The physical machine is explained by the time domain field analyses and the coupled mode theory The characteristics of the absorber make our proposed strategy applicable for the design of more general multiband and broadband perfect absorbers In addition, these perfect absorbing metamaterials are found to exhibit excellent performance in refractive index sensing
TL;DR: In this paper, a photoexcited switchable perfect metamaterial absorber/reflector for terahertz waves was proposed based on a cross-shaped structure (CSS) integrated semiconductor photoconductive silicon (Si).