Showing papers on "Metamaterial absorber published in 2010"
TL;DR: A perfect plasmonic absorber is experimentally demonstrated at lambda = 1.6 microm, its polarization-independent absorbance is 99% at normal incidence and remains very high over a wide angular range of incidence around +/-80 degrees.
Abstract: We experimentally demonstrate a perfect plasmonic absorber at λ = 1.6 μm. Its polarization-independent absorbance is 99% at normal incidence and remains very high over a wide angular range of incidence around ±80°. We introduce a novel concept to utilize this perfect absorber as plasmonic sensor for refractive index sensing. This sensing strategy offers great potential to maintain the performance of localized surface plasmon sensors even in nonlaboratory environments due to its simple and robust measurement scheme.
2,504 citations
TL;DR: In this article, an ultrathin, wide-angle, subwavelength high performance metamaterial absorber for optical frequencies is presented. But the experimental results show that an absorption peak of 88% is achieved at the wavelength of ∼1.58μm, though theoretical results give near perfect absorption.
Abstract: High absorption efficiency is particularly desirable at present for various microtechnological applications including microbolometers, photodectors, coherent thermal emitters, and solar cells. Here we report the design, characterization, and experimental demonstration of an ultrathin, wide-angle, subwavelength high performance metamaterial absorber for optical frequencies. Experimental results show that an absorption peak of 88% is achieved at the wavelength of ∼1.58 μm, though theoretical results give near perfect absorption.
1,147 citations
TL;DR: In this paper, the effect of the surface resistance of the FSS and dielectric substrate characteristics on the input impedance of the absorber is discussed by means of a circuital model.
Abstract: High-impedance surfaces (HIS) comprising lossy frequency selective surfaces (FSS) are employed to design thin electromagnetic absorbers. The structure, despite its typical resonant behavior, is able to perform a very wideband absorption in a reduced thickness. Losses in the frequency selective surface are introduced by printing the periodic pattern through resistive inks and hence avoiding the typical soldering of a large number of lumped resistors. The effect of the surface resistance of the FSS and dielectric substrate characteristics on the input impedance of the absorber is discussed by means of a circuital model. It is shown that the optimum value of surface resistance is affected both by substrate parameters (thickness and permittivity) and by FSS element shape. The equivalent circuit model is then used to introduce the working principles of the narrowband and the wideband absorbing structure and to derive the best-suited element for wideband absorption.
612 citations
TL;DR: In this article, a dual band metamaterial absorber with two distinct absorption peaks of 0.85 at 1.4 THz and 0.94 at 3.0 THz is presented.
Abstract: We present the design, fabrication and characterization of a dual band metamaterial absorber which experimentally shows two distinct absorption peaks of 0.85 at 1.4 THz and 0.94 at 3.0 THz. The dual band absorber consists of a dual band electric-field-coupled (ELC) resonator and a metallic ground plane, separated by an 8 µm dielectric spacer. Fine tuning of the two absorption resonances is achieved by individually adjusting each ELC resonator geometry.
485 citations
TL;DR: In this article, a dual-band metamaterial absorber with two perfect absorption points near 11.15GHz and 16.01GHz was designed and measured in the microwave region.
Abstract: In this paper, we present the design, simulation, and measurement of a dual-band metamaterial absorber in the microwave region. Simulated and experimental results show that the absorber has two perfect absorption points near 11.15GHz and 16.01GHz. Absorptions under difierent polarizations of incident EM waves are measured with magnitude of over 97% at low-frequency peak and 99% at high-frequency peak respectively. Current distribution at the dual absorptive peaks is also given to study the physical mechanism of power loss. Moreover, it is verifled by experiment that the absorptions of this kind of metamaterial absorber remain over 90% at the low-frequency peak and 92% at the high-frequency peak with wide incident angles ranging from 0 - to 60 - for both transverse electric wave and transverse magnetic wave.
295 citations
TL;DR: In this article, the authors reported the first experimental demonstration of an omnidirectional electromagnetic absorber in the microwave frequency, composed of non-resonant and resonant metamaterial structures, which can trap and absorb electromagnetic waves coming from all directions spirally inwards without any reflections due to the local control of electromagnetic fields.
Abstract: In a recent theoretical work by Narimanov and Kildishev (2009 Appl. Phys. Lett. 95 041106) an optical omnidirectional light absorber based on metamaterials was proposed, in which theoretical analysis and numerical simulations showed that all optical waves hitting the absorber are trapped and absorbed. Here we report the first experimental demonstration of an omnidirectional electromagnetic absorber in the microwave frequency. The proposed device is composed of non-resonant and resonant metamaterial structures, which can trap and absorb electromagnetic waves coming from all directions spirally inwards without any reflections due to the local control of electromagnetic fields. It is shown that the absorption rate can reach 99 per cent in the microwave frequency. The all-directional full absorption property makes the device behave like an 'electromagnetic black body', and the wave trapping and absorbing properties simulate, to some extent, an 'electromagnetic black hole.' We expect that such a device could be used as a thermal emitting source and to harvest electromagnetic waves.
267 citations
TL;DR: A photonic metamaterial is demonstrated that shows extraordinary sensitivity to the presence of a single atomic layer of graphene on its surface at the resonance frequency linked to the Fano-type plasmonic mode supported by the periodic metallic nanostructure.
Abstract: We demonstrate a photonic metamaterial that shows extraordinary sensitivity to the presence of a single atomic layer of graphene on its surface. Metamaterial's optical transmission increases multi-fold at the resonance frequency linked to the Fano-type plasmonic mode supported by the periodic metallic nanostructure. The experiments were performed with chemical vapor deposited (CVD) graphene covering a number of size-scaled metamaterial samples with plasmonic modes at different frequencies ranging from 167 to 187 Thz.
234 citations
TL;DR: In this paper, a controllable electromagnetic wave reflector/absorber for different polarizations with metamaterial involving electromagnetic resonant structures coupled with diodes was demonstrated, which can switch the structure between nearly total reflection and total absorption of a particularly polarized incident wave.
Abstract: We demonstrate a controllable electromagnetic wave reflector/absorber for different polarizations with metamaterial involving electromagnetic resonant structures coupled with diodes. Through biasing at different voltages to turn ON and OFF the diodes, we are able to switch the structure between nearly total reflection and total absorption of a particularly polarized incident wave. By arranging orthogonally orientated resonant cells, the metamaterial can react to different polarized waves by selectively biasing the corresponding diodes. Both numerical simulations and microwave measurements have verified the performance.
220 citations
TL;DR: In this article, a polarization insensitive microwave absorber based on metamaterials was designed and fabricated to achieve high microwave absorption up to 97% for difierent polarized incident electromagnetic waves.
Abstract: This paper presents the design, fabrication and measure- ment of a polarization insensitive microwave absorber based on meta- material. The unit cell of the metamaterial consists of four-fold rota- tional symmetric electric resonator and cross structure printed on each side of a print circuit board to realize both electric and magnetic reso- nances to achieve e-cient absorption of the incident microwave energy. Both the full wave electromagnetic simulation and the measurement on the fabricated absorber demonstrate high microwave absorption up to 97% for difierent polarized incident electromagnetic waves. To under- stand the mechanism, analysis is carried out for the electromagnetic fleld distribution at the resonance frequency which reveals the work- ing mode of the metamaterial absorber. Moreover, it is verifled by experiment that the absorption of this kind of metamaterial absorber remains over 90% with wide incident angle ranging from 0 - to 60 - for both transverse electric wave and transverse magnetic wave.
205 citations
TL;DR: In this paper, a broadband gigahertz region metamaterial absorber with a maximum absorption of 99.9% at 2.4 GHz and a full width at half maximum bandwidth of 700 MHz, all while maintaining low reflection inside and outside of resonance.
Abstract: Artificially engineered metamaterials have enabled the creation of electromagnetic materials with properties not found in nature. Recent work has demonstrated the feasibility of developing high performance, narrowband electromagnetic absorbers using such metamaterials. These metamaterials derive their absorption properties primarily through dielectric loss and impedance matching at resonance. This paper builds on that work by increasing the bandwidth through embedding resistors into the metamaterial structure in order to lower the Q factor and by using multiple elements with different resonances. This is done while maintaining an impedance-matched material at normal incidence. We thus present the design, simulation, and experimental verification of a broadband gigahertz region metamaterial absorber, with a maximum absorption of 99.9% at 2.4 GHz, and a full width at half maximum bandwidth of 700 MHz, all while maintaining low reflection inside and outside of resonance.
182 citations
TL;DR: In this article, the near-field interaction between the resonant subwavelength elements of a metamaterial was analyzed and a method to calculate the electric and magnetic interaction coefficients was presented.
Abstract: We analyze the near-field interaction between the resonant subwavelength elements of a metamaterial and present a method to calculate the electric and magnetic interaction coefficients. We show that by adjusting the relative configuration of the neighboring split ring resonators it becomes possible to manipulate this near-field interaction, and thus tune the response of metamaterials. We use the results of this analysis to explain the experimentally observed tuning of microwave metamaterials.
TL;DR: This paper shows that customised broadband absorption of electromagnetic waves having arbitrary polarisation is possible by use of lossy cut-wire (CW) metamaterials and how with proper design a broad range of absorber characteristics may be obtained.
Abstract: This paper shows that customised broadband absorption of electromagnetic waves having arbitrary polarisation is possible by use of lossy cut–wire (CW) metamaterials. These useful features are confirmed by numerical simulations in which different lengths of CW pairs are combined as one periodic metamaterial unit and placed near to a perfect electric conductor (PEC). So far metamaterial absorbers have exhibited some interesting features, which are not available from conventional absorbers, e.g. straightforward adjustment of electromagnetic properties and size reduction. The paper shows how with proper design a broad range of absorber characteristics may be obtained.
TL;DR: A metamaterial consisting of cut-wire structures which shows near-perfect absorption at microwave frequencies is reported, and the analysis of the spectra and retrieved electromagnetic parameters demonstrate that the mismatch is attributed to the considerable influence of the dielectric loss on the strength of the electric and magnetic resonances.
Abstract: The authors report a metamaterial (MM) consisting of cut-wire structures which shows near-perfect absorption at microwave frequencies. Experimental results show slight lower performance than simulation. The analysis of the spectra and retrieved electromagnetic parameters demonstrate that the mismatch is attributed to the considerable influence of the dielectric loss on the strength of the electric and magnetic resonances, which largely determines the ability of the MM absorber. Such dependence on dielectric loss provides an important clue for the design of MM absorber aiming at specific applications where high efficiency energy collection in dielectric is needed.
TL;DR: In this paper, it was shown both numerically and experimentally that the basic dispersion constraints of any passive medium might be overcome by using an active transmission line-based metamaterial.
TL;DR: In this article, a terahertz metamaterial with wire diameters down to ∼10μm and lattice constants of ∼100μm was constructed using drawing.
Abstract: Electromagnetic metamaterials attract much attention since they can be engineered to exhibit optical properties not found in nature. Their fabrication, however, is challenging, especially in volume. We introduce drawing as a means of fabricating metamaterials, thus demonstrating a terahertz metamaterial. We codraw polymethyl-methacrylate and indium, producing several meters of metamaterial with wire diameters down to ∼10 μm, and lattice constants of ∼100 μm. We experimentally characterize the transmission properties of different samples, observing high-pass filtering between 0.3–0.4 THz, in good agreement with simulations.
TL;DR: In this article, a design for metamaterial absorber which is resonant with strong absorbance in the microwave frequency range is presented, which consists of two resonators and a metal wire that couple separately so as to absorb all incident electric and magnetic fields within a single planar layer.
Abstract: We present a design for metamaterial absorber which is resonant with strong absorbance in the microwave frequency range. Our fabricated design consists of two resonators and a metal wire that couple separately so as to absorb all incident electric and magnetic fields within a single planar layer which is only 0.9 mm thick. Experiments demonstrate that the transmission coefficients ( S 21 ) are lower than −10 dB across the entire measurement frequency range and the reflectance coefficients ( S 11 ) are about −20 dB around 10.4 GHz. The absorptivity which can be obtained through S parameters is greater than 98% around 10.4 GHz in experiments and 99.9% in simulations.
TL;DR: In this article, the authors designed, implemented, and experimentally characterized electrically thin microwave absorbers by using the metamaterial concept, which consist of a metal back plate and an artificial magnetic material layer; a metam material back plate, and a resistive sheet layer.
Abstract: We designed, implemented, and experimentally characterized electrically thin microwave absorbers by using the metamaterial concept. The absorbers consist of (i) a metal back plate and an artificial magnetic material layer; (ii) metamaterial back plate and a resistive sheet layer. We investigated absorber performance in terms of absorbance, fractional bandwidth, and electrical thickness, all of which depend on the dimensions of the metamaterial unit cell and the distance between the back plate and metamaterial layer. As a proof of concept, we demonstrated a λ/4.7 thick absorber of type I, with a 99.8% absorption peak along with a 8% fractional bandwidth. We have shown that as the electrical size of the metamaterial unit cell decreases, the absorber electrical thickness can further be reduced. We investigated this concept by using two different magnetic metamaterial inclusions: the split-ring resonator (SRR) and multiple SSR (MSRR). We have also demonstrated experimentally a λ/4.7 and a λ/4.2 thick absorber...
TL;DR: A fabrication technique called membrane projection lithography (MPL) is introduced which combines planar lithography with a sequence of processing steps to create micrometer-scale structures with out-of-plane components.
Abstract: Fabrication of composite materials with designed constituent elements of sub-micrometer size typically requires cutting edge lithography techniques such as immersion lithography, [ 4 ] nanoimprint lithography, [ 5 ] or e-beam lithography. [ 6 ] While these techniques are capable of printing features with the requisite lateral dimensions, they are all planar patterning approaches, and hence offer limited options for creation of 3D structures, or structures with out-of-plane components. Other patterning techniques such as interferometric lithography are capable of creating 3D structures, [ 7 ] but are typically limited to periodic patterns, while direct write approaches are serial, [ 8 ] and hence do not scale well, severely limiting the design space. We introduce a fabrication technique called membrane projection lithography (MPL) which combines planar lithography with a sequence of processing steps to create micrometer-scale structures with out-of-plane components. The method is general, and can be repeated in a layer-by-layer fashion to create 3D volumetric materials with engineered inclusions. The basic premise behind MPL is to create a patterned membrane positioned over a cavity, and then use directional evaporation through the membrane to deposit instances of the membrane pattern on the interior face of the cavity. We fabricate micrometerscale metallic resonators using two separate MPL process fl ows: self-aligned MPL (SAMPL), and single-evaporation MPL (SEMPL). MPL is somewhat related to microstencil fabrication used in micro electromechanical systems (MEMS) fabrication, although the size scale, and linewidths of the patterns we present here are typically at least a factor of 10 smaller than those reported elsewhere. [ 9 ]
TL;DR: In this paper, a dual-band switchable metamaterial electromagnetic absorber with nearly perfect peak absorption was proposed, based on the dipole mode of the electric resonator in the unit cell.
Abstract: This paper presents the design, fabrication and measure- ment of a dual band switchable metamaterial electromagnetic absorber. The unit cell of the metamaterial consists of dipole mode electric res- onators coupled by microwave diodes on one side of a dielectric sub- strate and metallic ground plane on the other side. Simulation and measurement results show that by forward or reverse biasing the diodes so as to change the coupling between the resonators, the absorber can be dynamically switched to operate in two adjacent frequency bands with nearly perfect peak absorption. Field distribution reveals the physical origin of the switchable performance based on the dipole mode of the electric resonator in the unit cell. It is also demonstrated that the frequency difierence between the two bands can be tuned by adjusting the loading positions of the diodes with unchanged high absorption, which helps to design absorbers with speciflc switchable working fre- quencies in practical applications.
TL;DR: Numerical simulations verify that the metamaterial immersion lenses possess exceptionally large effective numerical apertures thus can achieve deep subwavelength resolution focusing and discuss the importance of the losses in modulating the optical transfer function and thus in enhancing the performance of the meetamaterial immersed lenses.
Abstract: We propose and demonstrate metamaterial immersion lenses by shaping plasmonic metamaterials. The convex and concave shapes for the elliptically and hyperbolically dispersive metamaterials are designed using phase compensation method. Numerical simulations verify that the metamaterial immersion lenses possess exceptionally large effective numerical apertures thus can achieve deep subwavelength resolution focusing. We also discuss the importance of the losses in modulating the optical transfer function and thus in enhancing the performance of the metamaterial immersion lenses.
TL;DR: In this paper, a wide-band, polarization-insensitive, wide angle terahertz metamaterial absorber is presented, which can achieve polarization-sensitive, wide-angle absorptions in a wide band from 4.15 to 4.85THz.
Abstract: In this paper, a wide-band, polarization-insensitive, wide- angle terahertz metamaterial absorber is presented. Simulated results show that the absorber can achieve polarization-insensitive, wide-angle absorptions in a wide band from 4.15 to 4.85THz. The retrieved impedance shows that the impedance of the absorber could be tuned, in the absorption band, to match approximatively that of free space on one side and to mismatch on the other side, rendering both the re∞ectance and transmission minimal and thus the corresponding absorbance maximal. The simulated absorbances under three difierent
TL;DR: In this paper, the authors investigated random dendritic cells at microwave frequencies and found that the absorptivities come weaker and the resonant frequency gets red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%.
Abstract: The metamaterial absorber composed of random dendritic cells has been investigated at microwave frequencies. It is found that the absorptivities come to be weaker and the resonant frequency get red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%. The disordered structures can help understanding of the metamaterial absorber and may be employed for practical design of infrared metamaterial absorber, which may play important roles in collection of radiative heat energy and directional transfer enhancement.
TL;DR: A negative index metamaterial is investigated with a phase-sensitive near-field microscope and the optical phase is measured as a function of distance to observe extremely large spatial phase variations within a single unit cell.
Abstract: With their potential for spectacular applications, like superlensing and cloaking, metamaterials are a powerful class of nanostructured materials. All these applications rely on the metamaterials acting as a homogeneous material. We investigate a negative index metamaterial with a phase-sensitive near-field microscope and measure the optical phase as a function of distance. Close to the metamaterial we observe extremely large spatial phase variations within a single unit cell which vanish on a 200 nm length scale from the sample. These deviations of a state-of-the-art metamaterial from a homogeneous medium can be important for nanoscale applications.
TL;DR: In this paper, a planar metamaterial absorber based on lumped elements is proposed, which shows wide-band polarization-insensitive and wide-angle strong absorption.
Abstract: We present the design of a planar metamaterial absorber based on lumped elements, which shows a wide-band polarization-insensitive and wide-angle strong absorption. This absorber consists of metal electric resonators, the dielectric substrate, the metal film and lumped elements. The simulated absorbances under two different loss conditions indicate that high absorbance in the absorption band is mainly due to lumped resistances. The simulated absorbances under three different load conditions indicate that the local resonance circuit (lumped resistance and capacitance) could boost up the resonance of the whole RLC circuit. The simulated voltage in lumped elements indicates that the transformation efficiency from electromagnetic energy to electric energy in the absorption band is high, and electric energy is subsequently consumed by lumped resistances. This absorber may have potential applications in many military fields.
TL;DR: FDTD simulation proves that there is a strong mutual coupling between 2 SRRs besides a strong localized electric field at the split gap, which can enhance the electric field up to 364 times for tunable, broad band and high sensitivity THz sensing.
Abstract: Planar hybrid metamaterial with different split ring resonators (SRR) structure dimensions are fabricated on silicon substrates by femtosecond (fs) laser micro-lens array (MLA) lithography and lift-off process. The fabricated metamaterial structures consist of: (a) uniform metamaterial with 4 SRRs at same design and dimension as a unit cell and (b) hybrid metamaterial with 4 SRRs at same design but different dimensions as a unit cell. The electromagnetic field responses of these hybrid and single dimension metamaterial structures are characterized using a terahertz (THz) time-domain spectroscopy. Transmission spectra of these metamaterial show that a broader resonance peak is formed when 2 SRRs are close to each other. FDTD simulation proves that there is a strong mutual coupling between 2 SRRs besides a strong localized electric field at the split gap, which can enhance the electric field up to 364 times for tunable, broad band and high sensitivity THz sensing. Meanwhile, the strong coupling effect could lead to the formation of an additional resonance peak at ~0.2 THz in the THz spectra regime.
TL;DR: In this paper, the authors presented the simple designs of metamaterial absorbers which are composed of a periodic array of copper annular (or circular) patches, FR4 substrate, and copper film.
Abstract: We present the simple designs of metamaterial absorbers which are composed of a periodic array of copper annular (or circular) patches, FR4 substrate, and copper film. With appropriate geometrical parameters, these metamaterials can provide the electric and magnetic resonances overlapping in the given frequency range, and the experiments demonstrate the absorptivities of 97.6% and 96.7% with only a single layer of the metamaterial absorber. The surface currents and field distributions of these metamaterials are discussed to look straight into the resonance mechanism. Furthermore, our numerical simulations confirm that these metamaterial absorbers could be operated at wide angles of incidence. The simple and highly symmetric structures of the metamaterial absorbers proposed would greatly accelerate the practical applications in optics and electromagnetics.
TL;DR: In this article, the split ring resonators and complementary split-ring resonators are combined to construct a novel compact composite metamaterial, which exhibits a unique property of blocking electromagnetic wave propagating in two directions near the resonant frequency.
Abstract: This paper reports that the split ring resonators and complementary split ring resonators are compounded to construct a novel compact composite metamaterial. The composite metamaterial exhibits a unique property of blocking electromagnetic wave propagating in two directions near the resonant frequency. An example of two-element microstrip antenna array demonstrates that the developed metamaterial enables array performance that is an improvement in comparison with the traditional one, including mutual coupling suppression of 9.07 dB, remarkable side lobe suppression and gain improvement of 2.14 dB. The mechanism of performance enhancement is analysed based on the electric field and Poynting vector distributions in array. The present work not only is a meaningful exploration of new type composite metamaterial design, but also opens up possibilities for extensive metamaterial applications to antenna engineer.
TL;DR: In this paper, the authors presented a 4 × 4 version transfer matrix method (TMM) to study the scatterings by an anisotropic metamaterial of EM waves with arbitrary propagating directions and polarizations.
Abstract: Polarization is an important characteristic of electromagnetic (EM) waves, and efficient manipulations over EM wave polarizations are always desirable in practical applications. Here, we review the recent efforts in controlling light polarizations with metamaterials, at frequencies ranged from microwave to visible. We first presented a 4 × 4 version transfer matrix method (TMM) to study the scatterings by an anisotropic metamaterial of EM waves with arbitrary propagating directions and polarizations. With the 4 × 4 TMM, we discovered several amazing polarization manipulation phenomena based on the reflection geometry and proposed corresponding model metamaterial systems to realize such effects. Metamaterial samples were fabricated with the help of finite-difference-time-domain (FDTD) simulations, and experiments were performed to successfully realize these ideas at both microwave and visible frequencies. Efforts in employing metamaterials to manipulate light polarizations based on the transmission geometry are also reviewed.
08 Apr 2010
TL;DR: In this article, a terahertz tunable metamaterial filter using microelectromechanical systems (MEMS) structures was presented, which can lower the transmission of interest frequency down to −70 dB.
Abstract: This paper presents a terahertz tunable metamaterial filter using microelectromechanical systems (MEMS) structures. The metamaterial unit cells are tuned by micromachined comb-drive. The metamaterial slab works as a notch filter of THz region, which can lower the transmission of interest frequency down to −70 dB. In the experiment, it measures the tuning range of filter frequency from 3.32 to 3.80 THz. The tunable metamaterial filter has better tunability compared with traditional active metamaterial because the optical property of metamaterial is more sensitive to the change of the unit cell structure.