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Broadband perfect absorption enabled by using terahertz metamaterial resonator
摘要： Broadband metamaterial perfect absorbers are of paramount importance in many applications. However, these broadband absorbers are typically based on complex structure designs, the manufacturing process of them is highly challenging. This paper shows that a fairly simple structure formed by a rectangular metallic patch with two rectangular holes backed by two layers of dielectric sheet and metallic mirror is utilized to obtain the broadband absorption. The structure possesses three different but similar resonance peaks, and the superposition of them can realize a bandwidth of 1.00 THz with absorption >80%. The absorber physical origin is elucidated by means of the corresponding field distributions of the three absorption modes. Furthermore, the device bandwidth can be tuned via changing the sizes of the resonator. These absorption properties using the simple structure design can benefit a wide range of applications.
关键词： Metamaterials,Broadband absorption,Terahertz
更新于2025-09-19 17:13:59
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Electromagnetic simulation of MXene-based plasmonic metamaterials with enhanced optical absorption
摘要： In this contribution we propose, design and numerically analyze a plasmonic metamaterial for enhanced optical absorption, based on 100 nm thick titanium carbide (Ti3C2Tx) MXene sheets. The analyzed metamaterial is built as a sandwich with a solid MXene bottom (ground) layer, a lossless dielectric middle layer and an MXene mesh top layer. The unit cell of the periodic top mesh consists of two crossed ultrathin MXene strips, each of them spreading its width in step-like increments towards the middle of the unit cell. This ensures position-variable width of the top surface apertures, resulting in a widening of the bandwidth of spectral dispersion of the scattering parameters of the obtained metamaterial. We utilize the finite element method to simulate the scattering parameters of the MXene-based metamaterial. We apply Drude–Lorentz model to derive our analytical expression for complex permittivity of Ti3C2Tx MXene based on experimental measurements. The described approach is general, since various alternative plasmonic materials can be utilized, including different MXenes, but other materials as well, such as graphene, metals and metal alloys, semiconductors, etc. The approach is applicable to various other nanoplasmonic structures. In this manner the available toolbox for plasmonics is extended and a new degree of design freedom ensured.
关键词： MXenes,Superabsorbers,Nanoplasmonics,Electromagnetic simulation,Metamaterials
更新于2025-09-19 17:13:59
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Ultrabroadband plasmonic induced transparency in random metamaterial with nanocavity
摘要： A three-dimensional (3D) metamaterial is very easily assembled as a stacked structure with two physical vapor deposition layers, one metallic and one dielectric, and with a spray of gold nanospheres (GNS) on top. The first planar metasurface is a semicontinuous gold nanocomposite which is transformed into a “dark metasurface” when embedded in a dielectric nanocavity. The second metasurface is a radiative mirror composed of the self-arranged GNS at the nanocavity’s surface. The two random metasurfaces are strongly coupled through their near field inside the nanocavity. Plasmonic induced transparency is observed at normal incidence over a very wide spectral bandwidth of a few hundred terahertz from the visible to the NIR. The induced transmission maximum occurs in a spectral region where the scattering cross section from the GNS is maximum. Critical coupling between the two metasurfaces is achieved with multiple deposits of GNS and the transition from induced transparency to induced absorption is experimentally observed. Such a simple 3D metamaterial could be used to enhance non-linear optical effects, optical switching and slow light generation in the NIR.
关键词： Plasmonics,Nanocomposites,Nanospheres,Critical coupling,Metamaterials,Nano optics
更新于2025-09-19 17:13:59
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Plasmon Induced Transparency in Graphene-based Side Coupled two Rectangular Nano-cavities-like structures
摘要： We investigate numerically the plasmon analogue of electromagnetic induced transparency (EIT) in a compact graphene-based waveguide coupled to two rectangular nano-cavities-like structures made out of graphene nanoribbons. The cavities are placed symmetrically on each side of the bus waveguide, giving rise to a V-like state in analogy with three level atomic systems. In this configuration, the cavities are directly coupled to the waveguide, and consequently both play the role of the bright mode. By slightly detuning the Fermi energy level of the cavities, we show the possibility of generating a narrow transparency window, that’s, the plasmon induced transparency (PIT). The resonance peak occurs as a consequence of destructive interference between the cavities acting like coupled radiative oscillators. We also demonstrate that by appropriately shifting (symmetrically) the Fermi energy levels of the cavities, one could dynamically tune the resonance peak frequency. The proposed structure may help the design of highly integrated optical devices.
关键词： Nanomaterials,Plasmon induced transparency,Graphene waveguide,Metamaterials,Surface plasmons
更新于2025-09-19 17:13:59
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Tunneling-induced broadband and tunable optical emission from plasmonic nanorod metamaterials
摘要： We demonstrate a metamaterial platform for electrically driven broadband light emission induced by electron tunneling. Both the Fabry-Perot and waveguided modes of the metamaterial slab as well the plasmonic mode of the tunneling gap are identified as contributing to shaping the emission spectrum. This opens up an opportunity to design the spectrum and polarization of the emitted light by tuning the metamaterial modes via the geometric parameters of the nanostructure throughout the visible and near-infrared spectral ranges. The efficient coupling of the tunneling-induced emission to the waveguided modes is beneficial for the development of integrated incoherent light sources, while the outcoupled emission provides a source of free-space radiation. The demonstrated incoherent nanoscale light sources may find applications in the development of integrated optoelectronic circuits, optical sensing platforms, imaging, and metrology.
关键词： plasmonics,nanoscale light sources,metamaterials,electron tunneling
更新于2025-09-19 17:13:59
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The investigation of the electromagnetic coupling effect in terahertz toroidal metasurfaces and metamaterials
摘要： We proposed and fabricated toroidal dipole (TD) metasurfaces(MSs) with a metamolecule of two coplanar U-shaped split ring resonators(USRRs) fabricated on polyimide substrate, and TD metamaterials (MMs) were the stacks of two TD MSs layers, whose frequencies, electromagnetic (EM) distributions and Q factor can be efficiently affected by the EM coupling effect in TD MSs/MMs. It was found that the resonances frequencies of TD MMs were shifted to lower frequencies due to the increase of inductance by the stacks of metallic layer. Meanwhile, the high-frequency TD resonance in TD MMs would be tailored by the periodicity. Considering the relation between TD resonances and the scattering power of TD (Ty), the Q factor depended highly on the value of Ty in the same metamolecule structure. The optimization in excitation of TD provide opportunity to further increase the Q-factor of metamaterial and pave a way for potential applications in terahertz sensor and other functional devices.
关键词： Toroidal dipole,Terahertz,Metamaterials,Metasurfaces
更新于2025-09-19 17:13:59
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Soft Plasmonic Assemblies Exhibiting Unnaturally High Refractive Index
摘要： The increases in refractive indices (n) of materials are crucial for transformative optical technologies. With the progress of monolithic lithography, large advances have been achieved with several semiconductors, including silicon, germanium, and gallium arsenide, which generally provide higher n of ～4.0 compared to those of other elements. Nevertheless, above this upper limit of naturally available n, light?matter interactions could be unprecedentedly expanded, which in turn enriches the possible applications. Here, we present a soft self-assembly of polyhedral Au colloids as a promising method to achieve unnaturally high n values. The interfacial assembly of Au nanocubes provides n of 6.4 at the resonant wavelength (near-infrared) and 4.5 in the o?-resonant regimes (mid-infrared), which have not been previously reached. The soft self-assembly of polyhedral Au colloids can be a versatile and highly e?ective route for the fabrication of optical metamaterials with unnaturally high n values.
关键词： Metamaterials,Self-assembly,Plasmonic colloids,E?ective medium theory,Refractive index
更新于2025-09-19 17:13:59
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Au@Ag Corea??Shell Nanorods Support Plasmonic Fano Resonances
摘要： In this work, we investigated experimentally and theoretically the plasmonic Fano resonances (FRs) exhibited by core–shell nanorods composed of a gold core and a silver shell (Au@Ag NRs). The colloidal synthesis of these Au@Ag NRs produces nanostructures with rich plasmonic features, of which two different FRs are particularly interesting. The FR with spectral location at higher energies (3.7 eV) originates from the interaction between a plasmonic mode of the nanoparticle and the interband transitions of Au. In contrast, the tunable FR at lower energies (2.92–2.75 eV) is ascribed to the interaction between the dominant transversal LSPR mode of the Ag shell and the transversal plasmon mode of the Au@Ag nanostructure. The unique symmetrical morphology and FRs of these Au@Ag NRs make them promising candidates for plasmonic sensors and metamaterials components.
关键词： Au@Ag NRs,metamaterials,core–shell nanorods,plasmonic Fano resonances,plasmonic sensors
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Symposium on Phased Array System & Technology (PAST) - Waltham, MA, USA (2019.10.15-2019.10.18)] 2019 IEEE International Symposium on Phased Array System & Technology (PAST) - Demonstration of Metamaterial-Enabled Overlapped Subarray for a Linear Array
摘要： Known overlapped subarray antennas combine array elements in a complex corporate or space-fed beamforming network, resulting in reduced scan loss and grating lobes. In this paper we demonstrate an overlapped subarray antenna enabled simply by a low index metamaterial lens (metalens) over a 5 horn line array. The metalens was designed to spread the field from the horn element with an aperture field distribution that generates an element pattern with flat top and low sidelobes. The paper presents the analytical technique used in the lens design, shows predicted and measured patterns, and discusses challenges and opportunities for achieving wide bandwidth and full scan from a 2-dimensional aperture array with a metalens.
关键词： horn array,overlapped subarray,metamaterials,low index,metalens
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Real-world PV Module Degradation across Climate Zones Determined from Suns-V <sub/>oc</sub> , Loss Factors and I-V Steps Analysis of Eight Years of I-V, P <sub/>mp</sub> Time-series Datastreams
摘要： Planar distributed full-tensor anisotropic metamaterials for cloaks of invisibility based on transformation electromagnetics are proposed. The proposed metamaterials are composed of nonresonant transmission lines and are advantageous in full control of the off-diagonal components of the permeability tensor as well as broadband and low-loss characteristics. The explicit design formulas for the metamaterials are given based on the equivalent circuit derived directly from Maxwell's equations. A carpet cloak of invisibility is designed and the validity of the design theory is confirmed by circuit simulations. In addition, the carpet cloak is implemented in microstrip line technology and its performance is demonstrated experimentally at microwave frequencies.
关键词： Carpet cloaks of invisibility,transformation electromagnetics,metamaterials
更新于2025-09-19 17:13:59