- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A Bi-layered Chiral Metamaterial with High-Performance Broadband Asymmetric Transmission of Linearly Polarized Wave
摘要： In this paper, a novel bi-layered chiral metamaterial (CMM) is presented to realize high–efficiency broadband asymmetric transmission (AT) of linearly polarized electromagnetic wave (EM) in the microwave region from 10.1GHz to 15.1GHz. For this purpose, a pair of modified resonators is employed on two sides of a thin dielectric substrate. The simulated and measured results confirm that linearly polarized wave in the form of x-polarized or y-polarized could be nearly converted into the orthogonal polarization after transmission through the introduced prototype which is affirmed by the polarization rotation azimuth angle . The polarization conversion ratio (PCR) is more than 92% at the mentioned frequency range. Full parametric simulation of modified resonators, azimuth rotation angle, and chirality parameter variable with frequency are discussed in detail. In addition, the surface current distributions of the structure have been demonstrated to investigate the physical mechanism of the cross-polarization and corresponding polarization conversion.
关键词： Metamaterials,chiral metamaterial,linearly polarized wave,asymmetric transmission
更新于2025-09-23 15:21:01
-
Polarizability of Radially Inhomogeneous Subwavelength Spheres
摘要： In this work the polarizability of a subwavelength core-shell sphere is considered, where the shell exhibits a radially inhomogeneous permittivity profile. The mathematical treatment of the electrostatic polarizability is formulated in terms of the scattering potentials and the corresponding scattering amplitudes. As a result, a generalized expression of the polarizability is presented to be dependent of the radial inhomogeneity function. The extracted general model is applied for two particular cases, i.e., a power-law profile and a new class of permittivity profiles that exhibit exponential radial dependence. The proposed analysis quantifies in a simple manner the inhomogeneity effects, allowing the direct implementation of naturally or artificially occurring permittivity inhomogeneities for a wide range of applications within and beyond the metamaterial paradigm. Specifically, a special case of symmetric-antisymmetric resonant plasmonic degeneracy is identified and shown for the case of a core-shell sphere with a power-law permittivity profile. This degeneracy could be used for the experimental identification of inhomogeneity-induced effects or for applications where a strong coupling resonant regime is required. Furthermore, the described analysis opens avenues towards the phenomenological and first-principles modeling of the electrodynamic scattering effects for graded-index plasmonic particles at the nanoscale. Finally, such a description can be readily used either for the benchmarking of novel computational methods incorporating inhomogeneous materials or for inverse scattering purposes.
关键词： inverse scattering,subwavelength,core-shell sphere,scattering potentials,metamaterial,exponential radial dependence,polarizability,scattering amplitudes,plasmonic degeneracy,radially inhomogeneous permittivity,power-law profile
更新于2025-09-23 15:21:01
-
A Stretchable Metamaterial Absorber with Deformation Compensation Design at Microwave Frequencies
摘要： A stretchable microwave metamaterial absorber with specific pattern design is proposed and fabricated in this paper to improve the stability of microwave absorption for deformation. Compensation mechanism is revealed by the electrical current loop for resonance absorption excitation in equivalent circuit model. The proposed metamaterial absorber with slotted cross pattern is compared with the conventional cross pattern absorber. A stretchable silver conductive ink validates the silk screen printing of resistive patterns on flexible polydimethylsiloxane (PDMS) substrate and hence realizes the stretching experiments. In a 25% stretch, the resonant frequency of the compensated absorber shifts only 0.5% for TM polarization, comparing to the 8% shifting of the conventional structure.
关键词： Stretchable,compensation mechanism,metamaterial absorber,resistive patterns,equivalent circuit model
更新于2025-09-23 15:21:01
-
The Optical Properties of Metamaterial-Superconductor Photonic Band Gap With/Without Defect Layer
摘要： In the present work, we have investigated theoretically the optical properties of a new one-dimensional defected photonic crystal structure (1DDPC). The structure is composed of alternating layers of metamaterial (double-negative material) and high Tc superconductor material called Hg1223 defected with a dielectric material (SiO2) at the center of the structure. The transmittance spectra of the proposed structure are obtained by using the transfer matrix method (TMM). We noticed that multiple transmittance peaks within the photonic band gap (PBG) as the thickness of defect layer increases. The tunable filtering feature is obtained by varying the thicknesses of metamaterial and superconductor layer. In addition, the defect peak is red shifted as well as photonic band gap tuned to low-frequency region. Our structure is sensitive to the variation of the angle incidence. Also, defect mode shown to be blue shifted as the angle of incidence increases. The tunable filtering properties are very useful in the optoelectronic applications.
关键词： Metamaterial,Photonic band gap,TMM,Superconductor
更新于2025-09-23 15:21:01
-
Fabrication of frequency selective metamaterial structure using low-cost laser writer
摘要： Tailoring the metamaterial structure using Laser writer lithography system offers a feasible way to accomplish the fine cross grating structures. The main focus of this work is to fabricate a metamaterial for absorption in the far infrared (far-IR) spectrum. Fabrication was carried out using homemade laser writer working at 405 nm in S1813 photoresist coated upon chromium on glass followed by its etching in the exposed regions. A 40 ? 40 array of unit cells with dimension in the order of 28 μm ? 1 μm were achieved. The structural characterization was carried out using scanning electron microscope (SEM) and Optical Microscope. We could observe clear absorption in the far-IR region. The results here would be favorable for the development of devices based on artificial material whose properties are not readily accessible in nature (metamaterials).
关键词： Optical microscope,FTIR,Laser writer,Metamaterial,SEM
更新于2025-09-23 15:19:57
-
Evaluation of performance of near-field thermophotovoltaic systems based on entropy analysis
摘要： Near-field radiative heat transfer can significantly improve the output power of thermophotovoltaic (TPV) systems. Therefore, it is crucial to explore how to increase the energy conversion efficiencies of near-field TPV systems. In this study, based on the fluctuation–dissipation theorem with the effective medium theory, we evaluate the performance of a near-field TPV system from the formulation of thermodynamics. It is found that a near-field TPV system consisting of InAs or GaSb cell can achieve higher heat flux or efficiency limit, respectively. Moreover, the TPV system with a hyperbolic metamaterial (HMM) emitter composed of nanowire or nanohole arrays can achieve higher heat flux and efficiency limit compared to that of the bulk reference. This is attributable to the HMMs being able to support hyperbolic modes, and the radiation with the HMM emitter exhibits a favorable entropy content for the energy conversion efficiency. This work provides an approach to determine the efficiency limit and establish a target for efficiency of the near-field TPV system without considering how the system works. The results of this study will facilitate the design and application of the HMM emitter and material of the TPV cell to improve the efficiency of near-field TPV systems.
关键词： Thermophotovoltaic systems,Near-field radiative heat transfer,Energy conversion efficiency,Hyperbolic metamaterial,Entropy analysis
更新于2025-09-23 15:19:57
-
A Broadband Tunable Terahertz Metamaterial Absorber Based on Single-Layer Complementary Gammadion-Shaped Graphene
摘要： We present a simple design of a broadband tunable metamaterial absorber (MMA) in the terahertz (THz) region, which consists of a single layer complementary gammadion-shaped (CGS) graphene sheet and a polydimethylsiloxane (PDMS) dielectric substrate placed on a continuous metal film. The Fermi energy level (Ef) of the graphene can be modulated dynamically by the applied DC bias voltage, which enables us to electrically control the absorption performance of the proposed MMA flexibly. When Ef = 0.8 eV, the relative bandwidth of the proposed MMA, which represents the frequency region of absorption beyond 90%, can reaches its maximal value of 72.1%. Simulated electric field distributions reveal that the broadband absorption mainly originates from the excitation of surface plasmon polaritons (SPPs) on the CGS graphene sheet. Furthermore, the proposed MMA is polarization-insensitive and has wide angles for both transverse-electric (TE) and transverse-magnetic (TM) waves in the broadband frequency range. The broadband absorption capacity of the designed MMA can be effectively adjusted by varying the Fermi energy level of graphene. Lastly, the absorbance of the MMA can be adjusted from 42% to 99.1% by changing the Ef from 0 eV to 0.8 eV, which is in agreement with the theoretical calculation by using the interference theory. Due to its simple structure and flexible tunability, the proposed MMA has potential application prospects in tunable filtering, modulators, sensing, and other multispectral devices.
关键词： graphene,surface plasmon polaritons,broadband tunable absorption,terahertz metamaterial absorber
更新于2025-09-23 15:19:57
-
Ultra-narrowband dielectric metamaterial absorber for sensing based on cavity-coupled phase resonance
摘要： We propose an ultra-narrowband dielectric metamaterial absorber with dielectric-dielectric-metal (DDM) structure where a dielectric cavity layer is inserted between the top compound periodic dielectric microstructures and bottom metal substrate. The results show that this absorber has an ultra-narrowband absorption with a full width at half-maximum (FWHM) of 0.028 nm and quality factor larger than 50,000 in the near-infrared regime. The electric field distribution shows that the phase resonance excited in the microstructures slits is coupled with the cavity resonance occurring in the middle dielectric layer which can greatly narrow the absorption bandwidth. More importantly, the absorption bandwidth can be flexibly manipulated by adjusting the thickness of the dielectric cavity layer. Due to the ultra-narrow absorption bandwidths and electric field concentrated in the slits, we can get a huge figure of merit (FOM) of 6731 which is much larger than those of the reported absorbers in the near-infrared regime. In addition, the larger FOM of 20,366 can be attained with higher-order mode resonance in the dielectric cavity layer. The proposed metamaterials have the great potentials in sensing applications.
关键词： Absorption,Sensor,Metamaterial,Absorber
更新于2025-09-23 15:19:57
-
A Tunable Terahertz Metamaterial Absorber Composed of Hourglass-Shaped Graphene Arrays
摘要： In this paper, we demonstrate a tunable periodic hourglass‐shaped graphene arrays absorber in the infrared (IR) and terahertz (THz) frequency bands. The effects of graphene geometric parameters, chemical potentials, periods, and incident angles on the pure absorption characteristics are studied by using the Finite Difference Time Domain (FDTD) method. In addition, this paper also analyzes the pure absorption characteristics of bilayer graphene arrays. The simulation results show that the maximum absorption reaches 38.2% for the monolayer graphene structure. Furthermore, comparing the bilayer graphene structure with the monolayer structure under the same conditions shows that the bilayer structure has a tunable dual‐band selective absorption effect and has a higher maximum absorption of 41.7%. Moreover, it was found that there are dual‐band tunable absorption peaks at 21.6 μm and 36.3 μm with the maximum absorption of 41.7% and 11%. The proposed structure is a convenient method which could be used in the design of graphene‐based optoelectronic devices, biosensors, and environmental monitors.
关键词： surface plasmon resonance,metamaterial absorber,graphene,finite difference time domain
更新于2025-09-23 15:19:57
-
[IEEE 2019 XVIII Workshop on Information Processing and Control (RPIC) - Bah?-a Blanca, Argentina (2019.9.18-2019.9.20)] 2019 XVIII Workshop on Information Processing and Control (RPIC) - Impact Produced by a Photovoltaic System on the Energy Utilization in an Educational Building
摘要： Enhancements of the directivity and front-to-back ratio (FTBR) of a metamaterial-inspired electrically small, linearly polarized, coaxially-fed Egyptian axe dipole antenna are considered. They are accomplished with a particular augmentation of the original near-field-resonant-parasitic (NFRP) antenna with an additional NFRP element, a small disc conductor modified with two meanderline-shaped slots. The entire system is evaluated numerically with two independent computational electromagnetics simulators. The optimized results demonstrate an electrically small antenna (i.e., ka < 1.0) with a reasonably low profile (i.e., height ～ λ/10) that improves the directivity from 1.77 to 6.32 dB, increases the FTBR from 0 to > 20 dB, and maintains large half-power beamwidths, while having a radiation efficiency over 80% with nearly complete matching to a 50 Ω source.
关键词： efficiency,Directivity,metamaterial-inspired antennas,front-to-back ratio,electrically small antennas,parasitic elements
更新于2025-09-23 15:19:57