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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - An Optimized Ultrathin and Broadband Metamaterial Absorber Using Slotted Square Loop with Multi Layers
摘要： An optimized ultrathin and broadband absorber is proposed in this paper. It is composed of a periodic array of slotted square loop-dielectric multilayered structure. The bottom layer consists of one dielectric with edge-overlapped slotted square metal loop on it. The simulated results indicate that the absorption at normal incidence is above 90% in almost the whole frequency range of 6.25-18GHz. Moreover, the designed absorber is ultrathin with a thickness of only 0.13-0.38 free-space wavelength at the lowest and highest frequencies, respectively.
关键词： broadband absorber,slotted square loop,Metamaterial,anti-reflection,multi-layer
更新于2025-09-23 15:22:29
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An Optically Transparent Broadband Microwave Absorber using Interdigital Capacitance
摘要： In this paper, an optically transparent broadband microwave absorber has been developed. The proposed geometry is constructed of patterned resistive films of ITO on flexible substrates, structure exhibits broadband absorptivity (above 90%) from 4 to 17.20 GHz (covering C, X, and Ku bands). The novelty of the design lies in leveraging the properties of interdigital capacitance to achieve wide absorption (fractional bandwidth of 124.53%), angular stability, as well as optical transparency compared to the earlier reported broadband absorbers. Moreover, the structure has been extensively investigated through deriving an equivalent circuit model and studying surface current distributions. Experimental validation of the fabricated prototype has also confirmed the potential use of resistive film based broadband absorbers in several applications.
关键词： interdigital capacitance,optically transparent absorber,Circuit analog absorber,broadband absorber
更新于2025-09-23 15:21:21
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Broadband light harvesting for highly efficient hot-electron application based on conformal metallic nanorod arrays
摘要： The utilization of nonradiative decay of surface plasmons (SPs) in the form of hot electrons in metallic nanostructures has a great potential for applications in photovoltaics, photocatalysis, photodetection, and surface imaging. Unfortunately, the metallic nanostructures usually support only narrowband plasmon resonances; moreover, the hot-electron thermalization loss during the transport to Schottky interface and the confined momentum space for hot-electron injection into semiconductor together result in an inefficient internal quantum process. In this study, we propose and experimentally demonstrate a broadband super absorber based on the metallic nanorod arrays (NRs). Optically, the average absorption across the entire visible band is up to 0.8, which is over 16-fold enhancement of the planar reference. Electrically, the hot electrons are controlled to be preferentially generated near Schottky interface within the mean free path, relieving the severe hot-electron thermalization loss. Moreover, the three-dimensional Schottky junction provides much increased hot-electron momentum space for injection at the vertical surface. These optical and electrical benefits lead to over 30-fold enhancement in the IPCE (incident photon-to-electron conversion efficiency) relative to the reference. The IPCE can be up to 10.9% at Eph = 3.1 eV, which is close to the limit of the thick-film single-barrier hot-electron devices. The conformal NRs system provides a promising strategy to simultaneously improve the hot-electron generation, transport and collection efficiencies and could be an outstanding candidate for efficient hot-electron optoelectronic and photocatalysis systems.
关键词： hot electron,surface plasmons,nanorod arrays,broadband absorber
更新于2025-09-23 15:21:21
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Ultraviolet to near infrared titanium nitride broadband plasmonic absorber
摘要： In this paper, we theoretically design and numerically verify a broadband plasmonic absorber that works continuously in ultraviolet to near-infrared region. Different from the traditional metal-insulator-metal (MIM) three-layer structure, our perfect absorber is based on insulator-metal-insulator-metal (IMIM) four-layer structure. This perfect absorber owns a 280 nm ultra-thin thickness, a configuration of refractory metal titanium nitride and high-melting-point insulator silica equips it with strong thermal stability. The novel titanium nitride ring-square array layer combines the absorption of different wavelength bands so that the absorber can achieves a continuous absorption of more than 90% from wavelength 200–1200 nm. Using Finite-difference time-domain (FDTD) method, we get a calculated average absorption rate as 94.85%, which includes a 99.40% maximum absorption at wavelength 270 nm and a 90.30% minimum absorption at 390 nm. In addition, this perfect absorber demonstrates polarization independence under normal incidence and large incident angle insensitivity under oblique incidence, which has significant application potentials in many areas such as solar energy collection, photothermal conversion, and invisibility cloak.
关键词： Broadband absorber,Ultraviolet to near infrared,Polarization independence,Plasmonic,Large incident angle insensitivity
更新于2025-09-19 17:13:59
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Broadband Near-Infrared Absorber Based on All Metallic Metasurface
摘要： Perfect broadband absorbers have increasingly been considered as important components for controllable thermal emission, energy harvesting, modulators, etc. However, perfect absorbers which can operate over a wide optical regime is still a big challenge to achieve. Here, we propose and numerically investigate a perfect broadband near-infrared absorber based on periodic array of four isosceles trapezoid prism (FITP) unit cell made of titanium (Ti) over a continuous silver film. The structure operates with low quality (Q) factor of the localized surface plasmon resonance (LSPR) because of the intrinsic high loss, which is the foundation of the broadband absorption. The high absorption of metal nanostructures mainly comes from the power loss caused by the continuous electron transition excited by the incident light inside the metal, and the resistance loss depends on the enhanced localized electric field caused by the FITP structure. Under normal incidence, the simulated absorption is over 90% in the spectrum ranging from 895 nm to 2269 nm. The absorber is polarization-independent at normal incidence, and has more than 80% high absorption persisting up to the incident angle of ~45° at TM polarization.
关键词： broadband absorber,near-infrared,localized surface plasmon resonance,metamaterial
更新于2025-09-12 10:27:22
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Polarization-Insensisitve Broadband Multi-layered Absorber Using Screen Printed Patterns of Resistive Ink
摘要： Design and implementation of a broadband polarization-insensitive multi-layered microwave absorber using resistive ink has been presented here. The proposed absorber is constructed using layers of resistive surface where each layer consists of periodic arrangement of resistive patterns printed on a low cost FR4 sheet using resistive ink. Due to the multilayered nature, the proposed absorber shows broadband absorption having simulated reflection co-efficient less than -10dB in the frequency range from 2.00 GHz to 18.50 GHz under normal incidence which covers the entire S, C, X and Ku bands with the smallest thickness of 0.082λL (at lowest operating frequency of the absorption band) as compared to the state-of the-art absorbers. In order to validate the proposed absorber, the equivalent circuit model has also been presented. The equivalent circuit model shows good match with the proposed absorber. The proposed absorber is experimentally verified and the experimental results shows good agreement with the simulated results.
关键词： Frequency selective surface,resistive ink,multi-layered absorber,Broadband absorber
更新于2025-09-11 14:15:04
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Broadband LWIR and MWIR absorber by trapezoid multilayered grating and SiO2 hybrid structures
摘要： A broadband metamaterial absorber with high absorption simultaneously in mid-wave infrared (MWIR) and long-wave infrared (LWIR) was proposed. In the MWIR, the absorption higher than 0.8 is from 4 to 6.3 μm, while the absorption in the LWIR is from 8.7 and 9.6 μm. The absorber is insensitive to the incident angle. The broadband absorption in the MWIR is due to the slow-light effect of the trapezoid multilayered grating structure. And the broadband absorption in the LWIR is due to the phonon polariton resonant of trapezoid SiO2 layer. In the broadband high absorption region, the atmosphere is transparent, which may greatly promote the practical application of the absorber in double-color IR imaging, detecting, infrared stealth and thermal emitting.
关键词： Metamaterial,Transparent atmosphere window,Broadband absorber,Slow-light effect,Phonon polariton resonant
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Graphene Based Absorber Using LTJEC FDTD
摘要： A terahertz absorber using graphene is simulated using Laplace transform current density convolution finite difference time domain method. An absorber with approximately unity absorption is designed with a graphene ribbon array and a graphene sheet. The numerical results are presented to validate the proposed structure and demonstrate that the graphene sheet is an appropriate material to develop a broadband absorber.
关键词： Graphene,Broadband absorber,Finite difference time domain method,Laplace transform
更新于2025-09-04 15:30:14
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Polarization-insensitive and wide-angle broadband absorption enhancement of molybdenum disulfide in visible regime
摘要： In order to remarkably enhance the absorption capability of monolayer molybdenum disulfide (MoS2), a broadband MoS2-based perfect absorber, which is inspired by metamaterial, is proposed. By using the finite-difference time-domain (FDTD) simulations, the absorption of proposed MoS2-based absorber above 94% is achieved from 594 to 809 nm. Meanwhile, the average absorptions of monolayer MoS2 enhanced up to 27% and 67% are realized from 598 to 671 nm and 710 to 801 nm, respectively. By manipulating related structural parameters, the absorption spectrum can be further broadened and shifted in a wide wavelength range. Furthermore, the proposed absorber can tolerate a relatively wide range of incident angles and demonstrate polarization-independence.
关键词： metamaterial,polarization-insensitive,wide-angle,broadband absorber,MoS2
更新于2025-09-04 15:30:14