Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

Article Types

Countries / Regions

Search Results (15)

Search Parameters:
Keywords = ultra-wideband optical absorber

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
17 pages, 3338 KiB  
Article
Multimode Switching Broadband Terahertz Metamaterial Absorbing Micro-Devices Based on Graphene and Vanadium Oxide
by Xin Ning, Qianju Song, Zao Yi, Jianguo Zhang and Yougen Yi
Nanomaterials 2025, 15(11), 867; https://doi.org/10.3390/nano15110867 - 4 Jun 2025
Viewed by 431
Abstract
In this paper, we propose a multi-mode switchable ultra-wideband terahertz absorber based on patterned graphene and VO2 by designing a graphene pattern composed of a large rectangle rotated 45° in the center and four identical small rectangles in the periphery, as well [...] Read more.
In this paper, we propose a multi-mode switchable ultra-wideband terahertz absorber based on patterned graphene and VO2 by designing a graphene pattern composed of a large rectangle rotated 45° in the center and four identical small rectangles in the periphery, as well as a VO2 layer pattern composed of four identical rectangular boxes and small rectangles embedded in the dielectric layer. VO2 can regulate conductivity via temperature, the Fermi level of graphene depends on the external voltage, and the graphene layer and VO2 layer produce resonance responses at different frequencies, resulting in high absorption. The proposed absorption microdevices have three modes: Mode 1 (2.52–4.52 THz), Mode 2 (3.91–9.66 THz), and Mode 3 (2.14–10 THz), which are low-band absorption, high-band absorption, and ultra-wideband absorption. At 2.96 THz in Mode 1, the absorption rate reaches 99.98%; at 8.04 THz in Mode 2, the absorption rate reaches 99.76%; at 5.04 THz in Mode 3, the absorption rate reaches 99.85%; and at 8.4 THz, the absorption rate reaches 99.76%. We explain the absorption mechanism by analyzing the electric field distribution and local plasma resonance, and reveal the high-performance absorption mechanism by using the relative impedance theory. In addition, absorption microdevices have the advantages of polarization insensitivity, incident angle insensitivity, multi-mode switching, ultra-wideband absorption, large manufacturing tolerance, etc., and have potential research and application value in electromagnetic stealth devices, filters and optical switches. Full article
Show Figures

Figure 1

17 pages, 6781 KiB  
Article
A Transparent and Flexible Absorber for Electromagnetic Interference Suppression, Designed for 5G Communication and Sub-6G Applications
by Senfeng Lai, Huiyuan Fu, Junxian Tan, Jingyi Luo and Bingye Zhou
Electronics 2025, 14(7), 1350; https://doi.org/10.3390/electronics14071350 - 28 Mar 2025
Viewed by 832
Abstract
As 5G technology rapidly advances, the extension of spectrum into millimeter-wave bands enables higher data speeds and reduced latency. However, this frequency expansion introduces significant electromagnetic interference (EMI) issues, particularly in environments with dense equipment and base stations. To tackle these challenges, this [...] Read more.
As 5G technology rapidly advances, the extension of spectrum into millimeter-wave bands enables higher data speeds and reduced latency. However, this frequency expansion introduces significant electromagnetic interference (EMI) issues, particularly in environments with dense equipment and base stations. To tackle these challenges, this paper presents a multilayer transparent ultra-wideband microwave absorber (MA) using indium tin oxide (ITO) that operates between 4 and 26 GHz. This optimized MA design successfully achieves absorption from 4.07 to 25.07 GHz, encompassing both the 5G Sub-6 GHz and n258 bands, with a relative bandwidth of 144% and a minimal thickness of 0.129λL (where λL is the free-space wavelength at the lowest cutoff frequency). For TE and TM polarization with incidence angles ranging from 0° to 45°, the MA demonstrates exceptional performance, maintaining a relative bandwidth exceeding 120%. Notably, for TM polarization with incidence angles between 60° and 70°, the MA can sustain an absorption capacity with a relative bandwidth greater than 100%. By integrating the principles of impedance matching, surface current theory, and equivalent circuit simulation fitting, the absorption mechanism is further analyzed, thereby confirming the reliability of the design. This design offers exceptional wideband absorption, optical transparency, and wide-angle incidence characteristics, demonstrating great potential for applications in electromagnetic stealth, EMI suppression, and electromagnetic compatibility (EMC) in 5G communications. Full article
Show Figures

Figure 1

17 pages, 5934 KiB  
Article
Investigation of an Ultra-Wideband Optical Absorber with the Bandwidth from Ultraviolet C to Middle Infrared
by Chih-Ching Hung, Xin-Yu Lin, Tung-Lung Wu, Shu-Han Liao, Ho-Sheng Chen and Cheng-Fu Yang
Photonics 2025, 12(1), 83; https://doi.org/10.3390/photonics12010083 - 17 Jan 2025
Cited by 1 | Viewed by 993
Abstract
In the development of optical absorption technology, achieving ultra-wideband high absorption structures that span from the 200 nm ultraviolet C region to the 5800 nm mid-infrared range has been a significant challenge in materials science. Previous studies have shown that few optical absorbers [...] Read more.
In the development of optical absorption technology, achieving ultra-wideband high absorption structures that span from the 200 nm ultraviolet C region to the 5800 nm mid-infrared range has been a significant challenge in materials science. Previous studies have shown that few optical absorbers can simultaneously achieve an absorption rate above 0.900 and cover such a vast spectral range. This study presents an innovative seven-layer composite structure that successfully addresses this long-standing technical issue. Through a carefully designed layered architecture, the researchers employed COMSOL Multiphysics (version 6.0) for detailed numerical simulations to verify the optical performance of the structure. The structural design features two key innovations. In the layered composition, the bottom (h1), h3, and h5 layers are made of metallic Fe, while the layers above them (h2, h4, and h6) use SiO2. The top layer is composed of a discontinuous cylinder Ti matrix. The first innovation involves the use of an inwardly recessed square design on the metallic Fe planes of the h4 and h6 layers, achieving high absorption across the 600–5800 nm range. The second innovation involves the use of the discontinuous cylinder Ti matrix for the top layer, which successfully enhances absorption performance in the 200–600 nm wavelength range. This structure not only employs relatively low-cost metals and oxide materials but also demonstrates significant optical absorption potential. Through numerical simulations and precise structural design, this study provides new ideas and technological pathways for the development of ultra-wideband optical absorbers. Full article
(This article belongs to the Special Issue Optical Metamaterials for Advanced Optoelectronic Devices)
Show Figures

Figure 1

16 pages, 6623 KiB  
Article
An Ultra-Wideband Metamaterial Absorber Ranging from Near-Infrared to Mid-Infrared
by Jing-Jenn Lin, Dun-Yu Huang, Meng-Long Hong, Jo-Ling Huang, Chih-Hsuan Wang, Cheng-Fu Yang and Kuei-Kuei Lai
Photonics 2024, 11(10), 939; https://doi.org/10.3390/photonics11100939 - 6 Oct 2024
Cited by 2 | Viewed by 1112
Abstract
This study focused on designing an ultra-wideband metamaterial absorber, consisting of layers of Mn (manganese) and MoO3 (molybdenum trioxide) arranged in a planar interleaving pattern, with a matrix square-shaped Ti (titanium) on the top MoO3 layer. Key features of this research [...] Read more.
This study focused on designing an ultra-wideband metamaterial absorber, consisting of layers of Mn (manganese) and MoO3 (molybdenum trioxide) arranged in a planar interleaving pattern, with a matrix square-shaped Ti (titanium) on the top MoO3 layer. Key features of this research included the novel use of Mn and MoO3 in a planar interleaving configuration for designing an ultra-wideband absorber, which was rarely explored in previous studies. MoO3 thin film served as the fundamental material, leveraging its favorable optical properties and absorption capabilities in the infrared spectrum. Alternating layers of Mn and MoO3 were adjusted in thickness and order to optimize absorptivity across desired wavelength ranges. Another feature is that the Mn and MoO3 materials in the investigated absorber had a planar structure, which simplified the manufacturing of the absorber. Furthermore, the topmost layer of square-shaped Ti was strategically placed to enhance the absorber’s bandwidth and efficiency. When the investigated absorber lacked a Ti layer, its absorptivity and bandwidth significantly decreased. This structural design leveraged the optical properties of Mn, MoO3, and Ti to significantly expand the absorption range across an ultra-wideband spectrum. When the Ti height was 280 nm, the investigated absorber exhibited a bandwidth with absorptivity greater than 0.9, spanning from the near-infrared (0.80 μm) to the mid-infrared (9.07 μm). The average absorptivity in this range was 0.950 with a maximum absorptivity of 0.989. Additionally, three absorption peaks were observed at 1010, 2510, and 6580 nm. This broad absorption capability makes it suitable for a variety of optical applications, ranging from near-infrared to mid-infrared wavelengths, including thermal imaging and optical sensing. Full article
(This article belongs to the Special Issue Emerging Trends in Metamaterials and Metasurfaces Research)
Show Figures

Figure 1

18 pages, 8359 KiB  
Article
Analyses of an Ultra-Wideband Absorber from UV-B to Middle-IR Utilizing a Square Nanopillar and a Square Hollow Embedded in a Square Cavity of the Top Layer of Multilayer Metamaterials
by Chia-Te Liao, Pei-Xiu Ke, Chia-Min Ho, Cheng-Fu Yang and Tung-Lung Wu
Photonics 2024, 11(8), 742; https://doi.org/10.3390/photonics11080742 - 8 Aug 2024
Cited by 1 | Viewed by 1144
Abstract
In this study, an ultra-wideband absorber spanning from UV-B to middle-IR was designed and analyzed using a novel structure. The multilayer metamaterial, arranged from bottom to top, consisted of an Al metal layer, a lower SiO2 layer, a graphite layer, another SiO [...] Read more.
In this study, an ultra-wideband absorber spanning from UV-B to middle-IR was designed and analyzed using a novel structure. The multilayer metamaterial, arranged from bottom to top, consisted of an Al metal layer, a lower SiO2 layer, a graphite layer, another SiO2 layer, a thin Ti layer, and a top SiO2 layer. The top layer of SiO2 had a 200 nm square cavity etched out, and then a square Ti nanopillar and a square Ti hollow outside a Ti nanopillar were embedded. This specific arrangement was chosen to maximize the absorption properties across a broad spectrum. The absorption spectrum of the designed absorber was thoroughly analyzed using the commercial finite element analysis software COMSOL Multiphysics® (version 6.0). This analysis confirmed that the combination of these various components achieved perfect absorption and an ultra-wideband response. The synergistic interaction between the layers and the nanopillars structure contributed significantly to the absorber’s efficiency, making it a promising candidate for applications requiring broad-spectrum absorption. The comprehensive analyses of the parameters for different structures demonstrated that the effects of guided-mode resonance, coupling resonance, optical impedance matching, and propagating surface plasmon resonance existed in the investigated structure. The optimal model, determined through analyses using COMSOL Multiphysics®, showed that the broadband absorption in the range of 270 to 3600 nm, spanning from UV-B to middle-IR, exceeded 90.0%. The average absorption rate within this range was 0.967, with the highest reaching a near-perfect absorptivity of 99.9%. We also compared three absorption spectra in this study: the t1–t6 flat structure, the t1–t5 flat structure with t6 featuring a square cavity, and the structure proposed in this study. This demonstrates that a square nanopillar and a square hollow embedded in a square cavity can enhance the absorptive properties of the absorber. Full article
(This article belongs to the Special Issue Emerging Trends in Metamaterials and Metasurfaces Research)
Show Figures

Figure 1

11 pages, 7143 KiB  
Article
A Broadband Meta-Absorber for Curved Terahertz Stealth Applications
by Saima Hafeez, Jianguo Yu, Fahim Aziz Umrani, Abdul Majeed and Wang Yun
Electronics 2024, 13(15), 2966; https://doi.org/10.3390/electronics13152966 - 27 Jul 2024
Cited by 3 | Viewed by 1402
Abstract
Metasurface absorbers have shown significant potential in stealth applications due to their adaptability and capacity to reduce the backscattering of electromagnetic (EM) waves. Nevertheless, due to the materials used in the terahertz (THz) range, simultaneously achieving excellent stealth performance in ultrawideband remains an [...] Read more.
Metasurface absorbers have shown significant potential in stealth applications due to their adaptability and capacity to reduce the backscattering of electromagnetic (EM) waves. Nevertheless, due to the materials used in the terahertz (THz) range, simultaneously achieving excellent stealth performance in ultrawideband remains an important and difficult challenge to overcome. In this study, an ultrawideband absorber is proposed based on indium tin oxide (ITO) and polyethylene-terephthalate (PET), with a structure thickness of only 0.16λ. ITO sheets are utilized to achieve broad-spectrum, optical transparency and flexibility of the metasurface. The results show that absorption higher than 90% can be achieved in the frequency band ranging from 1.75 to 5 THz under normal TE and TM polarizations, which covers a wide THz band. The structure is insensitive to polarization angles and exhibits 97% relative bandwidth above 90% efficiency up to an oblique incident angle of 60°. To further validate the efficiency of the absorption performance, the radar cross-section (RCS) reduction investigation was performed on both planar and conformal configurations. The findings show that under normal incidence EM waves, both flat and curved surfaces can achieve RCS reduction of over 10 dB, covering an extremely wide frequency range of 1.75 to 5 THz. The metasurface presented in this study exhibits significant potential for use in several THz applications, including flexible electronic devices and stealth aircraft windows. Full article
(This article belongs to the Section Microwave and Wireless Communications)
Show Figures

Figure 1

18 pages, 4684 KiB  
Article
Development and Fabrication of a Multi-Layer Planar Solar Light Absorber Achieving High Absorptivity and Ultra-Wideband Response from Visible Light to Infrared
by Cheng-Fu Yang, Chih-Hsuan Wang, Pei-Xiu Ke, Teen-Hang Meen and Kuei-Kuei Lai
Nanomaterials 2024, 14(11), 930; https://doi.org/10.3390/nano14110930 - 25 May 2024
Cited by 2 | Viewed by 1368
Abstract
The objective of this study is to create a planar solar light absorber that exhibits exceptional absorption characteristics spanning from visible light to infrared across an ultra-wide spectral range. The eight layered structures of the absorber, from top to bottom, consisted of Al [...] Read more.
The objective of this study is to create a planar solar light absorber that exhibits exceptional absorption characteristics spanning from visible light to infrared across an ultra-wide spectral range. The eight layered structures of the absorber, from top to bottom, consisted of Al2O3, Ti, Al2O3, Ti, Al2O3, Ni, Al2O3, and Al. The COMSOL Multiphysics® simulation software (version 6.0) was utilized to construct the absorber model and perform simulation analyses. The first significant finding of this study is that as compared to absorbers featuring seven-layered structures (excluding the top Al2O3 layer) or using TiO2 or SiO2 layers as substituted for Al2O3 layer, the presence of the top Al2O3 layer demonstrated superior anti-reflection properties. Another noteworthy finding was that the top Al2O3 layer provided better impedance matching compared to scenarios where it was absent or replaced with TiO2 or SiO2 layers, enhancing the absorber’s overall efficiency. Consequently, across the ultra-wideband spectrum spanning 350 to 1970 nm, the average absorptivity reached an impressive 96.76%. One significant novelty of this study was the utilization of various top-layer materials to assess the absorption and reflection spectra, along with the optical-impedance-matching properties of the designed absorber. Another notable contribution was the successful implementation of evaporation techniques for depositing and manufacturing this optimized absorber. A further innovation involved the use of transmission electron microscopy to observe the thickness of each deposition layer. Subsequently, the simulated and calculated absorption spectra of solar energy across the AM1.5 spectrum for both the designed and fabricated absorbers were compared, demonstrating a match between the measured and simulated results. Full article
Show Figures

Figure 1

18 pages, 4768 KiB  
Article
Investigation of a Pyramid-like Optical Absorber with High Absorptivity in the Range of Ultraviolet A to Middle Infrared
by Qinyin Chen, Jo-Ling Huang, Chih-Hsuan Wang, Pei-Xiu Ke, Cheng-Fu Yang and Hsien-Wei Tseng
Photonics 2024, 11(4), 352; https://doi.org/10.3390/photonics11040352 - 10 Apr 2024
Viewed by 1275
Abstract
In this study, a simple pyramid-like ultra-wideband absorber was designed to explore high absorptivity across a wide bandwidth. The absorber consisted of eight layers organized into four groups, and each group comprised a metal layer followed by an oxide layer, both of which [...] Read more.
In this study, a simple pyramid-like ultra-wideband absorber was designed to explore high absorptivity across a wide bandwidth. The absorber consisted of eight layers organized into four groups, and each group comprised a metal layer followed by an oxide layer, both of which were square with equal side lengths. Specifically, the chosen oxides, arranged from bottom to top, included SiO2 (t7 layer), Al2O3 (t5 layer), SiO2 (t3 layer), and Al2O3 (t1 layer). In the initial design phase, the thickness of the t8 Ti layer was set to 50 nm and assigned initial values to the thicknesses of the t7-t1 layers, and the widths of the four groups w4, w3, w2, and w1, decreased successively from bottom to top, creating a structure reminiscent of a pyramid. Comsol (version 6.0) was utilized to simulate and systematically vary one parameter at a time, ranging from the thicknesses of the t7-t1 layers to the widths of w4-w1, in order to identify the most suitable structural parameters. Our analyses demonstrated that multimode resonance arose due to the emergence of absorption peaks at lower wavelengths between larger and smaller areas. Additionally, surface plasmon resonance and interference effects between various layers and materials were attributed to the alternating arrangement of metal and oxide layers. The enhancements in the electric field observed at different resonance peak wavelengths illustrated the Fabry–Perot cavity effect, while the impedance matching effect was observed through variations in the real and imaginary parts of the optical impedance with respect to the wave vector. After simulating using these optimally found thicknesses and widths, the aforementioned effects manifested in the pyramid-like ultra-wideband absorber we designed, with its absorptivity surpassing 0.900 across the spectrum from ultraviolet A (335 nm) to middle infrared (4865 nm). Full article
(This article belongs to the Special Issue New Insights into Optical Materials)
Show Figures

Figure 1

18 pages, 5948 KiB  
Article
Using Planar Metamaterials to Design a Bidirectional Switching Functionality Absorber—An Ultra-Wideband Optical Absorber and Multi-Wavelength Resonant Absorber
by Shu-Han Liao, Chih-Hsuan Wang, Pei-Xiu Ke and Cheng-Fu Yang
Photonics 2024, 11(3), 199; https://doi.org/10.3390/photonics11030199 - 23 Feb 2024
Cited by 3 | Viewed by 1628
Abstract
This study aimed to investigate a bidirectional switching functionality absorber, which exhibited an ultra-wideband characteristic in one direction, while in the other direction it demonstrated the absorption of three different resonant wavelengths (frequencies). The fully layered planar structure of the absorber consisted of [...] Read more.
This study aimed to investigate a bidirectional switching functionality absorber, which exhibited an ultra-wideband characteristic in one direction, while in the other direction it demonstrated the absorption of three different resonant wavelengths (frequencies). The fully layered planar structure of the absorber consisted of Al2O3, Zr, yttria-stabilized zirconia (YSZ), Zr, YSZ, Al, YSZ, and Al. The simulations were conducted using the COMSOL Multiphysics® simulation software (version 6.1) for analyses, and this study introduced three pivotal innovations. Firstly, there had been scarce exploration of YSZ and Zr as the materials for designing absorbers. The uses of YSZ and Zr in this context were a relatively uncharted territory, and our research endeavored to showcase their distinctive performance as absorber materials. Secondly, the development of a planar absorber with multifunctional characteristics was a rarity in the existing literature. This encompassed the integrations of an ultra-wideband optical absorber and the creation of a multi-wavelength resonant absorber featuring three resonant wavelengths. The design of such a multi-wavelength resonant absorber holds promise for diverse applications in optical detection and communication systems, presenting novel possibilities in related fields. Lastly, a notable discovery was demonstrated: a discernible redshift phenomenon in the wavelengths of the three resonant peaks when the thickness of YSZ, serving as the material of resonant absorber layer, was increased. Full article
Show Figures

Figure 1

20 pages, 5588 KiB  
Article
Analysis of an Ultra-Wideband, Perfectly Absorptive Fractal Absorber with a Central Square Nanopillar in a Cylindrical Structure with a Square Hollow
by Shang-Te Tsai, Jo-Ling Huang, Pei-Xiu Ke, Cheng-Fu Yang and Hung-Cheng Chen
Materials 2023, 16(21), 6898; https://doi.org/10.3390/ma16216898 - 27 Oct 2023
Cited by 4 | Viewed by 1413
Abstract
In this study, a fractal absorber was designed to enhance light absorptivity and improve the efficiency of converting solar energy into electricity for a range of solar energy technologies. The absorber consisted of multiple layers arranged from bottom to top, and the bottom [...] Read more.
In this study, a fractal absorber was designed to enhance light absorptivity and improve the efficiency of converting solar energy into electricity for a range of solar energy technologies. The absorber consisted of multiple layers arranged from bottom to top, and the bottom layer was made of Ti metal, followed by a thin layer of MgF2 atop it. Above the two layers, a structure comprising square pillars formed by three layers of Ti/MgF2/Ti was formed. This pillar was encompassed by a square hollow with cylindrical structures made of Ti material on the exterior. The software utilized for this study was COMSOL Multiphysics® (version 6.0). This study contains an absorption spectrum analysis of the various components of the designed absorber system, confirming the notion that achieving ultra-wideband and perfect absorption resulted from the combination of the various components. A comprehensive analysis was also conducted on the width of the central square pillar, and the analysis results demonstrate the presence of several remarkable optical phenomena within the investigated structure, including propagating surface plasmon resonance, localized surface plasmon resonance, Fabry–Perot cavity resonance, and symmetric coupling plasma modes. The optimal model determined through this software demonstrated that broadband absorption in the range of 276 to 2668 nm, which was in the range of UV-B to near-infrared, exceeded 90.0%. The average absorption rate in the range of 276~2668 nm reached 0.965, with the highest achieving a perfect absorptivity of 99.9%. A comparison between absorption with and without outer cylindrical structures revealed that the resonance effects significantly enhanced absorption efficiency, as evidenced by a comparison of electric field distributions. Full article
Show Figures

Figure 1

13 pages, 3602 KiB  
Article
Design of an Ultra-Wideband Transparent Wave Absorber
by Huijuan Dai, Shuying Li, Peng Dong and Yanqin Ma
Materials 2023, 16(17), 5962; https://doi.org/10.3390/ma16175962 - 31 Aug 2023
Cited by 8 | Viewed by 1923
Abstract
In this paper, a multilayer ultra-wideband transparent metamaterial wave absorber is proposed, which has the characteristics of ultra-wideband wave absorption, light transmission and flexible bending; in addition, due to the complete symmetry of the structure, the absorber has polarization insensitivity to incident electromagnetic [...] Read more.
In this paper, a multilayer ultra-wideband transparent metamaterial wave absorber is proposed, which has the characteristics of ultra-wideband wave absorption, light transmission and flexible bending; in addition, due to the complete symmetry of the structure, the absorber has polarization insensitivity to incident electromagnetic waves. Both simulation and experimental results show that the frequency range of the microwave absorption rate is higher than 90% between 8.7 GHz and 38.9 GHz (between which most of the absorption rate can reach more than 95%), the total bandwidth is 30.2 GHz, and the relative bandwidth is 126.9%, realizing microwave broadband absorption and covering commonly used communication frequency bands such as X-band, Ku-band, and K-band. A sample was processed and tested. The test results are in good agreement with the results of the theoretical analysis, which proves the correctness of the theoretical analysis. In addition, through the selection and oxidation of indium tin (ITO) materials, the metamaterial also has the characteristics of optical transparency and flexibility, so it has potential application value in the window radar stealth and conformal radar stealth of weapons and equipment. Full article
Show Figures

Figure 1

12 pages, 3763 KiB  
Article
Design and Numerical Analysis of Ultra-Broadband Absorber with Chimney Type Structure
by Yongchang Wu, Yue Liu, Wenzhuang Ma, Yushan Chen, Yuyao Cheng, Degui Li, Jing Liu and Yu Gu
Photonics 2023, 10(7), 742; https://doi.org/10.3390/photonics10070742 - 28 Jun 2023
Cited by 4 | Viewed by 1513
Abstract
In this study, a novel ultra-broadband absorber is suggested and numerically analyzed to demonstrate that the suggested absorber can achieve an average absorbance of 98.6% in the visible to near-infrared wavelength range (496–2100 nm). The structure of the proposed new ultra-wideband absorber consists [...] Read more.
In this study, a novel ultra-broadband absorber is suggested and numerically analyzed to demonstrate that the suggested absorber can achieve an average absorbance of 98.6% in the visible to near-infrared wavelength range (496–2100 nm). The structure of the proposed new ultra-wideband absorber consists of four thin films of silicon dioxide (SiO2), iron (Fe), magnesium fluoride (MgF2), and chromium (Cr). We have examined the structure’s electromagnetic field intensity distribution at numerous selected optical wavelengths and the influence of various structural parameters on the absorption performance of the absorber to offer a physical mechanism underlying the ultra-broadband absorption effect. Furthermore, in the presence of high-performance absorption, the structure has the effect of stabilizing absorption at large angles of incidence and is polarization-independent at vertical angles of incidence. The study also assesses the solar absorption capability of this structure, indicating that the structure has potential applications in solar absorption, such as solar energy collection and conversion, solar power generation, and thermal emitters. Full article
Show Figures

Figure 1

14 pages, 6332 KiB  
Article
A Theoretical Proposal for an Actively Controlled Ultra-Wideband Absorber Based on Vanadium Dioxide Hybrid Metamaterials
by Ubaid Ur Rahman Qureshi, Muhammad Ismail Khan and Bin Hu
Appl. Sci. 2022, 12(19), 10164; https://doi.org/10.3390/app121910164 - 10 Oct 2022
Cited by 17 | Viewed by 2313
Abstract
In this study, an ultra-wideband actively tunable terahertz absorber composed of four identical arc-shaped structures made of phase transition material vanadium dioxide (VO2) is presented. A metal ground plane is placed at the bottom and an insulating spacer (quartz) as the [...] Read more.
In this study, an ultra-wideband actively tunable terahertz absorber composed of four identical arc-shaped structures made of phase transition material vanadium dioxide (VO2) is presented. A metal ground plane is placed at the bottom and an insulating spacer (quartz) as the middle dielectric layer. Simulation results demonstrate 90% absorption with a broad bandwidth spanning 3 THz (2.7 THz–5.7 THz) under normal incidence. The proposed structure transforms from a reflector to an absorber by changing the conductivity from 200 S/m to 2 × 105 S/m; the absorbance at peak frequencies can be consistently tuned from 4% to 100%. Absorption spectra demonstrate that the polarization angle does not affect the response of the proposed structure. Power loss density (PLD) and impedance-matching theory are further analyzed to learn more about the physical origin of ultra-wide absorption. The ultra-wide operating bandwidth, high absorption efficiency, active tunability, and independence of polarization make the proposed structure an excellent candidate for integration into profound THz applications such as sensors, modulators, and optic-electro switches. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
Show Figures

Figure 1

14 pages, 5447 KiB  
Article
Ultrawideband Polarization-Independent Nanoarchitectonics: A Perfect Metamaterial Absorber for Visible and Infrared Optical Window Applications
by Mohammad Lutful Hakim, Abu Hanif, Touhidul Alam, Mohammad Tariqul Islam, Haslina Arshad, Mohamed S. Soliman, Saleh Mohammad Albadran and Md. Shabiul Islam
Nanomaterials 2022, 12(16), 2849; https://doi.org/10.3390/nano12162849 - 18 Aug 2022
Cited by 36 | Viewed by 3249
Abstract
This article presents numerical analysis of an ultrathin concentric hexagonal ring resonator (CHRR) metamaterial absorber (MMA) for ultrawideband visible and infrared optical window applications. The proposed MMA exhibits an absorption of above 90% from 380 to 2500 nm and an average absorbance of [...] Read more.
This article presents numerical analysis of an ultrathin concentric hexagonal ring resonator (CHRR) metamaterial absorber (MMA) for ultrawideband visible and infrared optical window applications. The proposed MMA exhibits an absorption of above 90% from 380 to 2500 nm and an average absorbance of 96.64% at entire operational bandwidth with a compact unit cell size of 66 × 66 nm2. The designed MMA shows maximum absorption of 99% at 618 nm. The absorption bandwidth of the MMA covers the entire visible and infrared optical windows. The nickel material has been used to design the top and bottom layer of MMA, where aluminium nitride (AlN) has been used as the substrate. The designed hexagonal MMA shows polarization-independent properties due to the symmetry of the design and a stable absorption label is also achieved for oblique incident angles up to 70 °C. The absorption property of hexagonal ring resonator MMA has been analyzed by design evaluation, parametric and various material investigations. The metamaterial property, surface current allocation, magnetic field and electric field have also been analyzed to explore the absorption properties. The proposed MMA has promising prospects in numerous applications like infrared detection, solar cells, gas detection sensors, imaging, etc. Full article
Show Figures

Figure 1

14 pages, 5211 KiB  
Article
Wide-Oblique-Incident-Angle Stable Polarization-Insensitive Ultra-Wideband Metamaterial Perfect Absorber for Visible Optical Wavelength Applications
by Mohammad Lutful Hakim, Touhidul Alam, Md. Shabiul Islam, M. Salaheldeen M., Sami H. A. Almalki, Mohd Hafiz Baharuddin, Haitham Alsaif and Mohammad Tariqul Islam
Materials 2022, 15(6), 2201; https://doi.org/10.3390/ma15062201 - 16 Mar 2022
Cited by 32 | Viewed by 3832
Abstract
Metamaterial absorbers are very attractive due to their significant absorption behavior at optical wavelengths, which can be implemented for energy harvesting, plasmonic sensors, imaging, optical modulators, photovoltaic detectors, etc. This paper presents a numerical study of an ultra-wide-band double square ring (DSR) metamaterial [...] Read more.
Metamaterial absorbers are very attractive due to their significant absorption behavior at optical wavelengths, which can be implemented for energy harvesting, plasmonic sensors, imaging, optical modulators, photovoltaic detectors, etc. This paper presents a numerical study of an ultra-wide-band double square ring (DSR) metamaterial absorber (MMA) for the complete visible optical wavelength region, which is designed with a three-layer (tungsten-silicon dioxide-tungsten) substrate material. Due to the symmetricity, a polarization-insensitive absorption is obtained for both transverse electric (TE) and transverse magnetic (TM) modes by simulation. An absorption above 92.2% and an average absorption of 97% are achieved in the visible optical wavelength region. A peak absorption of 99.99% is achieved at 521.83 nm. A wide range of oblique incident angle stabilities is found for stable absorption properties. A similar absorption is found for different banding angles, which may occur due to external forces during the installation of the absorber. The absorption is calculated by the interference theory (IT) model, and the polarization conversion ratio (PCR) is also validated to verify the perfect MMA. The electric field and magnetic field of the structure analysis are performed to understand the absorption property of the MMA. The presented MMA may be used in various applications such as solar cells, light detection, the biomedical field, sensors, and imaging. Full article
Show Figures

Graphical abstract

Back to TopTop