Ultra-broadband Metamaterial Absorber Research Articles

An ultra broadband metamaterial absorber based on metal-dielectric-metal technology for THz spectrum

This paper introduces a novel ultra-broadband Metamaterial Absorber (UBMA) demonstrating significant absorption capabilities across a wide terahertz frequency range from 2.42 THz to 6.11 THz. The 3.7 THz bandwidth represents 87% of the central frequency. The proposed UBMA comprises three layers: a star-shaped metal patch on top, a dielectric substrate in the middle, and a metallic ground plane below. Simulations using CST Microwave Studio software reveal that the design achieves high absorption at five distinct frequencies: 2.47, 3.45, 4.89, 6.01, and 6.87 THz, with absorption rates of 99% for the first four peaks and 90% for the fifth peak. The study of electric field and surface current distribution provides insights into the absorption mechanism. While the UBMA exhibits polarization-independent performance, its angular response shows some sensitivity to the incident angle, especially beyond 30° Despite this, the absorber maintains over 70% absorptivity up to a 45° incidence angle for both TE and TM polarizations within specific frequency ranges. The simple structure combined with high absorption efficiency makes the UBMA suitable for THz imaging, detection, and stealth applications, although its angular sensitivity must be considered for certain applications.

Research on multi-resonance mechanism to achieve ultra-wideband high absorption of a metamaterial absorber in the UV to MIR range

Wideband metamaterial perfect absorbers have been extensively researched due to their excellent properties. A four-layer ultra-broadband metamaterial perfect absorber engraved with a square cavity is proposed. A clever combination of grating and square cavity allows the absorber to manifests an overall absorption of over 92 % and an average absorption rate of 97.27 % within the operational band from 280 to 5400 nm. Through analysis, it can be concluded that the coupling effects of Rayleigh anomaly (RA), magnetic resonance (MR), cavity resonance (CR), propagating surface plasmon resonance (PSPR) and local surface plasmon resonance (LSPR) result in perfect absorption. The absorber is insensitive to polarization and large angle incidence. It is worth mentioning that the average absorption rate of our structure reaches 93.32 % at a large incidence angle of 60° in TE mode, which is much higher than that of other absorbers. At 1000 K, the total photothermal conversion efficiency of our absorber is still above 90 %. The designed structure has the following advantages: high absorption, ultra-wide bandwidth, high tolerance to fabrication errors and insensitivity to large angle incidence. Thus, the absorber can be used in the solar energy harvesting and perfect stealth. Additionally, it also can be served as a reference in thermophotovoltaics, thermal imaging and infrared detection.

Metamaterial ultra-broadband absorber in near-infrared region with decreasing thermal emission

This study is aimed to present an ultra-broadband metamaterial absorber for infrared detection and thermal emitter applications. Despite numerous studies on metamaterial absorbers, achieving ultra-broadband absorption remains a challenge. We introduce a dual-gold square array with transverse magnetic polarization and combine it with an anti-reflective (GaAs) layer and metal-insulator (gold-Al2O3) configurations. The absorber achieves over 90 % absorption between 0.63 μm and 2.90 μm, with average and effective absorptions at 94.60 % and 94.68 %, respectively. Through impedance matching theory, we validate the performance of the absorber, analyze electric field distributions to explain its mechanism, and assess manufacturing tolerance for practical application viability. Our findings reveal robust performance of the metamaterial absorber across a wide spectral range, including insensitivity to incidence angles, with absorption over 80 % in 20–60°, highlighting its potential in the infrared detection and the thermal emitter.

Ultra-broadband metamaterial absorber for collecting electromagnetic waves from the ultraviolet to the mid-infrared

Due to the inherent local limitations of surface plasmon resonance, it is challenging to design an ultra-broadband electromagnetic wave absorber covering multiple bands. In this paper, a novel Ultra-broadband perfect absorber is designed, which is a simple-type structure composed of metal-dielectric-metal (MDM), and the resonant cavity formed by metal and dielectric realizes high absorption. The calculated results of the absorber show that the average absorption rate in the range of 200–8000 nm is 95.70%, and the absorption bandwidth over 90% is 7800 nm. The ultra-broadband absorption can be attributed to the coupling effect of multiple resonances inside and outside the resonant cavity, which gives our proposed structure a wider bandwidth and higher light absorption capacity than the previously reported work and further reduces the complexity of the structure. When it is replaced by other materials, the structure also maintains high absorbency. In addition, the structure is not only polarization insensitive but also has wide-angle absorption, and it maintains high absorption in transverse magnetic (TM) mode and transverse electric (TE) mode. Even when the incident angle increases to 58°, the average absorption rate is still above 80%. It also has the characteristics of large process tolerance and strong adaptability to changing environments. These results allow the absorber to be applied in solar energy collection, infrared imaging and thermal detection, and optoelectronic devices.

Design of Ultra-Broadband Metamaterial Absorber from Visible to Infrared Region

Design of Ultra-Broadband Metamaterial Absorber from Visible to Infrared Region

Ultra-broadband absorber based on photonic topological transition with large-[formula omitted] metals

We propose and experimentally demonstrate an ultra-broadband metamaterial absorber based on photonic topological transition by using metals with large real part of permittivity (ε′). The simulation results show that the absorptivity is larger than 0.9 in the wavelength range from 400 nm to 2832 nm. The simulation results also show that the absorption effect is insensitive to the incident angle and polarization. According to the effective medium theory, the ultra-broad bandwidth is originated from the photonic topological transition. In addition, the analyses reveal that the absorption bandwidths can be extended by manipulating the wavelengths of photonic topological transition (PTT) points with large-ε′ metals. Furthermore, an ultra-broadband metamaterial absorber with multilayer films is fabricated by using standard film deposition techniques. The measured results show that the absorptivity is larger than 0.9 under normal incidence over the measured wavelength range of 400–2500 nm. This metamaterial absorber is expected to be potential candidate for various applications, such as thermal photovoltaic energy conversion, detectors, and solar cells.

Photocontrolled ultra-broadband metamaterial absorber around the terahertz regime.

In this paper, we innovatively stack multiple resonant units of photoconductive silicon to design an ultra-broadband metamaterial absorber. By manipulating the conductivity of the silicon with a pump beam, adjustments are made to the amplitude of the wide absorption spectrum spanning 6.6 THz, enabling functional switching from total reflection to near-perfect ultra-broadband absorption. By integrating vanadium dioxide as an intermediary layer, a dual-mode switchable absorber is realized, offering dual control functionalities. Temperature changes enable the absorber to switch between dual-band absorption and ultra-broadband absorption, while variations in pump beam intensity allow for further amplitude adjustments within the absorption spectrum. Impedance matching theory and near-field analysis provide the necessary physical foundation for understanding broadband absorption. Structural parameters, incident angle, and polarization angle of the incident electromagnetic waves are also studied to demonstrate the device's robustness. Our proposed absorbers not only greatly broaden the absorption bandwidth of silicon-based absorbers, but also offer versatility, polarization insensitivity, and robustness over a wide range of incidence angles. Moreover, our design ideas are useful for broadening the bandwidth and enhancing absorption, which enables wider applications in ultra-broadband terahertz absorption and promises extensive prospects.

Design of metamaterial perfect absorbers in the long-wave infrared region.

We designed a narrow-band metamaterial absorber (NMA) and an ultra-broadband metamaterial perfect absorber (UMPA) based on the impedance matching theory. The narrow-band metamaterial absorber mainly consists of Si3N4 cylinders with Si3N4 and Ti substrates. Numerical analysis shows that the absorption peak of the NMA is about 99.9% and the absorption bandwidth with more than 90% absorption is about 4.8 μm (9.5-14.3 μm). To further extend the absorption bandwidth, an ultra-broadband absorber was designed by integrating a Ti hyperbolic rectangle into the Si3N4 cylinder of the NMA. Numerical analysis shows that the absorption bandwidth of the UMPA is up to 10 μm (7-17 μm) with an average absorption rate of 96.6%. The designed UMPA has polarization insensitive properties with wide-angle absorption characteristics, and the average absorption can reach 85% and 76% in transverse magnetic (TM) and transverse electric (TE) modes, respectively, at 60° oblique incidence. The high absorption and wide band are mainly dominated by localized surface plasmon resonance, Fabry-Perot resonance and inter-resonance interactions. The designed absorber achieves excellent absorption in the long infrared wavelength band, which has potential applications in energy absorption, infrared sensing and other fields.

Vanadium dioxide-based ultra-broadband metamaterial absorber for terahertz waves

An ultra-broadband, polarization-insensitive terahertz metamaterial absorber based on vanadium dioxide resonance structure is proposed in this paper. The device boasts advantages such as a straightforward design, broad absorption bandwidth, and substantial fractional bandwidth. Numerical simulations show that vanadium dioxide enables the absorber to achieve near-perfect absorption (with a rate greater than 95%) in its metallic state. It demonstrates an average absorption rate exceeding 96.5% across an ultra-broadband range (4.02 THz to 11.95 THz). The absorption bandwidth reaches 7.93 THz, with a relative bandwidth of 99.3%, representing a notable improvement over comparable absorbers. Furthermore, due to its highly symmetric pattern design, the device exhibits excellent polarization insensitivity and maintains stability even within a wide incident angle range. The operational mechanism of the absorber is elucidated through the application of impedance matching theory and near-field distribution analysis. The designed absorber structure makes vanadium dioxide materials more widely applicable in terahertz and ultra-broadband absorber devices, holding promising application prospects in fields such as security imaging, energy harvesting, and so on.

Design and Evaluation of Ultra-broadband Metamaterial Absorber for Energy Harvesting Applications

A perfect metamaterial absorber (MMA) is designed and evaluated numerically for solar energy harvesting applications. A dielectric layer separates the top structured metallic plane and the bottom ground metallic plane that make up the MMA. The MMA structure is primarily presented in the range of 100-1000 THz, which corresponds to 3000-300 nm in wavelength, for the efficient utilization of solar energy. The results obtained in the band 441-998 THz correspond to a visible and ultraviolet wavelength range of 680-300 nm. It has achieved a maximum absorption rate of 99.9% at 700 THz and 99% between 500 and 800 THz, respectively. In the desired frequency bands, the structure has achieved polarization and angle-resolved behavior. The MMA-based absorber has a high absorption rate of over 90% in the broadest visible (400-700 nm) and UV (100-300 nm) spectra. Also shown are the absorption characteristics of the MMA-based solar cell in the infrared (IR) region. The band 345-440 THz, corresponding to 870-690 nm, has 75% absorption. The other IR band (240-345 THz), which corresponds to 1250-880 nm, has achieved absorption of nearly 50%. So it can be utilized for the entire visible solar spectrum, including infrared to ultraviolet. If the proposed MMA structure were equipped with the appropriate electrical circuitry, it could be utilized for solar energyharvesting.

Ultra-broadband metamaterial absorber in the far infrared

To satisfy the requirements of infrared wide spectrum absorption, a metal–insulator-metal (MIM) metamaterial absorber is proposed and designed. Different from the ordinary MIM structure, the far-infrared (FIR) absorptivity is significantly improved through Cr/Si/Cr and periodic Cr ring design. The results of this research show that the structure has a high average absorptivity, which is up to 97.83 % in the FIR band range from 8 µm to 14 µm. And the absorptivity in the 7.93–11.47 µm band is greater than 99 %. The peak absorptivity can exceed 99.91 %. The absorber has excellent incidence angle insensitivity in TE and TM modes. The research results provide a reference for broadband FIR absorption designs.

An ultrabroadband metamaterial absorber based on remarkable magnetic coupling via constructing conductive composite resonators and magnetic gradient gyroid structure

ABSTRACT Broadband electromagnetic absorbing is still a challenge due to the huge difference of waves properties in different frequency bands. Herein, based on the transmission-line theory, we propose an in-plane hybrid metamaterial absorber using coupled resonators and gradient gyroid structure to realise the ultrabroadband absorbing. The coupled resonators based on Ag–Cu alloy/ABS conductive composite serve as transmission lines to orient the dipolar magnetic field, while the gradient gyroid structure fabricated by FCI/PEEK composite boosts the strong induced magnetic field. The unique hybrid strategy contributes to the remarkable magnetic coupling interaction, which not only realises good bandwidth extending effect, but also demonstrates the enhancement of absorbing efficiency. Finally, the 3D-printed hybrid metamaterial absorber achieves the high-efficiency absorbing in 2.2–40 GHz due to the electromagnetic field coupling resonance and synergistic loss effect. This absorber shows promising potential in real-life application by reasons of the low-frequency broadband absorption and convenient manufacturing.

Optically transparent conformal ultra-broadband metamaterial absorber based on ITO conductive film

An optically transparent metamaterial absorber with polarization insensitivity and wide-angle absorption is proposed. The absorber, which consists of an indium tin oxide resistive film and a low-loss substrate, is optically transparent and conformal. By tuning the reflection response of the frequency-selective surface and the thickness of the spacer layer, the whole structure achieves an absorption of more than 97% in the range of 6.54–18.66 GHz. Numerical simulation results show that the absorber can still maintain an absorption rate of more than 85% in a wide range of oblique incidence angles from 0° to 60°. In addition, the intrinsic physical mechanism of the absorber is elucidated using the impedance matching theory and the distribution of surface currents. The ratio of dielectric loss and ohmic loss is also quantitatively analyzed. Finally, the reflection and transmission coefficients of the sample were measured in a microwave anechoic chamber, which showed a good agreement with the simulation results. This design uses a low-resistivity resistive film as a frequency-selective surface, which was rarely involved in previous studies, and provides a new idea for future design and application.

Ultrabroadband vanadium-dioxide-based metamaterial absorber based on two resonance modes at a terahertz frequency

A terahertz (THz) ultrabroadband metamaterial absorber consisting of a periodically patterned vanadium dioxide (VO2) array, loss-free dielectric layer, and a continuous gold film is designed. Its resonance features can be dynamically tuned by applying different temperatures to the VO2 to promote phase transformation. When the VO2 is in the metallic state, the designed metamaterial has an absorption bandwidth of 6.08 THz with an absorptivity more than 90%, from 3.84 THz to 9.92 THz. The broadband absorption is attributed to the combination of two absorption peaks localized at 4.73 THz and 9.05 THz that are based on the localized resonance mode and surface lattice resonance mode. Taking advantage of the temperature phase transition of VO2, the designed absorber can be switched between ultrabroadband absorption and near-total reflection. Its maximum modulation depth can reach 99%, and it achieves an excellent modulation effect with a bandwidth of about 6 THz. The physical mechanism of the ultrabroadband absorption is discussed through an analysis of the near-field distribution and the current density distribution of the absorption peaks. The effect of structural parameters on the absorption are also investigated. The designed metamaterial absorber could have application potential in THz imaging, THz communications and smart devices.

Numerical Analysis of Ultra-broadband Metamaterial Absorber with High Absorption in the Visible and Infrared Regions

Numerical Analysis of Ultra-broadband Metamaterial Absorber with High Absorption in the Visible and Infrared Regions

Tunable ultra-broadband terahertz metamaterial absorber based on vanadium dioxide strips

A simple design of an ultra-broadband metamaterial absorber (MMA) of terahertz (THz) radiation based on vanadium dioxide (VO2) configurations is proposed. The system is composed of a top pattern representing orderly distributed VO2 strips, a dielectric spacer and an Au reflector. Theoretical analysis based on the electric dipole approximation is performed to characterize the absorption and scattering properties of an individual VO2 strip. The results then are used to design an MMA composed of such configurations. It is shown that the efficient absorption characteristics of the Au-insulator-VO2 metamaterial structure can be ensured in a broad spectrum of 0.66-1.84 THz with an absorption band relative to the center frequency reaching as high as 94.4%. The spectrum of the efficient absorption can be easily tuned via the corresponding choice of strip dimensions. Wide polarization and incidence angle tolerance for both transverse electric (TE) and transverse magnetic (TM) polarizations are ensured by adding an identical parallel layer rotated by 90 degrees in respect to the first one. Interference theory is applied to elucidate the absorption mechanism of the structure. The possibility of modulation of the electromagnetic response of MMA relying on the tunable THz optical properties of VO2 is demonstrated.

Ultra-broadband absorber based on metamaterial resonators utilizing particle swarm optimization algorithm

In this paper, we propose an ultra-broadband metamaterial absorber optimized by the particle swarm optimization (PSO) algorithm. A unit cell of the absorber is made of TiN/TiO2/TiN square disks, offering a metal-insulator-metal (MIM) configuration, surrounded by a TiN square ring resonator which all are located on a thin stack of TiO2/TiN films. The optimized structure shows high average absorption of 91.63% over the wavelength range of 200–4500 nm. The over 90% absorption bandwidth is 1590 nm, extended from 200 nm to 1790 nm. Furthermore, the absorber absorbs more than 80% of the incident light with wavelengths from 200 nm to 4480 nm, which covers the ultraviolet, visible, and near-infrared regions. The absorber indicates high absorptivity of over 75% under an oblique incidence up to 60° for both TM and TE polarizations. The effect of the presence of the square ring resonators as well as each layer of the MIM on the absorption of the absorber is also studied. It is shown that the use of square ring resonators combined with square disks significantly enhances the absorption of the absorber at wavelengths longer than 1100 nm. The structure has high thermal and chemical stability due to the use of TiN and TiO2. Owing to the outstanding features of the proposed absorber, it can be used in different fields such as imaging, thermal emitting, and solar applications.

Design and Parametric Analysis of a Wide-Angle and Polarization Insensitive Ultra-Broadband Metamaterial Absorber for Visible Optical Wavelength Applications

Researchers are trying to work out how to make a broadband response metamaterial absorber (MMA). Electromagnetic (EM) waves that can pass through the atmosphere and reach the ground are most commonly used in the visible frequency range. In addition, they are used to detect faults, inspect tapped live-powered components, electrical failures, and thermal leaking hot spots. This research provides a numerical analysis of a compact split ring resonator (SRR) and circular ring resonator (CRR) based metamaterial absorber (MMA) using a three-layer substrate material configuration for wideband visible optical wavelength applications. The proposed metamaterial absorber has an overall unit cell size of 800 nm × 800 nm × 175 nm in both TE and TM mode simulations and it achieved above 80% absorbance in the visible spectrums from 450 nm to 650 nm wavelength. The proposed MA performed a maximum absorptivity of 99.99% at 557 nm. In addition, the steady absorption property has a broad range of oblique incidence angle stability. The polarization conversion ratio (PCR) is evaluated to ensure that the MMA is perfect. Both TM and TE modes can observe polarization insensitivity and wide-angle incidence angle stability with 18° bending effects. Moreover, a structural study using electric and magnetic fields was carried out to better understand the MMA's absorption properties. The observable novelty of the proposed metamaterial is compact in size compared with reference paper, and it achieves an average absorbance of 91.82% for visible optical wavelength. The proposed MMA also has bendable properties. The proposed MMA validation has been done by two numerical simulation software. The MMA has diverse applications, such as color image, wide-angle stability, substantial absorption, absolute invisible layers, thermal imaging, and magnetic resonance imaging (MRI) applications.

Ultra-broadband wave-absorbing metamaterials with open-hole effect

In this paper, propose the open-hole effect, which can improve the absorption effect of electromagnetic absorbers in the X- and Ku-band by regularly opening certain shaped through-holes in the dielectric material. Based on this effect, an ultra-wideband metamaterial absorber with a special open-hole structure is designed and successfully prepared by numerical simulation, and the effective wavelength bandwidth (absorption > 90 %) covers X- and Ku-band. By optimizing the dielectric material and structural parameters of the absorber, an ultra-broadband metamaterial absorber with a thickness of 2.2 mm, a maximum absorption rate of 99.35 % and an effective absorption bandwidth of 11.6 GHz was obtained. Simulations of TE and TM waves at different angles show that the absorber has excellent electromagnetic wave absorption at different angles of incidence (θ < 30°).

Ultra-broadband metamaterial perfect solar absorber with polarization-independent and large incident angle-insensitive

Broadband metamaterial perfect absorbers have attracted a great attention to the people who study its use in solar energy harvesting. However, it is an extremely challenge to integrate such properties as ultra-broadband, perfect absorption, polarization-independent, angle-insensitive to a large incident angle and so on into a simple absorber structure. In this paper, we use FDTD to design a simple ultra-broadband metamaterial perfect absorber, consisting of x-cavity titanium nano-disk array based on a Silicon nitride-Titanium-Silicon nitride-Titanium four-layer structure. The optimized results indicate that the absorber broadband absorption spectra range from 400 nm to 2500 nm with 97.6% average absorption at normal incidence. The interactions among SPR, MR and CR lead to a high absorption. Moreover, the absorber is both polarization-independent and large incident angle-insensitive for both TE and TM-polarized waves. In addition, the absorber has an extremely high tolerance to fabrication errors, which is of great significance for practical production and application.