Near-unity Absorption Research Articles

Theoretical and numerical investigation of an ultra-broadband near-perfect absorption in auxetic metamaterials

In this paper, we present and numerically investigate an auxetic metamaterial absorber based on vanadium dioxide (VO2), achieving more than 90% absorption of the incident terahertz (THz) waves between 4.15 THz to 8.43 THz with an average absorption of 98.4%. To our knowledge, the absorption bandwidth is higher than previously reported VO2-based absorbers. The proposed absorber contains two VO2 based resonator rings placed diagonally at the top of the dielectric substrate in such a way as to create an auxetic shape and provide more design space than the existing absorbers. Considering the vector nature of electromagnetic fields in three-dimensional space, numerical analysis is performed while keeping the phase-changing material VO2 in the metallic state. According to the full wave simulation, it is shown that under normal incidence, the proposed absorber provides almost flat and near-unity absorption, which covers from 4.82 THz to 7.53 THz. We describe the physical mechanism of the absorber through impedance matching theory, and the absorber performance is evaluated by observing the electric field distributions at various frequencies. The proposed structure also exhibits a satisfactory tunable range from 2% to 100%, which may satisfy the requirements of re-configurable metamaterial absorbers. We also show that the absorber provides better wide-angle absorption performance than the existing VO2-based models for both transverse polarization i.e., transverse electric (TE) and transverse magnetic (TM) modes. Owing to the higher absorption bandwidth and better tunable range, the proposed auxetic metamaterial has great potential applications in THz imaging, detectors, and sensing.

Broadband Solar Absorber and Thermal Emitter Based on Single-Layer Molybdenum Disulfide.

In recent years, solar energy has become popular because of its clean and renewable properties. Meanwhile, two-dimensional materials have become a new favorite in scientific research due to their unique physicochemical properties. Among them, monolayer molybdenum disulfide (MoS2), as an outstanding representative of transition metal sulfides, is a hot research topic after graphene. Therefore, we have conducted an in-depth theoretical study and design simulation using the finite-difference method in time domain (FDTD) for a solar absorber based on the two-dimensional material MoS2. In this paper, a broadband solar absorber and thermal emitter based on a single layer of molybdenum disulfide is designed. It is shown that the broadband absorption of the absorber is mainly due to the propagating plasma resonance on the metal surface of the patterned layer and the localized surface plasma resonance excited in the adjacent patterned air cavity. The research results show that the designed structure boasts an exceptional broadband performance, achieving an ultra-wide spectral range spanning 2040 nm, with an overall absorption efficiency exceeding 90%. Notably, it maintains an average absorption rate of 94.61% across its spectrum, and in a narrow bandwidth centered at 303 nm, it demonstrates a near-unity absorption rate, surpassing 99%, underscoring its remarkable absorptive capabilities. The weighted average absorption rate of the whole wavelength range (280 nm-2500 nm) at AM1.5 is above 95.03%, and even at the extreme temperature of up to 1500 K, its heat radiation efficiency is high. Furthermore, the solar absorber in question exhibits polarization insensitivity, ensuring its performance is not influenced by the orientation of incident light. These advantages can enable our absorber to be widely used in solar thermal photovoltaics and other fields and provide new ideas for broadband absorbers based on two-dimensional materials.

Symmetric engineered central cross-shaped broadband metamaterial absorber with high absorption and stability for solar sailing and solar energy applications

We propose a theoretical design and analysis of a broadband metamaterial absorber (MMA) with significant potential for solar sailing applications which is a method of spacecraft propulsion that usages the momentum of sunlight to propel a spacecraft through space. The absorber features a metal-dielectric-metal configuration with a tungsten (W) based resonator and ground plane, and a Silicon-dioxide (SiO₂) substrate. Addressing the critical need for materials that can efficiently harness solar radiation for propulsion in space, our design achieves an average absorption of 99.15 % over a broad spectrum from 250 nm to 1200 nm, covering the UV–Visible–NIR regions, with near-unity absorption peaks at 362 nm and 915.8 nm. It maintains high absorptions of 84.9 % and 86 % under transvers electric and transvers magnetic modes respectively, demonstrating excellent wide incident angle stability and polarization insensitivity due to its symmetric design. PCR values close to zero confirm its functionality as an absorber rather than a polarizer. The MMA shows minimal deformation across temperatures from 500 K to 1750 K and remains stable under various mechanical stresses, proving its durability and efficiency in space. Additionally, in solar thermophotovoltaic (STPV) systems, the MMA demonstrates high photothermal conversion efficiency (PTCE) over a wide temperature range (500 °C to 1500 °C) and different concentration factors. This dual functionality highlights its potential for both efficient space exploration and terrestrial solar energy harvesting, making it a versatile tool for future technological applications.

Polarization-insensitive terahertz third-harmonic generation from degenerate pairs of mirror-coupled super-BICs

Resonant nanostructures have emerged as versatile photonic platforms for boosting optical nonlinear responses on a subwavelength scale for their ability to confine intense electromagnetic fields while relaxing the phase-matching requirements. Recent significant advances in this field are associated with the utilization of non-radiative eigenmodes above the light cone, termed bound states in the continuum (BICs), which provide a unique mechanism for light trapping to realize excitation of ultrahigh quality (Q) factor resonances. Nevertheless, the current studies on BICs predominantly focus on symmetry-protected BICs (SP-BICs), whose excitation requires symmetry breaking, and Q factors are limited by fabrication imperfections. Here, we demonstrate a simple and feasible scheme for creating degenerate pairs of mirror-coupled super-BICs by harnessing magnetic dipole resonances coupled to their mirror images in adjacent metal films. Unlike trivial SP-BICs, mirror-coupled BICs showcases the huge enhancement of Q factors and are resilient against fabrication imperfections. By combining mirror-coupled resonance with the engineered radiative loss, we obtain a perfect absorber with near-unity absorption and ultra-narrow bandwidth at a critical coupling condition. Finally, we numerically demonstrate the terahertz (THz) regime, polarization-insensitive highly efficient third-harmonic generation benefiting from the maximum field enhancement localized within the perfect absorber. Our work not only paves the way toward unlocking the full potential of BIC resonance but also promise valuable insights for developing efficient THz optoelectronic devices and metadevices across a wide range of fields.

Metasurface-enhanced photochemical activity in visible light absorbing semiconductors.

Heterogeneous photocatalysis is an important research problem relevant to a variety of sustainable energy technologies. However, obtaining high photocatalytic efficiency from visible light absorbing semiconductors is challenging due to a combination of weak absorption, transport losses, and low activity. Aspects of this problem have been addressed by multilayer approaches, which provide a general scheme for engineering surface reactivity and stability independent of electronic considerations. However, an analogous broad framework for optimizing light-matter interactions has not yet been demonstrated. Here, we establish a photonic approach using semiconductor metasurfaces that is highly effective in enhancing the photocatalytic activity of GaAs, a high-performance semiconductor with a near-infrared bandgap. Our engineered pillar arrays with heights of ∼150nm exhibit Mie resonances near 700nm that result in near-unity absorption and exhibit a field profile that maximizes charge carrier generation near the solid-liquid interface, enabling short transport distances. Our hybrid metasurface photoanodes facilitate oxygen evolution and exhibit enhanced incident photon-to-current efficiencies that are ∼22× larger than a corresponding thin film for resonant excitation and 3× larger for white light illumination. Key to these improvements is the preferential generation of photogenerated carriers near the semiconductor interface that results from the field enhancement profile of magnetic dipolar-type modes.

Near-Unity Light-Matter Interaction in Mid-Infrared van der Waals Metasurfaces.

Accessing mid-infrared radiation is of great importance for a range of applications, including thermal imaging, sensing, and radiative cooling. Here, we study light interaction with hexagonal boron nitride (hBN) nanocavities and reveal strong and tunable resonances across its hyperbolic transition. In addition to conventional phonon-polariton excitations, we demonstrate that the high refractive index of hexagonal boron nitride outside the Reststrahlen band allows enhanced light-matter interactions in deep subwavelength (<λ/15) nanostructures across a broad 7-8 μm range. Emergence and interplay of Fabry-Perot and Mie-like resonances are examined experimentally and theoretically. Near-unity absorption and high quality (Q ≥ 80) resonance interaction in the vicinity of the hBN transverse optical phonon is further observed. Our study provides avenues to design highly efficient and ultracompact structures for controlling mid-infrared radiation and accessing strong light-matter interactions with hBN.

An efficient, compact, wide-angle, wide-band, and polarization-insensitive metamaterial electromagnetic energy harvester

This paper introduces a metamaterial energy harvester that is compact, highly efficient, and capable of operating at wide angles. The proposed design has an outer ring resonator housing inverted T-shaped resonators, and it can operate at two distinct frequencies, 3.2 GHz and 5.4 GHz. The structure's impedance is carefully designed to align with that of free space, ensuring efficient capture of incident electromagnetic power with minimal reflection. This enables the resistor load to receive power in the most efficient manner. Based on the simulation findings, the proposed harvester exhibits a notably higher conversion efficiency of around 97 %. To ensure the accuracy and reliability of the simulation outcomes, we fabricated a 3x3 cell array of the proposed design and conducted experimental tests within an anechoic chamber. The simulation and experimental results exhibit a strong correlation. Existing metamaterial-based energy harvesting designs frequently confront size, absorption band, and polarization sensitivity limitations. Our compact design is distinguished by its ability to accomplish near-unity absorption and greater power conversion efficiencies at the desired frequency bands. This makes it an ideal option for energy harvesting systems for wireless sensor networks prioritizing efficiency and size.

Towards fiber-coupled plasmonic perfect absorber superconducting nanowire photodetectors for the near- and mid-infrared

Modern photon-based technologies are in need for fast detectors with the ability to detect photons in the near- and mid-IR efficiently. Superconducting nanowire photon detectors, which use the resistivity change upon photon incidence caused by a state transition from their superconducting to normal conducting phase, are state-of-the-art detectors. However, detectors usually suffer from low efficiency in the IR, due to their low intrinsic absorption in this spectral range. To enhance the detection efficiency, we use a plasmonic perfect absorber geometry, which utilizes a localized surface plasmon resonance and a spacer/mirror combination. We present superconducting niobium plasmonic perfect absorber nanostructures, featuring near-unity absorption, tailorable up to wavelengths of 4 µm. Further, we confirm the working principle of the plasmonic perfect absorber for wavelengths in the near-IR, which manifests itself as a polarization-dependent detector response. Finally, we demonstrate an approach of coupling the detector directly to a fiber. This might also enable ultrasensitive sensing application in the near- and mid-IR in the future.

Polarization- and angle-insensitive broadband long wavelength infrared absorber based on coplanar four-sized resonators.

In many potential applications, there is a high demand for long wavelength infrared (LWIR) absorbers characterized by a compact configuration, broad operational bandwidth, high absorption efficiency, and polarization- and angle-insensitive characteristics. In this study, we design and demonstrate a high-performance broadband LWIR absorber based on coplanar four-sized resonators, consisting of arrays of titanium (Ti) disks with different diameters supported by a continuous zinc selenide (ZnSe) layer and by a Ti film acting as a back-reflector. Particle swarm optimization (PSO) is employed to optimize the complicated geometry parameters, and the final optimized device exhibits near-unity absorption (∼96.7%) across the entire operational bandwidth (8 µm∼14 µm) under unpolarized normal incidence, benefiting from the impedance-matching condition and the multiple surface plasmon resonances of this configuration. Furthermore, the proposed absorber is insensitive to the angle of incidence due to the localized surface plasmon resonances supported by these four-sized resonators, and is insensitive to the state of polarization thanks to the highly symmetric feature of the circular pattern. The measured absorption of the fabricated sample exhibits a relatively high coincidence with the simulation, with an average absorption of 88.9% ranging from 8 µm to 14 µm. The proposed absorber, which can be easily integrated into a standardized micro/nano manufacture process for cost-effective large-scale production, provides a feasible solution for improving optical performance in thermal emitter, infrared detection, and imaging applications. Furthermore, the generalized design principle employing the optimized method opens up new avenues for realizing target absorption, reflection, and transmission based on more complicated structure configurations.

Spatial and frequency-selective optical field coupling absorption in an ultra-thin random metasurface.

Simplified thin-film structures with the capability of spatial and frequency-selective optical field coupling and absorption are desirable for nanophotonics. Herein, we demonstrate the configuration of a 200-nm-thick random metasurface formed by refractory metal nanoresonators, showing near-unity absorption (absorptivity > 90%) covering the visible and near-infrared range (0.380-1.167 µm). Importantly, the resonant optical field is observed to be concentrated in different spatial areas according to different frequencies, paving a feasible way to artificially manipulate spatial coupling and optical absorption via the spectral frequency. The methods and conclusions derived in this work are applicable throughout a wide energy range and hold applications for frequency-selective nanoscale optical field manipulation.

Perfect absorption based on Ti3C2Tx surface plasmon resonance

As a kind of emerging two-dimensional material, Ti3C2Tx possesses metal-like property, which can be utilized to generate strong surface plasmon resonance in optical regime. In this paper, a perfect metamaterial absorber (BPMA) is proposed, which consists of the top Ti3C2Tx layer, the middle SiO2 layer and the bottom gold layer. The BPMA with the simple structure can achieve perfect (near-unity) absorption ranging from 693 nm to 897 nm. The electric field distribution reveals that the perfect absorption in this wavelength range is attributed to localized surface plasmon resonance produced by Ti3C2Tx. Furthermore, the perfect absorption exhibits good stability to polarization and incident angles. The calculated absorptivity based on interference theory agrees well with the simulation result, thereby demonstrating the design. This work provides a simple method to achieve perfect absorption across a wavelength range in visible and near-infrared regions.

Bound states in the continuum enabling ultra-narrowband perfect absorption

Resonant dielectric metasurfaces have been demonstrated to hold a great promise for manipulation of light-wave dispersion at the nanoscale due to their resonant photonic environment and high refractive index. However, the efficiency of devices based on dielectric nanostructures is usually limited by the quality (Q) factor of their resonant modes. The physics of the bound sates in the continuum (BICs) provide an elegant solution for control over the Q factor of resonant modes. Here, by engineering the substrate of Si-based metasurfaces, we demonstrate two eigenmodes that exhibit an intrinsic magnetic dipole (MD)character and have an infinite radiation lifetime. We reveal that they are characterized by in-plane and out-of-plane MD modes and respectively correspond to two groups of BICs, that is, Fabry–Pérot BICs and symmetry-protected BICs. Using temporal coupled-mode theory and numerical simulations, we show that these BIC modes can transform into high-Q quasi-BIC resonances with near-unity absorption under normal incidence through tuning structural parameters. Our work provides a promising route to use BIC-inspired metasurfaces for designing ultra-narrowband absorbers which can be used as absorption filters, photodetectors, and sensors.

Broadband near unity absorption meta-structure for solar thermophotovoltaic systems and optical window applications.

Developing a meta-structure with near-unity absorbance in the visible and infrared spectra for solar energy harvesting, photodetection, thermal imaging, photo-trapping, and optical communications is a long-term research challenge. This research presents a four-layered (insulator-metal-insulator-metal) meta-structure unit cell that showed a peak absorbance of 99.99% at 288-300 nm and the average absorbance of 99.18% over the 250-2000 nm wavelength range in TE and TM modes, respectively. The symmetric pattern of the resonator layer shows polarization insensitivity with an average absorption of 99.18% in both TE and TM modes. Furthermore, the proposed design shows a wide incident angle stability up to ≤60 degrees in both TE and TM modes. The proposed structure also exhibits negative index properties at 288-300 nm and 1000-2000 nm, respectively. The negative index properties of the proposed design generate an anti-parallel surface current flow in the ground and resonator layers, which induces magnetic and electric field resonance and increases absorption. The performance of the proposed design is further validated by the interference theory model and a zero value for the polarization conversion ratio (PCR). The electric field E, magnetic field H, and current distribution are analyzed to explain the absorption mechanism of the proposed meta-structure unit cell. It also exhibits the highest photo-thermal conversion efficiency of 99.11%, demonstrating the viability of the proposed design as a solar absorber. The proposed design promises potentially valuable applications such as solar energy harvesting, photodetection, thermal imaging, photo-trapping, and optical communications because of its decent performance.

Polarization-Insensitive Absorptive/Transmissive Reconfigurable Frequency Selective Surface With Embedded Biasing

In this letter, a polarization-insensitive absorptive/transmissive reconfigurable frequency selective surface (RFSS) using p-i-n diodes is presented. The RFSS structure incorporates two periodically arranged metallic patterns on both sides of an FR4 dielectric substrate, where the p-i-n diodes are aligned symmetrically on the bottom surface. Depending upon the diode biasing conditions, the geometry behaves as a radar absorber and a bandpass filter under different working states. The simulated response exhibits a near-unity absorption response (having absorptivity of 93.51%) at 6.93 GHz during <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> state of the diode, whereas the incident electromagnetic wave gets transmitted through the structure at 5.62 GHz during <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> state. An embedded biasing circuitry has also been developed comprising metallic vias and inductors, such that the geometry displays polarization-insensitive and angularly stable responses for both states. The structure has been analyzed with the help of circuit modeling and other parametric variations to explain the switching methodology. A prototype has been fabricated and measured using the parallel-plate waveguide technique, which results in a good agreement with the simulated responses. Such RFSSs can be marked as a potential element for various radome applications.

Transparent Thermally Tunable Microwave Absorber Prototype Based on Patterned VO2 Film

Transparent microwave absorbers that exhibit high optical transmittance and microwave absorption capability are ideal, although having a fixed absorption performance limits their applicability. Here, a simple, transparent, and thermally tunable microwave absorber is proposed, based on a patterned vanadium dioxide (VO2) film. Numerical calculations and experiments demonstrate that the proposed VO2 absorber has a high optical transmittance of 84.9% at 620 nm; its reflection loss at 15.06 GHz can be thermally tuned from –4.257 to –60.179 dB, and near-unity absorption is achieved at 523.750 K. Adjusting only the patterned VO2 film duty cycle can change the temperature of near-unity absorption. Our VO2 absorber has a simple composition, a high optical transmittance, a thermally tunable microwave absorption performance, a large modulation depth, and an adjustable temperature tuning range, making it promising for application in tunable sensors, thermal emitters, modulators, thermal imaging, bolometers, and photovoltaic devices.

Metamaterial solar absorber based on titanium resonators for operation in the ultraviolet to near-infrared region

In this work, we design an ultra-broadband metamaterial solar absorber with near-unity absorption. The absorber’s structure is optimized by using the particle swarm optimization algorithm. A unit cell of the absorber consists of three T i / T i O 2 / T i square disks enclosed by a Ti square ring resonator, all superimposed on a thin stack of T i O 2 / T i films. The optimized structure shows high average absorption of 96.92% over the full wavelength range of 200–3200 nm. The over 90% absorption bandwidth is 3000 nm, which covers the ultraviolet, visible, and near-infrared regions. The solar absorption of the structure is 95.5% in the range of 280–3200 nm. The absorber is polarization independent and insensitive to incident angle changes. The absorption remains higher than 80% and 75% for TM and TE polarizations, respectively, even under oblique incidence radiation up to 55°. The structure possesses high thermal and chemical stability owing to the use of Ti and T i O 2 materials. Due to its outstanding features, the absorber has high potential to be used in solar energy harvesting, thermo-photovoltaics, and thermal emitting applications.

Surface plasmon resonance-enhanced broadband perfect absorption in a Ti3C2Tx-based metamaterial absorber

The absorption band in which near-unity or perfect absorption can be realized is still narrow in the current broadband metamaterial absorbers (BMAs). In this article, a broadband perfect metamaterial absorber (BPMA) based on surface plasmon resonance (SPR) is proposed for the visible and near-infrared range. The BPMA composed of a patterned Ti3C2Tx layer, SiO2 layer and the ground gold layer can offer over 90% absorption across the wavelength range of 639–967 nm. It is worth noting that near-unity absorption can be achieved in the range 728–890 nm, which is out of reach by the currently reported BMA. The electric field distribution reveals that localized SPR generated by the Ti3C2Tx layer contributes to the broadband perfect absorption. Additionally, the BPMA is insensitive to incident and polarized angles at TE and TM modes. The calculated results based on interference theory agree well with the simulation results, thus supporting the design. This work may provide a potential approach to broadband perfect absorption in the visible and near-infrared region.

Visible light metasurface for adaptive photodetection

Semiconductor-based sub-wavelength metasurfaces are promising device platforms for the realization of optically thick and electrically thin photodetectors. Strong light–matter interactions in ultrathin film regions provide an opportunity to achieve near-unity absorption in dimensions comparable with carrier diffusion length and this, in turn, leads to an efficient collection of photogenerated carriers. Moreover, the use of phase change materials can provide real-time active tuning of optical responses of metasurface-based devices. In the first part of this paper, a tunable color filtering device is demonstrated using a metasurface design made of sub-wavelength antimony trisulphide (Sb2S3) grating placed on top of a continuous silver layer. Four distinct optical states can be acquired upon (a) the changes in the incident light polarization and (b) the phase transitions of Sb2S3. Numerical simulations and theoretical modeling data show that Fabry–Perot resonances are the driving phenomena when the proposed design is normally illuminated by an electromagnetic field with transverse electric polarization. In contrast, surface plasmon resonances are excited in transverse magnetic polarization. Furthermore, it is shown that the resonance wavelengths of the proposed design can be dynamically tuned using the geometrical parameters. Later, in the second part of the paper, adaptive photodetection is designed by integrating a nm Sb2S3 layer as a collection layer into the structure. The proposed metasurface design provides light–matter interaction in the Sb2S3 layer and maximizes the photogenerated carriers’ collection efficiency. The optically thick and electrically thin adaptive photodetection offers an opportunity to design efficient active optoelectronic and photonic devices.

Novel Dual-Mode Polarization Insensitive Wide Angular Stable Circular Ring Based Deca-Band Absorber for RCS and EMI Shielding Applications

A simple concentric circular ring resonator-based nonreciprocal deca-band absorber is demonstrated in this article. The design primarily consists of two frequency selective surfaces (FSSs) among one is a compliment to the other printed on either side of the 2.4 mm thin FR-4 dielectric substrate. It exhibits near-unity absorption effectively at ten different resonant frequencies over X-Ka bands with an average absorption efficiency of 94.6%. Surface plasmonic resonances are the reason behind the multiband absorption and are illustrated with current profiles at resonant frequencies. The performance is angular stable for both transverse electric and transverse magnetic oblique incidences up to 60 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> . The design is compact with a structural periodicity of 0.210 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\boldsymbol{\lambda }}}_{\boldsymbol{o}}$</tex-math></inline-formula> and thickness 0.07 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\boldsymbol{\lambda }}}_{\boldsymbol{o}}$</tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\boldsymbol{\lambda }}}_{\boldsymbol{o}}$</tex-math></inline-formula> is the lowest resonant peak's free-space wavelength. The 20×20 array of the design prototype is fabricated, and the measured results agree with the full-wave analysis. Bistatic radar cross section (RCS) analysis of the proposed absorber is evaluated along with a conventional microstrip patch antenna at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band. Since the absorber design is based on complementary FSSs, it can also be utilized as a reflector for the not absorbing frequencies. The novelty lies in the utilization of the dual-side of the substrate made this design compact with a greater number of absorption peaks and good angular stability, making it potential for real-time RCS, and electromagnetic interference and shielding applications.

A Miniaturized 3-D Metamaterial Absorber With Wide Angle Stability

A miniaturized metamaterial absorber (MA) based on 3-D resonant structures is presented. The absorber exhibits near-unity absorption (>99%) at 2.08 GHz, thanks to the long electric length of the folded metal plate. The proposed structure has a unit cell size of 7 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 7 mm, which gives a ratio between periodicity and resonance wavelength of 1/20.6. Moreover, the proposed structure maintains absorption above 90% with incident angle reaching up to 60° and 70° for TE and TM polarizations, respectively. The stereo resonator and dielectric substrate included in this absorber are fabricated with the aid of the multimaterial hybrid microdroplet jetting modeling (MHMJM) technique. The measured absorption spectrum agrees closely with the simulations.