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15 pages, 25729 KiB

Open AccessArticle

A Polarization-Insensitive, Vanadium Dioxide-Based Dynamically Tunable Multiband Terahertz Metamaterial Absorber

by Mohsin Raza, Xiaoman Li, Chenlu Mao, Fenghua Liu, Hongbo He and Weiping Wu

Materials 2024, 17(8), 1757; https://doi.org/10.3390/ma17081757 - 11 Apr 2024

Cited by 3 | Viewed by 1540

A tunable multiband terahertz metamaterial absorber, based on vanadium dioxide (VO₂), is demonstrated. The absorber comprises a three-layer metal–insulator–metal (MIM) configuration with a split ring and slots of VO₂ on the uppermost layer, a middle dielectric substrate based on silicon [...] Read more.

A tunable multiband terahertz metamaterial absorber, based on vanadium dioxide (VO₂), is demonstrated. The absorber comprises a three-layer metal–insulator–metal (MIM) configuration with a split ring and slots of VO₂ on the uppermost layer, a middle dielectric substrate based on silicon dioxide (SiO₂), and a gold reflector on the back. The simulation results indicate that, when VO₂ is in the metallic state, the proposed metamaterial exhibits nearly perfect absorption at six distinct frequencies. The design achieves an average absorption of 98.2%. The absorptivity of the metamaterial can be dynamically tuned from 4% to 100% by varying the temperature-controlled conductivity of VO₂. The proposed metamaterial absorber exhibits the advantages of polarization insensitivity and maintains its absorption over 80% under different incident angle conditions. The underlying physical mechanism of absorption is explained through impedance matching theory, interference theory, and the distribution of electric fields. The ability to achieve multiband absorption with tunable characteristics makes the proposed absorber a promising candidate for applications in terahertz sensing, imaging, communication, and detection. The polarization insensitivity further enhances its practicality in various scenarios, allowing for versatile and reliable performance in terahertz systems. Full article

(This article belongs to the Special Issue Design and Applications of Terahertz Metamaterials)

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10 pages, 4125 KiB

Open AccessArticle

Near-Infrared Perfect Absorption and Refractive Index Sensing Enabled by Split Ring Nanostructures

by Wajid Ali, Weitao Liu, Ye Liu and Ziwei Li

Nanomaterials 2023, 13(19), 2668; https://doi.org/10.3390/nano13192668 - 28 Sep 2023

Cited by 3 | Viewed by 1761

Abstract

Plasmonic nanostructures as narrowband perfect absorbers have garnered significant attention due to their potential applications in biosensing and environment detection. This study emphasizes the investigation of arrayed split ring nanostructures within the configuration of metal-insulator-metal (MIM) multilayers, resulting in a maximum light absorption [...] Read more.

Plasmonic nanostructures as narrowband perfect absorbers have garnered significant attention due to their potential applications in biosensing and environment detection. This study emphasizes the investigation of arrayed split ring nanostructures within the configuration of metal-insulator-metal (MIM) multilayers, resulting in a maximum light absorption of 99.94% in the near-infrared (NIR) spectral range. The exceptional absorption efficiency of the device is attributed to the strong resonance of electric and magnetic fields arising from the Fabry–Pérot cavity resonance. The resonant peak can be flexibly tuned by engineering the dielectric layer thickness, the period, and the geometric parameter of split rings. Remarkably, the device exhibits promising capabilities in sensing, demonstrating a sensitivity of 326 nm/RIU in visible wavelengths and 504 nm/RIU in NIR wavelengths when exposed to bio-analytes with varying refractive indices. This designed nanostructure can serve as a promising candidate for biosensors or environmental detection. Full article

(This article belongs to the Special Issue Synthesis and Application of Optical Nanomaterials)

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9 pages, 3218 KiB

Open AccessArticle

Broadband and Wide-Angle Performance of a Perfect Absorber Using a MIM Structure with 2D MXene

by Yue Jia, Chunmei Song, Yunlong Liao and Houzhi Cai

Electronics 2022, 11(9), 1370; https://doi.org/10.3390/electronics11091370 - 25 Apr 2022

Cited by 11 | Viewed by 2391

Abstract

Due to the extraordinary optoelectronic properties and surface-rich functional groups, MXene has shown great promise in many applications, such as electromagnetic shielding, catalysis, sensors, ultrafast photons, etc. In this work, we propose a wide-angle absorber based on a metal-insulator-metal (MIM) metamaterial consisting of [...] Read more.

Due to the extraordinary optoelectronic properties and surface-rich functional groups, MXene has shown great promise in many applications, such as electromagnetic shielding, catalysis, sensors, ultrafast photons, etc. In this work, we propose a wide-angle absorber based on a metal-insulator-metal (MIM) metamaterial consisting of MXene. By optimizing the design, the absorption efficiency can be further improved throughout the entire wavelength range. More importantly, the absorber exhibits high-efficiency broadband and wide-angle (20–80°) absorption in the near-infrared range (NIR: 1.1–1.7 μm) by numerical calculation. It is foreseeable that the excellent absorption characteristics and easy-to-manufacture structure of the designed absorber will bring some inspiration to the absorption device in the NIR and its practical application. Full article

(This article belongs to the Special Issue Digital and Optical Security Algorithms via Machine Learning)

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11 pages, 2549 KiB

Open AccessArticle

Fabrication of Infrared-Compatible Nanofluidic Devices for Plasmon-Enhanced Infrared Absorption Spectroscopy

by Thu Hac Huong Le, Takumi Matsushita, Ryoichi Ohta, Yuta Shimoda, Hiroaki Matsui and Takehiko Kitamori

Micromachines 2020, 11(12), 1062; https://doi.org/10.3390/mi11121062 - 30 Nov 2020

Cited by 4 | Viewed by 2884

Abstract

Nanofluidic devices have offered us fascinating analytical platforms for chemical and bioanalysis by exploiting unique properties of liquids and molecules confined in nanospaces. The increasing interests in nanofluidic analytical devices have triggered the development of new robust and sensitive detection techniques, especially label-free [...] Read more.

Nanofluidic devices have offered us fascinating analytical platforms for chemical and bioanalysis by exploiting unique properties of liquids and molecules confined in nanospaces. The increasing interests in nanofluidic analytical devices have triggered the development of new robust and sensitive detection techniques, especially label-free ones. IR absorption spectroscopy is one of the most powerful biochemical analysis methods for identification and quantitative measurement of chemical species in the label-free and non-invasive fashion. However, the low sensitivity and the difficulties in fabrication of IR-compatible nanofluidic devices are major obstacles that restrict the applications of IR spectroscopy in nanofluidics. Here, we realized the bonding of CaF₂ and SiO₂ at room temperature and demonstrated an IR-compatible nanofluidic device that allowed the IR spectroscopy in a wide range of mid-IR regime. We also performed the integration of metal-insulator-metal perfect absorber metamaterials into nanofluidic devices for plasmon-enhanced infrared absorption spectroscopy with ultrahigh sensitivity. This study also shows a proof-of-concept of the multi-band absorber by combining different types of nanostructures. The results indicate the potential of implementing metamaterials in tracking several characteristic molecular vibrational modes simultaneously, making it possible to identify molecular species in mixture or complex biological entities. Full article

(This article belongs to the Special Issue Advances in Nanofluidics)

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10 pages, 40741 KiB

Open AccessArticle

Detailed Experiment-Theory Comparison of Mid-Infrared Metasurface Perfect Absorbers

by Naoki To, Saulius Juodkazis and Yoshiaki Nishijima

Micromachines 2020, 11(4), 409; https://doi.org/10.3390/mi11040409 - 14 Apr 2020

Cited by 29 | Viewed by 5514

Abstract

Realisation of a perfect absorber

A = 1

with transmittance and reflectance

T = R = 0

by a thin metasurface is one of the hot topics in recent nanophotonics prompted by energy harvesting and sensor applications ( [...] Read more.

Realisation of a perfect absorber

A = 1

with transmittance and reflectance

T = R = 0

by a thin metasurface is one of the hot topics in recent nanophotonics prompted by energy harvesting and sensor applications (

A + R + T = 1

is the energy conservation). Here we tested the optical properties of over 400 structures of metal–insulator–metal (MIM) metasurfaces for a range of variation in thickness of insulator, diameter of a disc and intra-disc distance both experimentally and numerically. Conditions of a near perfect absorption

A > 95 %

with simultaneously occurring anti-reflection property (

R < 5 %

) was experimentally determined. Differences between the bulk vs. nano-thin film properties at mid-IR of the used materials can be of interest for plasmonic multi-metal alloys and high entropy metals. Full article

(This article belongs to the Special Issue Micro/Nano-surfaces: Fabrication and Applications)

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10 pages, 2996 KiB

Open AccessArticle

A Perfect Absorber Based on Similar Fabry-Perot Four-Band in the Visible Range

by Pinghui Wu, Congfen Zhang, Yijun Tang, Bin Liu and Li Lv

Nanomaterials 2020, 10(3), 488; https://doi.org/10.3390/nano10030488 - 8 Mar 2020

Cited by 59 | Viewed by 4310

Abstract

A simple metamaterial absorber is proposed to achieve near-perfect absorption in visible and near-infrared wavelengths. The absorber is composed of metal-dielectric-metal (MIM) three-layer structure. The materials of these three-layer structures are Au, SiO₂, and Au. The top metal structure of the [...] Read more.

A simple metamaterial absorber is proposed to achieve near-perfect absorption in visible and near-infrared wavelengths. The absorber is composed of metal-dielectric-metal (MIM) three-layer structure. The materials of these three-layer structures are Au, SiO₂, and Au. The top metal structure of the absorber is composed of hollow three-dimensional metal rings regularly arranged periodically. The results show that the high absorption efficiency at a specific wavelength is mainly due to the resonance of the Fabry–Perot effect (FP) in the intermediate layer of the dielectric medium, resulting in the resonance light being trapped in the middle layer, thus improving the absorption efficiency. The almost perfect multiband absorption, which is independent of polarization angle and insensitivity of incident angle, lends the absorber great application prospects for filtering and optoelectronics. Full article

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12 pages, 4688 KiB

Open AccessArticle

Perfect Absorption Efficiency Circular Nanodisk Array Integrated with a Reactive Impedance Surface with High Field Enhancement

by Mohamad Khoirul Anam and Sangjo Choi

Nanomaterials 2020, 10(2), 258; https://doi.org/10.3390/nano10020258 - 2 Feb 2020

Cited by 6 | Viewed by 4303

Abstract

Infrared (IR) absorbers based on a metal–insulator–metal (MIM) have been widely investigated due to their high absorption performance and simple structure. However, MIM absorbers based on ultrathin spacers suffer from low field enhancement. In this study, we propose a new MIM absorber structure [...] Read more.

Infrared (IR) absorbers based on a metal–insulator–metal (MIM) have been widely investigated due to their high absorption performance and simple structure. However, MIM absorbers based on ultrathin spacers suffer from low field enhancement. In this study, we propose a new MIM absorber structure to overcome this drawback. The proposed absorber utilizes a reactive impedance surface (RIS) to boost field enhancement without an ultrathin spacer and maintains near-perfect absorption by impedance matching with the vacuum. The RIS is a metallic patch array on a grounded dielectric substrate that can change its surface impedance, unlike conventional metallic reflectors. The final circular nanodisk array mounted on the optimum RIS offers an electric field enhancement factor of 180 with nearly perfect absorption of 98% at 230 THz. The proposed absorber exhibits robust performance even with a change in polarization of the incident wave. The RIS-integrated MIM absorber can be used to enhance the sensitivity of a local surface plasmon resonance (LSPR) sensor and surface-enhanced IR spectroscopy. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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8 pages, 3455 KiB

Open AccessArticle

Ultra-Narrow Band Mid-Infrared Perfect Absorber Based on Hybrid Dielectric Metasurface

by Sai Chen, Zhao Chen, Junku Liu, Jierong Cheng, Yi Zhou, Lin Xiao and Kai Chen

Nanomaterials 2019, 9(10), 1350; https://doi.org/10.3390/nano9101350 - 20 Sep 2019

Cited by 39 | Viewed by 6581

Abstract

Mid-infrared perfect absorbers (PAs) based on metamaterials have many applications in material analysis and spectral detection thanks to the associated strong light–matter interaction. Most of the PAs are built as ‘metal nanostructure’-insulator-metals (MIM). In this paper, we propose an ultra-narrow band absorber based [...] Read more.

Mid-infrared perfect absorbers (PAs) based on metamaterials have many applications in material analysis and spectral detection thanks to the associated strong light–matter interaction. Most of the PAs are built as ‘metal nanostructure’-insulator-metals (MIM). In this paper, we propose an ultra-narrow band absorber based on dielectric metasurface with a metal film substrate. The absorptance comes from the plasmonic absorption in the metal film, where the absorption is enhanced (while the band of that is compressed) by the super cavity effect of the dielectric metasurface. Based on our numerical calculation, the full-width at half-maximum (FWHM) can reach 67 nm at 8 μm (8‰), which is more than two orders of magnitude smaller than the resonance wavelength and much narrower than the theoretical FWHMs of MIM absorbers. Moreover, we studied their application in infrared thermal imaging, which also has more benefits than MIM absorbers. This kind of hybrid dielectric metasurface provides a new route to achieve ultra-narrow band perfect absorbers in the mid-infrared regime and can be broadly applied in detectors, thermal emitters and bio-spectroscopy. Full article

(This article belongs to the Special Issue Nanophotonics and Its Applications)

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8 pages, 1567 KiB

Open AccessArticle

Ultrathin and Electrically Tunable Metamaterial with Nearly Perfect Absorption in Mid-Infrared

by Yuexin Zou, Jun Cao, Xue Gong, Ruijie Qian and Zhenghua An

Appl. Sci. 2019, 9(16), 3358; https://doi.org/10.3390/app9163358 - 15 Aug 2019

Cited by 16 | Viewed by 4486

Abstract

Metamaterials integrated with graphene exhibit tremendous freedom in tailoring their optical properties, particularly in the infrared region, and are desired for a wide range of applications, such as thermal imaging, cloaking, and biosensing. In this article, we numerically and experimentally demonstrate an ultrathin [...] Read more.

Metamaterials integrated with graphene exhibit tremendous freedom in tailoring their optical properties, particularly in the infrared region, and are desired for a wide range of applications, such as thermal imaging, cloaking, and biosensing. In this article, we numerically and experimentally demonstrate an ultrathin (total thickness

< λ_{0} / 15

) and electrically tunable mid-infrared perfect absorber based on metal–insulator–metal (MIM) structured metamaterials. The Q-values of the absorber can be tuned through two rather independent parameters, with geometrical structures of metamaterials tuning radiation loss (Q_r) of the system and the material loss (tanδ) to further change mainly the intrinsic loss (Q_a). This concise mapping of the structural and material properties to resonant mode loss channels enables a two-stage optimization for real applications: geometrical design before fabrication and then electrical tuning as a post-fabrication and fine adjustment knob. As an example, our device demonstrates an electrical and on-site tuning of ~5 dB change in absorption near the perfect absorption region. Our work provides a general guideline for designing and realizing tunable infrared devices and may expand the applications of perfect absorbers for mid-infrared sensors, absorbers, and detectors in extreme spatial-limited circumstances. Full article

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