Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

Article Types

Countries / Regions

Search Results (172)

Search Parameters:
Keywords = THz absorbers

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
14 pages, 2905 KiB  
Article
Optimal Design of a Lightweight Terahertz Absorber Featuring Ultra-Wideband Polarization-Insensitive Characteristics
by Yafeng Hao, Tengteng Li, Pu Zhu, Fupeng Ma, Huijia Wu, Cheng Lei, Meihong Liu, Ting Liang and Jianquan Yao
Photonics 2025, 12(8), 787; https://doi.org/10.3390/photonics12080787 - 4 Aug 2025
Abstract
Metamaterial absorbers in terahertz (THz) based bands have garnered significant attention for their potential applications in military stealth, terahertz imaging, and other fields. Nevertheless, the limited bandwidth, low absorption rate, and heavy weight greatly reduce the further development and wide application of terahertz [...] Read more.
Metamaterial absorbers in terahertz (THz) based bands have garnered significant attention for their potential applications in military stealth, terahertz imaging, and other fields. Nevertheless, the limited bandwidth, low absorption rate, and heavy weight greatly reduce the further development and wide application of terahertz absorbers. To solve these problems, we propose a polystyrene (PS)-based ultra-broadband metamaterial absorber integrated with a polyethylene terephthalate (PET) double-sided adhesive layer and a patterned indium tin oxide (ITO) film through the simulation method, which operates in the THz band. The electromagnetic wave absorption properties and underlying physical absorption mechanisms of the proposed metamaterial absorbers are comprehensively modeled and rigorously numerically simulated. The research demonstrates the metamaterial absorber can achieve absorption performance of over 90% for fully polarized incident waves in the ultra-wideband range of 1.2–10 THz, especially achieving perfect absorption characteristics of over 99.9% near 1.8–1.9 THz and 5.8–6.2 THz. The proposed absorber has a lightweight physical property of 0.7 kg/m2 and polarization-insensitive characteristic, and it achieves a broad-angle that allows a range of incidence angles up to 60°. The simulation research results of this article provide theoretical support for the design of terahertz absorbers with ultra-wideband absorption characteristics. Full article
(This article belongs to the Special Issue Metamaterials and Nanophotonics: Fundamentals and Applications)
Show Figures

Figure 1

13 pages, 3019 KiB  
Article
Efficient Design of a Terahertz Metamaterial Dual-Band Absorber Using Multi-Objective Firefly Algorithm Based on a Multi-Cooperative Strategy
by Guilin Li, Yan Huang, Yurong Wang, Weiwei Qu, Hu Deng and Liping Shang
Photonics 2025, 12(7), 637; https://doi.org/10.3390/photonics12070637 - 24 Jun 2025
Viewed by 340
Abstract
Terahertz metamaterial dual-band absorbers are used for multi-target detection and high-sensitivity sensing in complex environments by enhancing information that reflects differences in the measured substances. Traditional design processes are complex and time-consuming. Machine learning-based methods, such as neural networks and deep learning, require [...] Read more.
Terahertz metamaterial dual-band absorbers are used for multi-target detection and high-sensitivity sensing in complex environments by enhancing information that reflects differences in the measured substances. Traditional design processes are complex and time-consuming. Machine learning-based methods, such as neural networks and deep learning, require a large number of simulations to gather training samples. Existing design methods based on single-objective optimization often result in uneven multi-objective optimization, which restricts practical applications. In this study, we developed a metamaterial absorber featuring a circular split-ring resonator with four gaps nested in a “卍” structure and used the Multi-Objective Firefly Algorithm based on Multiple Cooperative Strategies to achieve fast optimization of the absorber’s structural parameters. A comparison revealed that our approach requires fewer iterations than the Multi-Objective Particle Swarm Optimization and reduces design time by nearly half. The absorber designed using this method exhibited two resonant peaks at 0.607 THz and 0.936 THz, with absorptivity exceeding 99%, indicating near-perfect absorption and quality factors of 31.42 and 30.08, respectively. Additionally, we validated the absorber’s wave-absorbing mechanism by applying impedance-matching theory. Finally, we elucidated the resonance-peak formation mechanism of the absorber based on the surface current and electric-field distribution at the resonance frequencies. These results confirmed that the proposed dual-band metamaterial absorber design is efficient, representing a significant step toward the development of metamaterial devices. Full article
(This article belongs to the Special Issue Thermal Radiation and Micro-/Nanophotonics)
Show Figures

Figure 1

14 pages, 6727 KiB  
Communication
Thermally Tunable Bi-Functional Metasurface Based on InSb for Terahertz Applications
by Rafael Charca-Benavente, Rupesh Kumar, Ruth Rubio-Noriega and Mark Clemente-Arenas
Materials 2025, 18(12), 2847; https://doi.org/10.3390/ma18122847 - 17 Jun 2025
Viewed by 342
Abstract
In this work, we propose and analyze a thermally tunable metasurface based on indium antimonide (InSb), designed to operate in the terahertz (THz) frequency range. The metasurface exhibits dual functionalities: single-band perfect absorption and efficient polarization conversion, enabled by the temperature-dependent permittivity of [...] Read more.
In this work, we propose and analyze a thermally tunable metasurface based on indium antimonide (InSb), designed to operate in the terahertz (THz) frequency range. The metasurface exhibits dual functionalities: single-band perfect absorption and efficient polarization conversion, enabled by the temperature-dependent permittivity of InSb. At approximately 280 K, InSb transitions into a metallic state, enabling the metasurface to achieve near-unity absorptance (100%) at 0.408 THz under normal incidence, independent of polarization. Conversely, when InSb behaves as a dielectric at 200 K, the metasurface operates as an efficient polarization converter. By exploiting structural anisotropy, it achieves a polarization conversion ratio exceeding 85% over the frequency range from 0.56 to 0.93 THz, while maintaining stable performance for incident angles up to 45°. Parametric analyses show that the resonance frequency and absorption intensity can be effectively tuned by varying the InSb square size and the silica (SiO2) layer thickness, achieving maximum absorptance at a SiO2 thickness of 16 μm. The proposed tunable metasurface offers significant potential for applications in THz sensing, imaging, filtering, and wavefront engineering. Full article
(This article belongs to the Special Issue Metamaterials and Metasurfaces: From Materials to Applications)
Show Figures

Figure 1

22 pages, 18692 KiB  
Article
An Improved CNN-Based Algorithm for Quantitative Prediction of Impact Damage Depth in Civil Aircraft Composites via Multi-Domain Terahertz Spectroscopy
by Huazhong Zhang, Hongbiao Yin, Xia Lei, Xiaoqing Xing, Mian Zhong, Rong Yang, Zeguo Liu, Shouqing Li and Zhenguang Mo
Electronics 2025, 14(12), 2412; https://doi.org/10.3390/electronics14122412 - 12 Jun 2025
Viewed by 500
Abstract
To address the issue of low accuracy and stability in traditional Convolutional Neural Networks (CNN)-based defect depth prediction for civil aircraft composites, we propose an improved Feature Enhancement Network (FEN)-CNN-Bidirectional Long Short-Term Memory (BiLSTM) impact damage depth prediction method. By integrating terahertz (THz) [...] Read more.
To address the issue of low accuracy and stability in traditional Convolutional Neural Networks (CNN)-based defect depth prediction for civil aircraft composites, we propose an improved Feature Enhancement Network (FEN)-CNN-Bidirectional Long Short-Term Memory (BiLSTM) impact damage depth prediction method. By integrating terahertz (THz) time-domain, frequency-domain, and absorbance spectroscopy with Confocal Laser Scanning Microscopy (CLSM) depth measurements, the correlation between THz spectral features and impact damage defect depth is systematically elucidated, thereby constructing a “THz features-depth” dataset. Furthermore, by leveraging the FEN model’s feature enhancement and denoising capabilities, along with the BiLSTM model’s bidirectional sequence modeling capability, the underlying relationship between terahertz spectral features and defect depth is deeply learned. This approach improves the stability and accuracy of spectral feature extraction by the CNN model under complex conditions. Ablation experiments revealed the improved model, compared to traditional CNN, reduced Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), Mean Squared Error (MSE), and Root Mean Squared Error (RMSE) by 43.08%, 44.4%, 57.18%, and 34.56%, respectively. Additionally, it decreased the Relative Standard Deviation (RSD) by 32.14%, and increased the Coefficient of Determination (R2) by 6.8%. Comparative experiments demonstrated the proposed model achieved an MSE of 0.0075 and an R2 of 0.9539, outperforming other models. This study provides a novel method for precise low-velocity impact damage assessment in carbon fiber reinforced composites, enhancing safety evaluation for civil aircraft composite structures and contributing to aviation safety. Full article
(This article belongs to the Special Issue Terahertz Optics and Spectroscopy)
Show Figures

Figure 1

15 pages, 3526 KiB  
Article
Simple and Cost-Effective Design of a THz-Metamaterial-Based Hybrid Sensor on a Single Substrate
by Uddipan Nath, Sagnik Banerjee, Carlo Santini, Rocco Citroni, Fabio Mangini and Fabrizio Frezza
Sensors 2025, 25(12), 3660; https://doi.org/10.3390/s25123660 - 11 Jun 2025
Viewed by 426
Abstract
This study presents a cost-effective Hybrid Metamaterial Absorber (HMA) featuring a simple circular-patterned cylindrical design, comprising an indium antimonide (InSb) resonator on a thin copper sheet. Through numerical simulations, we demonstrate that the structure exhibits temperature-tunable properties and refractive index sensitivity. At 300 [...] Read more.
This study presents a cost-effective Hybrid Metamaterial Absorber (HMA) featuring a simple circular-patterned cylindrical design, comprising an indium antimonide (InSb) resonator on a thin copper sheet. Through numerical simulations, we demonstrate that the structure exhibits temperature-tunable properties and refractive index sensitivity. At 300 K (refractive index = 1), a peak absorption of 99.94% is achieved at 1.797 THz. Efficient operation is observed across a 40 K temperature range and a refractive index spectrum of 1.00–1.05, relevant for thermal imaging and spatial bio-sensing. The simulated temperature sensing sensitivity is 13.07 GHz/K, and the refractive index sensitivity is 1146 GHz/RIU. Parametric analyses reveal tunable absorption through adjustments of the InSb resonator design parameters. Owing to its high efficiency and sensitivity demonstrated in simulations, this HMA shows promise for sensing applications in biotechnology, semiconductor fabrication, and energy harvesting. Full article
(This article belongs to the Section Sensor Materials)
Show Figures

Figure 1

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

16 pages, 2210 KiB  
Article
A Highly Sensitive Graphene-Based Terahertz Perfect Absorber Featuring Five Tunable Absorption Peaks
by Hongyu Ma, Pengcheng Shi and Zao Yi
Materials 2025, 18(11), 2601; https://doi.org/10.3390/ma18112601 - 3 Jun 2025
Viewed by 557
Abstract
In this article, we present a high-sensitivity narrow-band perfect graphene absorber that exhibits excellent tunability across multiple bands. The top layer of the absorber unit is composed of graphene material, and the shape is a square graphene layer with a ring structure and [...] Read more.
In this article, we present a high-sensitivity narrow-band perfect graphene absorber that exhibits excellent tunability across multiple bands. The top layer of the absorber unit is composed of graphene material, and the shape is a square graphene layer with a ring structure and a square structure removed from the middle. A SiO2 dielectric layer is located in the middle, and a layer of gold substrate exists at the bottom. This structure has generated five perfect absorption peaks at 6.08216 THz, 7.29058 THz, 9.34669 THz, 11.5471 THz, and 13.0441 THz, and the levels of absorption are 98.24%, 98.03%, 99.55%, 98.87%, and 99.99%, respectively. We have proved the advantages of our model by comparing the influence of different shapes of graphene on the absorption rate of the model. Then, we changed the relaxation time and Fermi energy level of graphene and other factors such as the refractive index to prove that our structure has good tunable performance. Finally, we calculated the sensitivity, and the sensitivity of this structure is as high as 4508.75 GHZ/RIU. Compared with previous articles, our article has more absorption peaks, a higher absorption efficiency, and a higher sensitivity. The absorber proposed in this paper shows great potential to contribute to high-sensitivity sensors, photoelectric detection, photoelectric communication, and other related fields. Full article
Show Figures

Figure 1

13 pages, 1543 KiB  
Article
Switchable Tri-Functional Terahertz Metamaterial Integrated with Vanadium Dioxide and Photosensitive Silicon
by Gui Jin, Ying Zhu, Haorui Yang and Bin Tang
Nanomaterials 2025, 15(11), 835; https://doi.org/10.3390/nano15110835 - 30 May 2025
Viewed by 384
Abstract
This work presents a theoretical and numerical investigation of a switchable tri-functional terahertz metamaterial incorporating vanadium dioxide (VO2) and photosensitive silicon. The selective absorption, broadband linear-to-linear polarization conversion, and dual-band asymmetric transmission (AT) can be realized by utilizing the phase transition [...] Read more.
This work presents a theoretical and numerical investigation of a switchable tri-functional terahertz metamaterial incorporating vanadium dioxide (VO2) and photosensitive silicon. The selective absorption, broadband linear-to-linear polarization conversion, and dual-band asymmetric transmission (AT) can be realized by utilizing the phase transition characteristic of VO2. When VO2 behaves as a metal, the proposed metamaterial functions as a selective perfect absorber for x-polarized waves at 2.84 THz, while exhibiting near-zero absorption for y-polarized waves. When VO2 is in its insulating state, the proposed metamaterial acts as a linear polarization converter, achieving a polarization conversion ratio exceeding 99% within the frequency range of 1.07 to 4.29 THz. Meanwhile, a dual-band AT effect can be simultaneously realized associated with the broadband near-perfect polarization conversion. Furthermore, the polarization conversion efficiency and AT can be actively modulated by adjusting the conductivity of the photosensitive silicon, offering a novel approach for realizing multifunctional terahertz devices. Full article
(This article belongs to the Section Nanophotonics Materials and Devices)
Show Figures

Figure 1

18 pages, 5060 KiB  
Article
Highly Sensitive and Tunable Graphene Metamaterial Perfect Absorber in the Near-Terahertz Band
by Siwen Zhang, Kele Chen, Tangyou Sun, Qianju Song, Zao Yi and Yougen Yi
Coatings 2025, 15(5), 512; https://doi.org/10.3390/coatings15050512 - 24 Apr 2025
Viewed by 692
Abstract
This paper presents a highly sensitive and tunable graphene-based metamaterial perfect absorber (MPA) operating in the near-terahertz band. The structure features a unique flower-like graphene pattern, consisting of a Au substrate, a SiO2 dielectric layer, and the patterned graphene. Multiple reflections of [...] Read more.
This paper presents a highly sensitive and tunable graphene-based metamaterial perfect absorber (MPA) operating in the near-terahertz band. The structure features a unique flower-like graphene pattern, consisting of a Au substrate, a SiO2 dielectric layer, and the patterned graphene. Multiple reflections of incident light between the gold and graphene layers increase the duration and intensity of the interaction, resulting in efficient absorption at specific frequencies. The design utilizes surface plasmon resonance (SPR) to achieve near-perfect absorption of 99.9947% and 99.6079% at 11.7475 THz and 15.8196 THz, respectively. By tuning the Fermi level and relaxation time of graphene, it is possible to precisely control the frequency and absorptivity of the absorption peak, thereby demonstrating the dynamic tunability of the absorber. The high symmetry and periodic arrangement of the structure ensures insensitivity to the polarization angle of the incident light in the range of 0° to 90°, making it extremely valuable in practical applications. In addition, the absorber exhibits very high sensitivity to changes in ambient refractive index with a maximum sensitivity of 3.205 THz/RIU, a quality factor (FOM) of 11.3011 RIU−1, and a Q-Factor of 48.61. It has broad application prospects in the fields of sensors, optoelectronic devices, and terahertz imaging. Full article
(This article belongs to the Section Thin Films)
Show Figures

Figure 1

19 pages, 8785 KiB  
Article
Novel 177Lu-Labeled [Thz14]Bombesin(6–14) Derivatives with Low Pancreas Accumulation for Targeting Gastrin-Releasing Peptide Receptor-Expressing Cancer
by Lei Wang, Devon E. Chapple, Hsiou-Ting Kuo, Sara Kurkowska, Ryan P. Wilson, Wing Sum Lau, Pauline Ng, Carlos Uribe, François Bénard and Kuo-Shyan Lin
Pharmaceuticals 2025, 18(4), 449; https://doi.org/10.3390/ph18040449 - 23 Mar 2025
Viewed by 663
Abstract
Background/Objectives: Gastrin-releasing peptide receptor is a promising target for cancer diagnosis and therapy. However, the high pancreas uptake of reported GRPR-targeted radioligands limits their clinical applications. Our group previously reported one 68Ga-labeled GRPR antagonist, [68Ga]Ga-TacsBOMB5 (68Ga-DOTA-Pip-[D-Phe6,NMe-Gly [...] Read more.
Background/Objectives: Gastrin-releasing peptide receptor is a promising target for cancer diagnosis and therapy. However, the high pancreas uptake of reported GRPR-targeted radioligands limits their clinical applications. Our group previously reported one 68Ga-labeled GRPR antagonist, [68Ga]Ga-TacsBOMB5 (68Ga-DOTA-Pip-[D-Phe6,NMe-Gly11,Leu13ψThz14]Bombesin(6–14)), and two agonists, [68Ga]Ga-LW01110 (68Ga-DOTA-Pip-[D-Phe6,Tle10,NMe-His12,Thz14]Bombesin(6–14)) and [68Ga]Ga-LW01142 (68Ga-DOTA-Pip-[D-Phe6,His7,Tle10,NMe-His12,Thz14]Bombesin(6–14)) showing minimal pancreas uptake. Thus, in this study, we prepared their 177Lu-labeled analogs, evaluated their therapeutic potentials, and compared them with the clinically evaluated [177Lu]Lu-AMBA. Methods: GRPR binding affinities were determined by in vitro competition binding assay using PC-3 prostate cancer cells. Longitudinal SPECT/CT imaging and ex vivo biodistribution studies were conducted in PC-3 tumor-bearing mice. Dosimetry data were calculated from the biodistribution results. Results: The Ki(GRPR) values of Lu-TacsBOMB5, Lu-LW01110, Lu-LW01142, and Lu-AMBA were 12.6 ± 1.02, 3.07 ± 0.15, 2.37 ± 0.28, and 0.33 ± 0.16 nM, respectively. SPECT/CT images and biodistribution results demonstrated good tumor accumulation of [177Lu]Lu-TacsBOMB5, [177Lu]Lu-LW01110, and [177Lu]Lu-LW01142 at early time points with rapid clearance over time. The pancreas uptake of all three [Thz14]Bombesin(6–14)-derived ligands was significantly lower than that of [177Lu]Lu-AMBA at all time points. The calculated absorbed doses of [177Lu]Lu-TacsBOMB5, [177Lu]Lu-LW01110, and [177Lu]Lu-LW01142 in PC-3 tumor xenografts were 87.1, 312, and 312 mGy/MBq, respectively, higher than that of [177Lu]Lu-AMBA (79.1 mGy/MBq), but lower than that of the previously reported [177Lu]Lu-RM2 (429 mGy/MBq). Conclusions: Our data suggest that [177Lu]Lu-TacsBOMB5 and [177Lu]Lu-LW01142 reduce radiation exposure to the pancreas. However, further optimizations are needed for both radioligands to prolong their tumor retention and enhance treatment efficacy. Full article
Show Figures

Figure 1

12 pages, 8103 KiB  
Article
A Thermally Controlled Ultra-Wideband Wide Incident Angle Metamaterial Absorber with Switchable Transmission at the THz Band
by Liansheng Wang, Fengkai Xin, Quanhong Fu and Dongyan Xia
Nanomaterials 2025, 15(5), 404; https://doi.org/10.3390/nano15050404 - 6 Mar 2025
Cited by 1 | Viewed by 737
Abstract
We demonstrate a thermally controlled ultra-wideband wide incident angle metamaterial absorber with switchable transmission at the THz band in this paper. The underlying hybrid structure of FSS-VO2 thin films make them switchable between absorption mode and transmission mode by controlling the temperature. [...] Read more.
We demonstrate a thermally controlled ultra-wideband wide incident angle metamaterial absorber with switchable transmission at the THz band in this paper. The underlying hybrid structure of FSS-VO2 thin films make them switchable between absorption mode and transmission mode by controlling the temperature. It can achieve ultra-wideband absorption with above 90% absorption from 1 THz to 10 THz and exhibits excellent absorption performance under a wide range of incident and polarization angles at a high temperature (80 °C). At room temperature (27 °C), it acts in transmission mode with a transmission coefficient of up to 60% at 3.1278 THz. The transmission region is inside the absorption band, which is very important for practical applications. The metamaterial absorber has the advantage of easy fabrication, an ultra-wideband, a wide incident angle, switchable multi-functions, and passivity with wide application prospects on terahertz communication and radar devices. Full article
Show Figures

Figure 1

23 pages, 6083 KiB  
Article
Switchable and Tunable Terahertz Metamaterial Absorber with Ultra-Broadband and Multi-Band Response for Cancer Detection
by Yadgar I. Abdulkarim
Sensors 2025, 25(5), 1463; https://doi.org/10.3390/s25051463 - 27 Feb 2025
Cited by 5 | Viewed by 1584
Abstract
This paper proposes a switchable and tunable terahertz metamaterial absorber utilizing a graphene-VO2 layered structure. The design employs reconfigurable seven-layer architecture from top to bottom as (topaz/VO2/topaz/Si/graphene/topaz/Au). CST software 2018 was used to simulate the absorption properties of terahertz waves [...] Read more.
This paper proposes a switchable and tunable terahertz metamaterial absorber utilizing a graphene-VO2 layered structure. The design employs reconfigurable seven-layer architecture from top to bottom as (topaz/VO2/topaz/Si/graphene/topaz/Au). CST software 2018 was used to simulate the absorption properties of terahertz waves (0–14 THz). The proposed metamaterial exhibits dual functionalities depending on the VO2 phase state. In the insulating state, the design achieves a tri-band response with distinct peaks at 3.12 THz, 5.65 THz, and 7.24 THz. Conversely, the VO2’s conducting state enables ultra-broadband absorption from 2.52 THz to 11.62 THz. Extensive simulations were conducted to demonstrate the tunability of absorption: Simulated absorption spectra were obtained for broadband and multi-band states. Electric field distributions were analyzed at resonance frequencies for both conducting and insulating states. The impact was studied of VO2 conductivity, loss tangent, and graphene’s chemical potential on absorption. The influence was investigated of topaz layer thickness on the absorption spectrum. Absorption behavior was examined of VO2 under different states and layer configurations. Variations were analyzed of absorption spectra with frequency, polarization angle, and incident angle. The proposed design used for the detection of cervical and breast cancer detection and the sensitivity is about is 0.2489 THz/RIU. The proposed design holds significant promise for real-world applications due to its reconfigurability. This tunability allows for tailoring absorption properties across a broad terahertz range, making it suitable for advanced devices like filters, modulators, and perfect absorbers. Full article
Show Figures

Figure 1

14 pages, 3735 KiB  
Article
Versatile Tunable Terahertz Absorption Device Based on Bulk Dirac Semimetals and Graphene
by Jie Zhou, Xin Sun, Jun Xu, Shiyue Wu, Kaili Jin, Yongjian Tang, Zao Yi and Yougen Yi
Molecules 2025, 30(5), 999; https://doi.org/10.3390/molecules30050999 - 21 Feb 2025
Viewed by 752
Abstract
We employed the CST Microwave Studio software 2020 and the FDID algorithm for simulation. We have designed a terahertz broadband absorber based on Dirac semimetals and graphene, achieving continuous broadband absorption with a rate exceeding 80% over the range from 7.6776 to 9.172 [...] Read more.
We employed the CST Microwave Studio software 2020 and the FDID algorithm for simulation. We have designed a terahertz broadband absorber based on Dirac semimetals and graphene, achieving continuous broadband absorption with a rate exceeding 80% over the range from 7.6776 to 9.172 THz. This broadband absorber features two independent tuning modes, utilizing graphene and Dirac semimetals, and exhibits strong electromagnetic adaptability. Furthermore, we conducted an in-depth analysis of the physical mechanisms underlying the high absorption in these absorbers using impedance matching theory and localized surface plasmon resonance (LSPR) theory. Variations in the dielectric constants of different dielectric layers and the relaxation time of graphene can also modulate the absorption rate. In summary, our proposed terahertz broadband absorber, employing two distinct tunable materials, enhances the device’s flexibility and environmental adaptability, offering promising prospects for wideband absorption applications. Full article
Show Figures

Figure 1

11 pages, 2833 KiB  
Communication
Terahertz Metamaterial Absorber and Equivalent Circuit Model for Refractive Index Sensing
by Zhengxiong Lu, Peixuan Li, Chuanwei Zhang, Shuaitian Li, Ruibo Chen, Ziliang Zhou and Xiaojun Huang
Materials 2025, 18(4), 765; https://doi.org/10.3390/ma18040765 - 10 Feb 2025
Viewed by 1214
Abstract
As a kind of important functional device, terahertz metamaterial absorbers (TMA) have been focused on by many researchers for their capacity to absorb electromagnetic waves and wide application fields. In this work, we designed a terahertz metamaterial absorber with narrow-band absorption for refractive [...] Read more.
As a kind of important functional device, terahertz metamaterial absorbers (TMA) have been focused on by many researchers for their capacity to absorb electromagnetic waves and wide application fields. In this work, we designed a terahertz metamaterial absorber with narrow-band absorption for refractive index sensing, which consisted of a circular metal ring resonator and a square metal ring resonator. The simulation results show that the absorptivity of the proposed TMA reached over 68.8% and 93.27% at 1.926 and 4.413 THz, respectively. Moreover, the absorption mechanism was studied through the electromagnetic field energy distribution, and the influence of structural parameters on absorption performance was exhibited. In refractive index sensing, a high sensitivity (S) of 2.537 THz/RIU (refractive index unit, RIU) was achieved by utilizing the coupling of ring resonators. The maximal quality factor (Q-factor) and figure of merit (FOM) of the TMA were 234.73 and 147.67 RIU−1, respectively. Additionally, we established an RLC equivalent circuit model (ECM) for the TMA, and we further illustrated the performance of the TMA in refractive index sensing through fitting the sensitivity based on the ECM to the sensitivity of the TMA. Our study exhibits the considerable potential application for the field of terahertz sensing, and the ECM for refractive index sensing will be helpful for continual investigation. Full article
Show Figures

Figure 1

17 pages, 4616 KiB  
Article
All-Metal Metamaterial-Based Sensor with Novel Geometry and Enhanced Sensing Capability at Terahertz Frequency
by Sagnik Banerjee, Ishani Ghosh, Carlo Santini, Fabio Mangini, Rocco Citroni and Fabrizio Frezza
Sensors 2025, 25(2), 507; https://doi.org/10.3390/s25020507 - 16 Jan 2025
Cited by 5 | Viewed by 1559
Abstract
This research proposes an all-metal metamaterial-based absorber with a novel geometry capable of refractive index sensing in the terahertz (THz) range. The structure consists of four concentric diamond-shaped gold resonators on the top of a gold metal plate; the resonators increase in height [...] Read more.
This research proposes an all-metal metamaterial-based absorber with a novel geometry capable of refractive index sensing in the terahertz (THz) range. The structure consists of four concentric diamond-shaped gold resonators on the top of a gold metal plate; the resonators increase in height by 2 µm moving from the outer to the inner resonators, making the design distinctive. This novel configuration has played a very significant role in achieving multiple ultra-narrow resonant absorption peaks that produce very high sensitivity when employed as a refractive index sensor. Numerical simulations demonstrate that it can achieve six significant ultra-narrow absorption peaks within the frequency range of 5 to 8 THz. The sensor has a maximum absorptivity of 99.98% at 6.97 THz. The proposed absorber also produces very high-quality factors at each resonance. The average sensitivity is 7.57/Refractive Index Unit (THz/RIU), which is significantly high when compared to the current state of the art. This high sensitivity is instrumental in detecting smaller traces of samples that have very correlated refractive indices, like several harmful gases. Hence, the proposed metamaterial-based sensor can be used as a potential gas detector at terahertz frequency. Furthermore, the structure proves to be polarization-insensitive and produces a stable absorption response when the angle of incidence is increased up to 60°. At terahertz wavelength, the proposed design can be used for any value of the aforementioned angles, targeting THz spectroscopy-based biomolecular fingerprint detection and energy harvesting applications. Full article
(This article belongs to the Special Issue Recent Advances in THz Sensing and Imaging)
Show Figures

Figure 1

Back to TopTop