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Huang Y, Kida T, Wakiuchi S, Okatani T, Inomata N, Kanamori Y. 3D Bulk Metamaterials with Engineered Optical Dispersion at Terahertz Frequencies Utilizing Amorphous Multilayered Split-Ring Resonators. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2405378. [PMID: 38976553 PMCID: PMC11425637 DOI: 10.1002/advs.202405378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 06/25/2024] [Indexed: 07/10/2024]
Abstract
A 3D bulk metamaterial (MM) containing amorphous multilayered split-ring resonators is proposed, fabricated, and evaluated. Experimentally, the effective refractive index is engineered via the 3D bulk MM, with a contrast of 0.118 across the frequency span from 0.315 to 0.366 THz and the index changing at a slope of 2.314 per THz within this frequency range. Additionally, the 3D bulk MM exhibits optical isotropy with respect to polarization. Moreover, the peak transmission and optical dispersion are tailored by adjusting the density of the split-ring resonators. Compared to reported conventional approaches for constructing bulk MMs, this approach offers advantages in terms of the potential for large-scale manufacturing, the ability to adopt any shape, optical isotropy, and rapid optical dispersion. These features hold promise for dispersive optical devices operating at THz frequencies, such as high-dispersive prisms for high-resolution spectroscopy.
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Affiliation(s)
- Ying Huang
- Department of RoboticsTohoku UniversitySendaiMiyagi980‐8579Japan
| | - Takanori Kida
- Department of RoboticsTohoku UniversitySendaiMiyagi980‐8579Japan
| | - Shun Wakiuchi
- Department of RoboticsTohoku UniversitySendaiMiyagi980‐8579Japan
| | - Taiyu Okatani
- Department of RoboticsTohoku UniversitySendaiMiyagi980‐8579Japan
| | - Naoki Inomata
- Department of RoboticsTohoku UniversitySendaiMiyagi980‐8579Japan
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Okatani T, Dashdeleg MO, Inomata N, Kanamori Y. Terahertz stretchable metamaterials with deformable dolmen resonators for uniaxial strain measurement. OPTICS EXPRESS 2024; 32:12024-12039. [PMID: 38571037 DOI: 10.1364/oe.514848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/08/2024] [Indexed: 04/05/2024]
Abstract
In this study, we propose a terahertz stretchable metamaterial that can measure uniaxial strain. Gold dolmen resonators formed on a sheet of polydimethylsiloxane (PDMS) is deformed by strain, and its resonance peak exhibits the gradual decrease in reflectance without a frequency shift, which is suitable for imaging applications at a single frequency. The metamaterial was designed by mechanical and electromagnetic simulations and fabricated by microfabrication including a transfer process of gold structures from a glass substrate to a PDMS sheet. By measuring the reflectance and observing the deformation under different strains, the reflectance decrease was obtained at 0.292 THz despite the appearance of wrinkles on gold structures. Linear response and repeatability up to 20% strain were also confirmed. Furthermore, the strain measurement through a sheet of paper was demonstrated, suggesting that our method can be applied even in situations where opaque obstacles in the visible region exist.
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Van Nguyen M, Okatani T, Kanamori Y. Fabrication of functional metamaterials for applications in heat-shielding windows and 6G communications. APPLIED OPTICS 2023; 62:7411-7419. [PMID: 37855509 DOI: 10.1364/ao.497886] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 09/10/2023] [Indexed: 10/20/2023]
Abstract
Windows with passive multilayer coatings can allow less energy to be used when maintaining comfortable indoor temperatures. As a type of effective solar energy management, these coatings can prevent the generation of excessive heat inside buildings or vehicles by reflecting near-infrared solar radiation (750-2000 nm) while retaining visible light transmission (400-750 nm) over a large range of viewing angles. To prevent overheating, they must also reflect rather than absorb near-infrared radiation. A transparent heat-shielding window is numerically and experimentally demonstrated in this study. High visual transparency (77.2%), near-infrared reflectance (86.1%), and low infrared absorption (<20%) over a wide range of oblique incident angles were achieved using nanometer-scale cross-shaped metamaterials manufactured by electron beam lithography. Furthermore, high terahertz transmittance (up to 82%) was also achieved for 6G communication system applications.
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Huang Y, Okatani T, Inomata N, Kanamori Y. Reconfigurable THz metamaterial based on microelectromechanical cantilever switches with a dimpled tip. OPTICS EXPRESS 2023; 31:29744-29754. [PMID: 37710768 DOI: 10.1364/oe.497514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 08/03/2023] [Indexed: 09/16/2023]
Abstract
We numerically and experimentally proposed a reconfigurable THz metamaterial (MM) by employing microelectromechanical cantilevers into a ladder-shaped MM (LS-MM). A fixed-free cantilever array with a dimpled tip behaved as Ohmic switches to reshape the LS-MM so as to actively regular the transmission response of THz waves. The cantilever tip was designed to be a concave dimple to improve the operational life without sacrificing the mechanical resonant frequency (fmr), and a fmr of 635 kHz was demonstrated. The device actively achieved a 115-GHz change in transmittance resonant frequency and a 1.82-rad difference in transmission phase shift, which can practically benefit advancing THz applications such as fast THz imaging and 6 G communications.
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Wu Z, Liu P, Lin M, Zha S, Ni X. A Microwave Field-Induced Nonlinear Metamaterial with Wafer Integration Level. ACS APPLIED MATERIALS & INTERFACES 2023; 15:16189-16197. [PMID: 36921290 DOI: 10.1021/acsami.2c21964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Field-induced nonlinear materials, with extended abilities of manipulating electromagnetic waves, have been widely employed in electromagnetic protection, absorption, and detection. Until now, it was found that the field-induced nonlinearity mainly shows in the optical and terahertz frequency bands. Applying the microwave band into such technical activities is hampered due to a lack of investigations on the nonlinearity caused by microwave electric fields, especially in the ultrawideband and microwave high-frequency bands. In this paper, a nonlinear metamaterial (NLMM) concept based on the integration of metamaterial structures and a semiconductor on the same wafer is proposed, which shows nonlinear behavior to the electromagnetics' field energy in the microwave band. The designed NLMM is transparent to low-density electromagnetic radiation fields, while it adaptively becomes opaque to high-density electromagnetic radiation fields. Two types of NLMM are designed to verify the nonlinear characteristics of ultrawide and narrow bands in the microwave band, respectively. The concept of NLMM can be used for the application of the microwave frequency band in electromagnetic protection and detection.
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Affiliation(s)
- Zhaofeng Wu
- College of Electronic Science, National University of Defense Technology, Changsha 410073, China
| | - Peiguo Liu
- College of Electronic Science, National University of Defense Technology, Changsha 410073, China
| | - Mingtuan Lin
- College of Electronic Science, National University of Defense Technology, Changsha 410073, China
| | - Song Zha
- College of Electronic Science, National University of Defense Technology, Changsha 410073, China
| | - Xiaocheng Ni
- College of Electronic Science, National University of Defense Technology, Changsha 410073, China
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Zhang Z, Gao D, Si J, Meng J. Classical Analog and Hybrid Metamaterials of Tunable Multiple-Band Electromagnetic Induced Transparency. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:4405. [PMID: 36558255 PMCID: PMC9781127 DOI: 10.3390/nano12244405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/05/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
The electromagnetic induced transparency (EIT) effect originates from the destructive interference in an atomic system, which contributes to the transparency window in its response spectrum. The implementation of EIT requires highly demanding laboratory conditions, which greatly limits its acceptance and application. In this paper, an improved harmonic spring oscillation (HSO) model with four oscillators is proposed as a classical analog for the tunable triple-band EIT effect. A more general HSO model including more oscillators is also given, and the analyses of the power absorption in the HSO model conclude a formula, which is more innovative and useful for the study of the multiple-band EIT effect. To further inspect the analogizing ability of the HSO model, a hybrid unit cell containing an electric dipole and toroidal dipoles in the metamaterials is proposed. The highly comparable transmission spectra based on the HSO model and metamaterials indicate the validity of the classical analog in illustrating the formation process of the multiple-band EIT effect in metamaterials. Hence, the HSO model, as a classical analog, is a valid and powerful theoretical tool that can mimic the multiple-band EIT effect in metamaterials.
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Affiliation(s)
- Zhi Zhang
- State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, China
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Laboratory of Information Photonic Technique, Xi’an Jiaotong University, Xi’an 710049, China;
- School of Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Duorui Gao
- State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, China
- School of Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinhai Si
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Laboratory of Information Photonic Technique, Xi’an Jiaotong University, Xi’an 710049, China;
| | - Jiacheng Meng
- State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, China
- School of Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
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Zhang W, Lin J, Fang X, Lin Y, Wang K, Zhang M. An Active Electromagnetically Induced Transparency (EIT) Metamaterial Based on Conductive Coupling. MATERIALS (BASEL, SWITZERLAND) 2022; 15:7371. [PMID: 36295435 PMCID: PMC9606948 DOI: 10.3390/ma15207371] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/06/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
In this paper, we demonstrate an active metamaterial manifesting electromagnetically induced transparency (EIT) effect in the microwave regime. The metamaterial unit cell consists of a double-cross structure, between which a varactor diode is integrated. The capacitance of the diode is controlled by a reversed electrical bias voltage supplied through two connected strip lines. The diode behaves as a radiative resonant mode and the strip lines as a non-radiative resonant mode. The two modes destructively interference with each other through conductive coupling, which leads to a transmission peak in EIT effect. Through electrical control of the diode capacitance, the transmission peak frequency is shifted from 7.4 GHz to 8.7 GHz, and the peak-to-dip ratio is tuned from 1.02 to 1.66, demonstrating a significant tunability.
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Affiliation(s)
- Wu Zhang
- School of Physics and Material Science, Guangzhou University, Guangzhou 510006, China
| | - Jiahan Lin
- School of Physics and Material Science, Guangzhou University, Guangzhou 510006, China
| | - Xiaohui Fang
- School of Physics and Material Science, Guangzhou University, Guangzhou 510006, China
| | - Yanxiao Lin
- School of Physics and Material Science, Guangzhou University, Guangzhou 510006, China
| | - Kai Wang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Meng Zhang
- School of Electronics and Communication Engineering, Guangzhou University, Guangzhou 510006, China
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Zhang Y, Qiu F, Liang L, Yao H, Yan X, Liu W, Huang C, Yao J. Three-stimulus control ultrasensitive Dirac point modulator using an electromagnetically induced transparency-like terahertz metasurface with graphene. OPTICS EXPRESS 2022; 30:24703-24715. [PMID: 36237018 DOI: 10.1364/oe.465631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 06/15/2022] [Indexed: 06/16/2023]
Abstract
This letter presents a fabricated Dirac point modulator of a graphene-based terahertz electromagnetically induced transparency (EIT)-like metasurface (GrE & MS). Dynamic modulation is realized by applying three stimulus modes of optical pump, bias voltage, and optical pump-bias voltage combination. With increasing luminous flux or bias voltage, the transmission amplitude undergoes two stages: increasing and decreasing, because the graphene Fermi level shifts between the valence band, Dirac point, and conduction band. Thus, an approximate position of the Dirac point can be evaluated by the transmission spectrum fluctuation. The maximum modulation depth is measured to be 182% under 1 V. These findings provide a method for designing ultrasensitive terahertz modulation devices.
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Oh-e M, Zheng DY. Newly discovered dimensional effects of electrodes on liquid crystal THz phase shifters enable novel switching between in-plane and out-of-plane. Sci Rep 2022; 12:5482. [PMID: 35361796 PMCID: PMC8971443 DOI: 10.1038/s41598-022-07832-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/23/2022] [Indexed: 11/09/2022] Open
Abstract
To unveil a novel switching mechanism in liquid crystal (LC)-based phase shifters for the THz range, we analyse how the dimensions of the electrode structures enable a new type of switching, namely, THz in-plane and THz out-of-plane (TIP–TOP) switching. Specifically, we determine how varying these electrode dimensions influences the LC in-plane states with the corresponding phase shifts by calculating these effects in virtual devices. Interestingly, we found that significant dimensional effects of the in-plane electrode structures statically and dynamically influence the phase shift and response time of LC switching. Analysing the electromagnetic fields in the TIP–TOP cell clearly reveals that these dimensional effects are due to changes in the electric field strengths caused by lateral bus-line electrodes that were originally assumed not to contribute to the switching. Further, we discover that the ultimate dimensional effect produces a novel type of LC switching, which results in hexadirectional switching between the initial, intrinsic in-plane, and out-of-plane reorientations of the LCs, suggesting a broader range of phase shifts while maintaining a rapid response.
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Affiliation(s)
- Masahito Oh-e
- Institute of Photonics Technologies, Department of Electrical Engineering, National Tsing Hua University, 101 Sec. 2 Kuang-Fu Road, Hsinchu, 300044, Taiwan.
| | - Deng-Yun Zheng
- Institute of Photonics Technologies, Department of Electrical Engineering, National Tsing Hua University, 101 Sec. 2 Kuang-Fu Road, Hsinchu, 300044, Taiwan
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Bark HS, Park MW, Baek IH, Jang KH, Jeong YU, Lee K, Jeon TI. Broadband terahertz guided-mode resonance filter using cyclic olefin copolymer. OPTICS EXPRESS 2022; 30:7976-7986. [PMID: 35299549 DOI: 10.1364/oe.452064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/13/2022] [Indexed: 06/14/2023]
Abstract
We propose an all-dielectric single-layer guided-mode resonance filter (GMRF) operating in the high-frequency terahertz (THz) region. For the fabrication of thin gratings to achieve strong resonance in the high-frequency region, the refractive index and absorption must be small, while the tensile strength must be high. Cyclic olefin copolymer (COC) films have a lower refractive index and absorption than polyethylene terephthalate (PET) films and a higher tensile yield strength than polytetrafluoroethylene (PTFE) films. Therefore, the COC film was found suitable to fabricate a GMRF operating in the high-frequency THz region. We fabricated COC-based single-layer GMRFs with a thickness of 50 µm and grating periods of 500, 400, 300, 200, and 100 µm; the resonance frequencies of the TE0,1 mode were 0.576, 0.712, 0.939, 1.329, and 2.759 THz, respectively. A shorter grating period caused a greater shift of the resonance to a higher frequency. In particular, the COC film enabled the fabrication of a 100-µm grating period with a ridge width of 32 µm and length of 2 mm, enabling the GMRF to operate up to 2.759 THz, which is very high frequency compared to the previous highest frequency of 0.7 THz. These results were in good agreement with a simulation using rigorous coupled-wave analysis.
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Abstract
In recent years, tunable metamaterials have attracted intensive research interest due to their outstanding characteristics, which are dependent on the geometrical dimensions rather than the material composition of the nanostructure. Among tuning approaches, micro-electro-mechanical systems (MEMS) is a well-known technology that mechanically reconfigures the metamaterial unit cells. In this study, the development of MEMS-based metamaterial is reviewed and analyzed based on several types of actuators, including electrothermal, electrostatic, electromagnetic, and stretching actuation mechanisms. The moveable displacement and driving power are the key factors in evaluating the performance of actuators. Therefore, a comparison of actuating methods is offered as a basic guideline for selecting micro-actuators integrated with metamaterial. Additionally, by exploiting electro-mechanical inputs, MEMS-based metamaterials make possible the manipulation of incident electromagnetic waves, including amplitude, frequency, phase, and the polarization state, which enables many implementations of potential applications in optics. In particular, two typical applications of MEMS-based tunable metamaterials are reviewed, i.e., logic operation and sensing. These integrations of MEMS with metamaterial provide a novel route for the enhancement of conventional optical devices and exhibit great potentials in innovative applications, such as intelligent optical networks, invisibility cloaks, photonic signal processing, and so on.
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Multi-Band Electromagnetically-Induced-Transparency Metamaterial Based on the Near-Field Coupling of Asymmetric Split-Ring and Cut-Wire Resonators in the GHz Regime. CRYSTALS 2021. [DOI: 10.3390/cryst11020164] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A metamaterial (MM), mimicking electromagnetically-induced transparency (EIT) in the GHz regime, was demonstrated numerically and experimentally by exploiting the near-field coupling of asymmetric split-ring and cut-wire resonators. By moving the resonators towards each other, the original resonance dip was transformed to a multi-band EIT. The phenomenon was explained clearly through the excitation of bright and dark modes. The dispersion characteristic of the proposed MM was also investigated, which showed a strongly-dispersive behavior, leading to a high group index and a time delay of the MM. Our work is expected to contribute a simple way to develop the potential devices based on the multi-band EIT effect.
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