scholarly journals Dynamically Tunable Resonant Strength in Electromagnetically Induced Transparency (EIT) Analogue by Hybrid Metal-Graphene Metamaterials

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 171 ◽  
Author(s):  
Chaode Lao ◽  
Yaoyao Liang ◽  
Xianjun Wang ◽  
Haihua Fan ◽  
Faqiang Wang ◽  
...  
Keyword(s):  
Optical Networks ◽  
Electromagnetically Induced Transparency ◽  
Near Field ◽  
Monolayer Graphene ◽  
Dark Mode ◽  
Resonance Strength ◽  
Field Coupling ◽  
Terahertz Communications ◽  
Unit Cells ◽  
Induced Transparency

In this paper, a novel method to realize a dynamically tunable analogue of EIT for the resonance strength rather than the resonance frequency is proposed in the terahertz spectrum. The introduced method is composed of a metal EIT-like structure, in which a distinct EIT phenomenon resulting from the near field coupling between bright and dark mode resonators can be obtained, as well as an integrated monolayer graphene ribbon under the dark mode resonator that can continuously adjust the resonance strength of transparency peak by changing the Fermi level of the graphene. Comparing structures that need to be modulated individually for each unit cell of the metamaterials, the proposed modulation mechanism was convenient for achieving synchronous operations for all unit cells. This work demonstrates a new platform of modulating the EIT analogue and paves the way to design terahertz functional devices which meet the needs of optical networks and terahertz communications.

scholarly journals Experimental Demonstration of Electromagnetically Induced Transparency in a Conductively Coupled Flexible Metamaterial with Cheap Aluminum Foil

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Jie Hu ◽  
Tingting Lang ◽  
Weihang Xu ◽  
Jianjun Liu ◽  
Zhi Hong
Keyword(s):  
Electromagnetically Induced Transparency ◽  
Near Field ◽  
Surface Current ◽  
Aluminum Foil ◽  
Ring Resonators ◽  
Dark Mode ◽  
Field Coupling ◽  
New Ideas ◽  
Induced Transparency ◽  
Bright Mode

AbstractWe propose a conductively coupled terahertz metallic metamaterial exhibiting analog of electromagnetically induced transparency (EIT), in which the bright and dark mode antennae interact via surface currents rather than near-field coupling. Aluminum foil, which is very cheap and often used in food package, is used to fabricate our metamaterials. Thus, our metamaterials are also flexible metamaterials. In our design, aluminum bar resonators and aluminum split ring resonators (SRRs) are connected (rather than separated) in the form of a fork-shaped structure. We conduct a numerical simulation and an experiment to analyze the mechanism of the proposed metamaterial. The surface current due to LSP resonance (bright mode) flows along different paths, and a potential difference is generated at the split gaps of the SRRs. Thus, an LC resonance (dark mode) is induced, and the bright mode is suppressed, resulting in EIT. The EIT-like phenomenon exhibited by the metamaterial is induced by surface conducting currents, which may provide new ideas for the design of EIT metamaterials. Moreover, the process of fabricating microstructures on flexible substrates can provide a reference for producing flexible microstructures in the future.

scholarly journals Analog of multiple electromagnetically induced transparency using double-layered metasurfaces

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Siyuan Liu ◽  
Zhixia Xu ◽  
Xiaoxing Yin ◽  
Hongxin Zhao
Keyword(s):  
Electromagnetically Induced Transparency ◽  
Near Field ◽  
Localized Surface Plasmons ◽  
Dark Mode ◽  
Field Coupling ◽  
Double Peaks ◽  
Resonant Modes ◽  
Physical Essence ◽  
Induced Transparency ◽  
Mode A

Abstract We reported an analog of electromagnetically induced transparency (A-EIT) featured by double transparent peaks in the spectrum. The A-EIT is realized by double-layered metasurface which consists of spoof localized surface plasmons (S-LSP) and cut-wire (CW)-square rings (SR) hybrid. Electric and magnetic S-LSP are excited as bright and dark modes respectively then couple with resonant modes of CW and SR simultaneously to achieve multiple A-EIT. Two bright modes of the electric S-LSP and SR are excited by external electric field directly that produce a bright-bright mode A-EIT. Moreover, the magnetic S-LSP, which cannot be excited by external field directly, is excited through near field coupling from CW, inducing another bright-dark mode A-EIT. Theoretical analysis with corresponding experiment in microwave band are introduced for better insights into physical essence of the double-peaks A-EIT.

scholarly journals Broadband Filter and Adjustable Extinction Ratio Modulator Based on Metal-Graphene Hybrid Metamaterials

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1359 ◽  
Author(s):  
Haoying Sun ◽  
Lin Zhao ◽  
Jinsong Dai ◽  
Yaoyao Liang ◽  
Jianping Guo ◽  
...  
Keyword(s):  
Electromagnetically Induced Transparency ◽  
Extinction Ratio ◽  
Optical Filters ◽  
Superior Performance ◽  
Dark Mode ◽  
Terahertz Communications ◽  
Transmission Window ◽  
Induced Transparency ◽  
Bright Mode ◽  
Mode Resonator

A novel multifunctional device based on a hybrid metal–graphene Electromagnetically induced transparency (EIT) metamaterial at the terahertz band is proposed. It is composed of a parallel cut wire pair (PCWP) that serves as a dark mode resonator, a vertical cut wire pair (VCWP) that serves as a bright mode resonator and a graphene ribbon that serves as a modulator. An ultra-broadband transmission window with 1.23 THz bandwidth can be obtained. The spectral extinction ratio can be tuned from 26% to 98% by changing the Fermi level of the graphene. Compared with previous work, our work has superior performance in the adjustable bandwidth of the transmission window without changing the structure of the dark and bright mode resonators, and has a high extinction ratio and dynamic adjustability. Besides, we present the specific application of the device in filters and optical modules. Therefore, we believe that such a metamaterial structure provides a new way to actively control EIT-like, which has promising applications in broadband optical filters and photoelectric intensity modulators in terahertz communications.

scholarly journals Asymmetric excitation of surface plasmons by dark mode coupling

2016 ◽  
Vol 2 (2) ◽  
pp. e1501142 ◽  
Author(s):  
Xueqian Zhang ◽  
Quan Xu ◽  
Quan Li ◽  
Yuehong Xu ◽  
Jianqiang Gu ◽  
...  
Keyword(s):  
Surface Plasmons ◽  
Mode Coupling ◽  
Electromagnetic Waves ◽  
Electromagnetically Induced Transparency ◽  
Near Field ◽  
Coupling Mechanism ◽  
Dark Mode ◽  
Resolution Imaging ◽  
Experimental Findings ◽  
Induced Transparency

Control over surface plasmons (SPs) is essential in a variety of cutting-edge applications, such as highly integrated photonic signal processing systems, deep-subwavelength lasing, high-resolution imaging, and ultrasensitive biomedical detection. Recently, asymmetric excitation of SPs has attracted enormous interest. In free space, the analog of electromagnetically induced transparency (EIT) in metamaterials has been widely investigated to uniquely manipulate the electromagnetic waves. In the near field, we show that the dark mode coupling mechanism of the classical EIT effect enables an exotic and straightforward excitation of SPs in a metasurface system. This leads to not only resonant excitation of asymmetric SPs but also controllable exotic SP focusing by the use of the Huygens-Fresnel principle. Our experimental findings manifest the potential of developing plasmonic metadevices with unique functionalities.

scholarly journals 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 ◽  
Vol 11 (2) ◽  
pp. 164 ◽  
Author(s):  
Man Hoai Nam ◽  
Vu Thi Hong Hanh ◽  
Nguyen Ba Tuong ◽  
Bui Son Tung ◽  
Bui Xuan Khuyen ◽  
...  
Keyword(s):  
Time Delay ◽  
Dispersion Characteristic ◽  
Electromagnetically Induced Transparency ◽  
Near Field ◽  
Group Index ◽  
High Group ◽  
Split Ring ◽  
Field Coupling ◽  
Induced Transparency ◽  
Multi Band

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.

scholarly journals Graphene-Modulated Terahertz Metasurfaces for Selective and Active Control of Dual-Band Electromagnetic Induced Reflection (EIR) Windows

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2420
Author(s):  
Xunjun He ◽  
Chenguang Sun ◽  
Yue Wang ◽  
Guangjun Lu ◽  
Jiuxing Jiang ◽  
...  
Keyword(s):  
Active Control ◽  
Slow Light ◽  
Near Field ◽  
Dual Band ◽  
Destructive Interference ◽  
Dark Mode ◽  
Field Coupling ◽  
Control Scheme ◽  
Electrostatic Doping ◽  
Induced Transparency

Currently, metasurfaces (MSs) integrating with different active materials have been widely explored to actively manipulate the resonance intensity of multi-band electromagnetic induced transparency (EIT) windows. Unfortunately, these hybrid MSs can only realize the global control of multi-EIT windows rather than selective control. Here, a graphene-functionalized complementary terahertz MS, composed of a dipole slot and two graphene-integrated quadrupole slots with different sizes, is proposed to execute selective and active control of dual-band electromagnetic induced reflection (EIR) windows. In this structure, dual-band EIR windows arise from the destructive interference caused by the near field coupling between the bright dipole slot and dark quadrupole slot. By embedding graphene ribbons beneath two quadrupole slots, the resonance intensity of two windows can be selectively and actively modulated by adjusting Fermi energy of the corresponding graphene ribbons via electrostatic doping. The theoretical model and field distributions demonstrate that the active tuning behavior can be ascribed to the change in the damper factor of the corresponding dark mode. In addition, the active control of the group delay is further investigated to develop compact slow light devices. Therefore, the selective and active control scheme introduced here can offer new opportunities and platforms for designing multifunctional terahertz devices.

scholarly journals Analogue of Electromagnetically Induced Transparency in an All-Dielectric Double-Layer Metasurface Based on Bound States in the Continuum

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2343
Author(s):  
Fengyan He ◽  
Jianjun Liu ◽  
Guiming Pan ◽  
Fangzhou Shu ◽  
Xufeng Jing ◽  
...  
Keyword(s):  
Double Layer ◽  
Bound States ◽  
Electromagnetically Induced Transparency ◽  
Near Field ◽  
Relative Displacement ◽  
Photonic Devices ◽  
Field Coupling ◽  
Potential Applications ◽  
Induced Transparency ◽  
The Continuum

Bound states in the continuum (BICs) have attracted much attention due to their infinite Q factor. However, the realization of the analogue of electromagnetically induced transparency (EIT) by near-field coupling with a dark BIC in metasurfaces remains challenging. Here, we propose and numerically demonstrate the realization of a high-quality factor EIT by the coupling of a bright electric dipole resonance and a dark toroidal dipole BIC in an all-dielectric double-layer metasurface. Thanks to the designed unique one-dimensional (D)–two-dimensional (2D) combination of the double-layer metasurface, the sensitivity of the EIT to the relative displacement between the two layer-structures is greatly reduced. Moreover, several designs for widely tunable EIT are proposed and discussed. We believe the proposed double-layer metasurface opens a new avenue for implementing BIC-based EIT with potential applications in filtering, sensing and other photonic devices.

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