- 标题
- 摘要
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- 实验方案
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Electrical Control of Electromagnetically Induced Transparency by Terahertz Metamaterial Funneling
摘要： Electromagnetically induced transparency (EIT) analogs using metamaterials have diverse applications, including nonlinear optics, telecommunications, and biochemical sensors. These EIT analogs can be actively controlled by embedding semiconducting materials into metamaterial structures, but most active EIT metamaterials require complex optical setups and complicated fabrication processes. Graphene-based EIT metamaterials are some of the most promising active EIT systems because of their simple controllability by electrical bias, but related researches have so far been limited to theoretical or numerical studies. Here, experimentally verified graphene EIT metamaterials are provided by controlling the terahertz funneling of the unique metaatom structures. The proposed active EIT metamaterials are fabricated on flexible and ultrathin polyimide films to acquire the lowest substrate insertion losses and achieve a 1 ps group delay change at the transmission peak of the EIT analog. Moreover, because the proposed metamaterials exhibit resonance properties that vary depending on the polarization direction, the phase delay can be controlled up to 80° from the proposed metamaterials by rotating the incident polarization to the orthogonal direction. Overall, by controlling the group and phase delay of incident waves in a single metamaterial device simultaneously, a multifunctional active tuning system can be realized in the terahertz range.
关键词： terahertz,field enhancement,graphene,ion-gel,active metamaterials
更新于2025-09-10 09:29:36
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Improved field emission from appropriately packed TiO2 nanorods: Designing the miniaturization
摘要： An improved electron field emission (FE) property from vertically aligned TiO2 nanorods (TNR) on conducting fluorine doped tin oxide coated glass substrate, prepared by hydrothermal technique, has been reported here. The TNRs having high aspect ratio with appropriate separation were prepared by optimizing the nucleation temperature. The TNR density has been optimized to cease the screening effect in closely packed nanorods. The well aligned rods have been designed so that the applied field is equally distributes on each rod to improve the electron emission. The morphology of the nanorod has been studied using scanning electron microscopy and observed FE current density-field response has been analysed within the frame work of Fowler-Nordheim modelling. Two orders of magnitude enhancement in the electric field has been observed for this kind of geometry giving improved turn on field and field enhancement factor of 0.2 V/m m and 37 thousands respectively.
关键词： Fowler-Nordheim modelling,Hydrothermal technique,Field emission,TiO2 nanorods,Field enhancement factor
更新于2025-09-09 09:28:46
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Enhancement of the Electric Field and Diminishment of the Group Velocity of Light in Dielectric Multilayer Systems: A General Description
摘要： We present analytical formulae for light propagation through a multilayer of dielectric media as a function of the “total charge” and the “accumulated charge” that we propose by the transfer-matrix method. We redefine the concept of the total charge introduced by Liu et al. [J. Phys. Condens. Matter. 29, 455303 (2017)] and newly define the accumulated charge to determine the magnitude of electric field inside the multilayers analytically. In addition, we derive an analytical expression for the group velocity of light in each layer. The purpose of this work is to predict which kind of sequence would provide the strongest amplification of the electric field inside the multilayer as well as to find the sequence that gives the lowest group velocity. We find that the symmetric alternating sequence gives the best amplification of the electric field and the lowest mean group velocity compared with the other sequences.
关键词： dielectric multilayer systems,group velocity,transfer-matrix method,electric field enhancement
更新于2025-09-09 09:28:46
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[IEEE 2018 Photonics North (PN) - Montreal, QC, Canada (2018.6.5-2018.6.7)] 2018 Photonics North (PN) - Double Hot-Spot Dual-Polarization Chand-Bali Nanoantenna for NIR Detection Applications
摘要： In this work, we introduce a novel design of a gold nanoantenna array. The nanoantenna consists of two elliptical patches. A vertical oval coincides with the minor axis of the horizontal oval. An elliptical aperture etched out from the horizontal one resulting in our Chand-Bali shaped nanoantenna. The geometrical dimensions are properly selected such that two symmetrical small gaps are created. The electric field intensity has a significant enhancement in these two gaps at the same resonance frequency within the near-infrared (NIR) regime for both orthogonal polarizations. The new design offers an improved performance for IR detection and harvesting applications.
关键词： energy harvesting,nanoantenna,NIR,dual polarization,electric field enhancement
更新于2025-09-04 15:30:14
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Size and shape effects on the field enhancement induced at a silver triangular tip
摘要： A computational study is conducted on the near field enhancement induced by localized surface plasmon resonance (LSPR) around a silver nanotape of various sizes and shapes. The results show the consistent dominance of the dipole field generated at the rectangular Ag nanotape surfaces of various lengths by a normal incident electromagnetic plane wave of polarization along the long edge. The dipole field is further shown to exhibit monotonous spectral redshifts and increased magnitudes with increased length (?) of the rectangular nanotape. In contrary, the spectral peak and the field magnitude do not show the simple consistent variations with varied apex angle (θ) of the triangular nanotape. The calculated result for the triangular tape does exhibit the largely concentrated near field magnitude at the tip. It is found that a remarkable enhancement factor of 107 is attained at θ = 45° and ? = 50 nm.
关键词： field enhancement,silver triangular tip,localized surface plasmon resonance,computational study
更新于2025-09-04 15:30:14
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Theoretical study on surface plasmon properties of gold nanostars
摘要： With the rapid development of nanotechnology, the surface plasmon properties of metal nanostructures have become the focus of research. In this paper, a multi-tip gold nanostars (GNSs) structure is designed theoretically, and its surface plasmon properties are simulated by using the finite element method (FEM), which is practical and versatile. Compared with the traditional spherical and triangular plate particles, the results show that the tip structure of the GNSs has a stronger hot spots effect, resulting in greater local field enhancement properties. The relationship between the structure parameters of GNSs and their resonance peaks was also studied. The results indicate that the resonance peaks of GNSs depend strongly on the size, spacing between two GNSs, quantity and refractive index of the GNSs.
关键词： surface plasmon,finite element method,resonance peaks,gold nanostars,local field enhancement
更新于2025-09-04 15:30:14