scholarly journals Active Switching of Toroidal Resonances by Using a Dirac Semimetal for Terahertz Communication

2020 ◽  
Vol 8 ◽  
Author(s):  
Yuanbao Sun ◽  
Denggao Liao ◽  
Jinjin Xu ◽  
Yiping Wu ◽  
Lin Chen
Keyword(s):  
Fermi Level ◽  
Switching Effect ◽  
Hybrid Mode ◽  
Plasmonic Mode ◽  
Toroidal Mode ◽  
Dual Channel ◽  
Dirac Semimetal ◽  
Dipole Resonance ◽  
Terahertz Communication ◽  
Potential Applications

The dynamical switching of a toroidal dipole resonance channel is demonstrated by tuning the Fermi level of a Dirac semimetal film sandwiched between the back substrates. As the Fermi level is increased from 30 to 150 meV, the resonance frequency is switched from 0.283 to 0.201 THz because of the transition from toroidal mode to hybrid mode. The hybrid mode is formed by the interaction between the toroidal mode and the plasmonic mode (induced by a Dirac semimetal film with metallic properties). The influence of the sandwiched dielectric layer (between the toroidal metasurface pattern and the Dirac semimetal film) on the switching effect was also investigated. This active dual-channel terahertz switching may have potential applications in advanced terahertz communication.

Integration of Lenticular Displays with Image Switching and Infrared Watermark

2015 ◽  
Vol 764-765 ◽  
pp. 1260-1264
Author(s):  
Yen I Liao ◽  
Hsi Chun Wang
Keyword(s):  
Carbon Material ◽  
Value Added ◽  
Infrared Detection ◽  
Infrared Light ◽  
Switching Effect ◽  
Digital Halftoning ◽  
Brand Protection ◽  
Potential Applications ◽  
Lenticular Lens ◽  
Lens Image

The objective of this paper is to integrate lenticular lens with switching images and embedding the infrared watermark to provide value-added and anti-counterfeiting features. Digital halftoning technique has been used to compose animated graphics and the infrared watermark. The infrared watermark consists of halftone dots in cyan, magenta, yellow, and black inks. The carbon material in black ink absorbs the infrared light and the watermark could be displayed under infrared detection. By using the lenticular lens, image-switching effect can be observed from different viewing angles. The results show that it is successful to implement a lenticular display with both image-switching feature and hidden watermark which can be decoded under infrared detection. The proposed method has many potential applications to anti-counterfeiting and brand protection.

scholarly journals Small-Angle Ultra-Narrowband Tunable Mid-Infrared Absorber Composing from Graphene and Dielectric Metamaterials

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 825
Author(s):  
Yan-Lin Liao ◽  
Huilin Wang ◽  
Yan Zhao ◽  
Xiang Chen ◽  
Jing Wu ◽  
...  
Keyword(s):  
Fermi Level ◽  
Small Angle ◽  
Resonance Absorption ◽  
Thermal Source ◽  
Mid Infrared ◽  
One Dimensional ◽  
Fabry Perot ◽  
Potential Applications ◽  
The One ◽  
Resonance Cavity

We report a small-angle ultra-narrowband mid-infrared tunable absorber that uses graphene and dielectric metamaterials. The absorption bandwidth of the absorber at the graphene Fermi level of 0.2 eV is 0.055 nm, and the absorption peaks can be tuned from 5.14803 to 5.1411 μm by changing the graphene Fermi level. Furthermore, the resonance absorption only occurs in the angle range of several degrees. The simulation field distributions show the magnetic resonance and Fabry–Pérot resonance at the resonance absorption peak. The one-dimensional photonic crystals (1DPCs) in this absorber act as a Bragg mirror to efficiently reflect the incidence light. The simulation results also show that the bandwidth can be further narrowed by increasing the resonance cavity length. As a tunable mid-infrared thermal source, this absorber can possess both high temporal coherence and near-collimated angle characteristics, thus providing it with potential applications.

scholarly journals Design of Metasurface with Nanoslits on Elliptical Curves for Generation of Dual-Channel Vector Beams

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3024
Author(s):  
Xiaorong Ren ◽  
Manna Gu ◽  
Xiangyu Zeng ◽  
Rui Sun ◽  
Yuqin Zhang ◽  
...  
Keyword(s):  
Focal Point ◽  
Polarized Light ◽  
Spin Component ◽  
Destructive Interference ◽  
Constructive Interference ◽  
Dual Channel ◽  
Vector Beams ◽  
Linearly Polarized ◽  
Potential Applications ◽  
Difference Time

The manipulations of nanoscale multi-channel vector beams (VBs) by metasurfaces hold potential applications in various important fields. In this paper, the metasurface with two sets of nanoslits arranged on elliptic curves was proposed to generate the dual-channel focused vector beams (FVBs). Each set of nanoslits was composed of the in-phase and the out-of-phase groups of nanoslits to introduce the constructive interference and destructive interference of the output light field of the nanoslits, focusing the converted spin component and eliminating the incident spin component at the focal point. The two sets of nanoslits for the channels at the two focal points were interleaved on the same ellipses, and by setting their parameters independently, the FVBs in the two channels are generated under illumination of linearly polarized light, while their orders and polarization states of FVBs were controlled independently. The generation of the FVBs with the designed metasurfaces was demonstrated by the finite-difference time domain (FDTD) simulations and by the experimental verifications. The work in this paper is of great significance for the generation of miniaturized multi-channel VBs and for broadening the applications of metasurfaces.

scholarly journals Dual Toroidal Dipole Resonance Metamaterials under a Terahertz Domain

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2036 ◽  
Author(s):  
Shuang Wang ◽  
Song Wang ◽  
Quan Li ◽  
Xiaoli Zhao ◽  
Jianyu Zhu
Keyword(s):  
High Frequency ◽  
Coupling Effect ◽  
Energy Levels ◽  
Low Frequency ◽  
Ring Resonators ◽  
Multipole Interaction ◽  
Practical Applications ◽  
Dipole Resonance ◽  
Potential Applications ◽  
Quality Factor Q

We proposed and fabricated a flexible, planar, U-shape-modified structure metamaterial (MM) that was composed of two metallic pattern layers separated by a polyimide layer, where each metallic pattern layer consists of two U-shaped split ring resonators (USRRs). The coupling effect between the two USRRs in the same metallic layer was vital to the formation of dual toroidal dipole (TD) resonances. The measured and simulated results showed that both low quality factor (Q) (~1.82) and high Q (~10.31) TD resonances were acquired synchronously at two different frequencies in the MMs by adjusting the distance between the two coplanar USRRs. With the interaction of the USRRs, the energy levels of the USRRs were split into inductance-capacitance (LC)-induced TD resonance at low frequency and dipole-induced TD resonance at high frequency. Thus, the electric multipole interaction played an important role in determining the energy level of the TD resonance. The better strength of the high frequency TD resonance can be confined to an electromagnetic field inside a smaller circular region, and thus, a higher Q was obtained. In order to investigate the TD mechanism more in depth, the power of the electric dipole, magnetic dipole, electric circular dipole, and TD were quantitatively calculated. Dual TD MMs on a freestanding substrate will have potential applications in functional terahertz devices for practical applications.

scholarly journals Prediction of crossing nodal-lines and large intrinsic spin Hall conductivity in topological Dirac semimetal Ta3As family

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wenjie Hou ◽  
Jian Liu ◽  
Xi Zuo ◽  
Jian Xu ◽  
Xueying Zhang ◽  
...  
Keyword(s):  
Fermi Level ◽  
Hall Conductivity ◽  
Spin Orbit Coupling ◽  
First Principles Calculations ◽  
Practical Applications ◽  
Nodal Lines ◽  
Dirac Semimetal ◽  
Topological Semimetals ◽  
The Ideal ◽  
Spin Hall Conductivity

AbstractTopological insulators (TIs) are considered as ideal platforms for generating large spin Hall conductivity (SHC), however, the bulk carrier problem, which is unavoidable in TIs, hinders their practical applications. Recently, topological semimetals (TSMs) have been proposed to achieve large SHC to replace TIs. However, the ideal TSM candidates with large SHC are still lacking. In terms of first-principles calculations, we predict that Ta3As family compounds exhibit complex crossing nodal-lines (CNL) properties in absence of the spin-orbit coupling (SOC). However, they transfer to Dirac TSMs under the influence of strong SOC, and present large SHC around Fermi level in particular. Remarkably, the SHC value of Ta3Y (Y = As, Sb, Bi) is around 1500–1700 $$(\hbar /e)({\mathrm{{\Omega}}} \cdot {\mathrm{cm}})^{ - 1}$$ ( ħ / e ) ( Ω ⋅ cm ) − 1 , which is comparable to noble metal Pt and much larger than TIs, Weyl TSMs, and 4d/5d transition metals. Our work not only suggests a kind of TSM family with interesting Dirac CNL around Fermi level, but also paves the way for searching large intrinsic SHC materials in complex CNL TSM systems.

scholarly journals Transmission type Dual-frequency Vortex Beams Generator for Multiple OAM Modes

2021 ◽  
Author(s):  
L. Zhang ◽  
J. Li
Keyword(s):  
Angular Momentum ◽  
Communication System ◽  
System Capacity ◽  
Vortex Beam ◽  
Dual Frequency ◽  
Convolution Operation ◽  
Terahertz Communication ◽  
Potential Applications ◽  
Vortex Beams ◽  
Topological Charges

Abstract We design a transmission-type metasurface to generate terahertz dual-frequency orbital angular momentum (OAM) vortex beams with different topological charges (l = 1, l = 2) at frequency of 0.81THz and 1.63THz. By adding a deflection factor, the proposed metasurface produces a OAM vortex beam with a preset tilted direction at two frequencies. By utilizing a complex convolution operation, we can achieve two symmetric tilted beams with different topological charges (l = 1, l=-1) at two frequencies on the same metasurface. These OAM vortex beams can effectively improve communication system capacity, and have potential applications in terahertz communication.

STRUCTURAL AND ELECTRONIC PROPERTIES OF Pd AND Au MONOLAYERS ADSORBED ON MoS2: A COMPARATIVE STUDY FROM DFT CALCULATIONS

2018 ◽  
Vol 25 (06) ◽  
pp. 1850117
Author(s):  
PING WU ◽  
NAIQIANG YIN ◽  
WENJING CHENG ◽  
PENG LI
Keyword(s):  
Fermi Level ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Electrode Materials ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Potential Applications ◽  
Work Functions

The morphology, stability and electronic properties of Pd and Au monolayers supported by MoS2 substrate have been investigated by using the first principles calculations based on periodic density functional theory (DFT). The results demonstrated that the most stable site is top of Mo top of S ([Formula: see text]) for the adsorption of Pd and Au monolayers on MoS2. We found that Pd/MoS2 with lower adsorption energy of [Formula: see text]0.54[Formula: see text]eV is energetically more stable than Au/MoS2. Due to the emergence of impurities state in the bandgap of MoS2, Pd/MoS2 and Au/MoS2 display metallic character upon coating of metal monolayers. We demonstrated that the Pd monolayer strongly hybrids with underlying Mo and S around the Fermi level, which is achieved by the intermediate Pd–S–Mo hybridized chains. On the contrary, intensity of impurities states around the fermi level is much weaker for Au/MoS2, which can be explained by weak hybridizations between sp state of Au and 4[Formula: see text] state of nearest neighboring Mo. The calculated results demonstrated that work functions are markedly modulated to 4.99 and 6.23[Formula: see text]eV after coating of Pd and Au monolayer, respectively, which can be qualitatively explained by the fact that Pd (as accepter) received charge from the MoS2 host, while Au donated charge to the host. These findings promise potential applications in the fields of nanoelectronics in future, such as it's helpful to choose suitable electrode materials for MoS2-based nanodevices.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

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