- 标题
- 摘要
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- 实验方案
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Graphene-Based Biosensors for Detection of Composite Vibrational Fingerprints in the Mid-Infrared Region
摘要： In this study, a label-free multi-resonant graphene-based biosensor with periodic graphene nanoribbons is proposed for detection of composite vibrational ?ngerprints in the mid-infrared range. The multiple vibrational signals of biomolecules are simultaneously enhanced and detected by di?erent resonances in the transmission spectrum. Each of the transmission dips can be independently tuned by altering the gating voltage applied on the corresponding graphene nanoribbon. Geometric parameters are investigated and optimized to obtain excellent sensing performance. Limit of detection is also evaluated in an approximation way. Besides, the biosensor can operate in a wide range of incident angles. Electric ?eld intensity distributions are depicted to reveal the physical insight. Moreover, another biosensor based on periodic graphene nanodisks is further proposed, whose performance is insensitive to the polarization of incidence. Our research may have a potential for designing graphene-based biosensor used in many promising bioanalytical and pharmaceutical applications.
关键词： nanophotonics,label-free biosensors,surface plasmons,graphene,metasurface
更新于2025-09-11 14:15:04
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Exciting Pseudospin-Dependent Edge States in Plasmonic Metasurfaces
摘要： We study a plasmonic metasurface that supports pseudospin dependent edge states confined at a subwavelength scale, considering full electrodynamic interactions including retardation and radiative effects. The spatial symmetry of the lattice of plasmonic nanoparticles gives rise to edge states with properties reminiscent of the quantum spin Hall effect in topological insulators. However, unlike the spin-momentum locking characteristic of topological insulators, these modes are not purely unidirectional and their propagation properties can be understood by analysing the spin angular momentum of the electromagnetic field, which is inhomogenous in the plane of the lattice. The local sign of the spin angular momentum determines the propagation direction of the mode under a near-field excitation source. We also study the optical response under far-field excitation and discuss in detail the effects of radiation and retardation.
关键词： nanophotonics,nanoparticle array,topological photonics,plasmonics,pseudospin,metasurface
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - A Dual-Steerable-Beam Multi-Slot Coupled Metasurface Antenna
摘要： This manuscript proposes a dual-steerable-beam multi-slot coupled metasurface antenna for a potential candidate of the indoor base station application. It consists of 7×10 metasurface cells coupled by 4 unequal-spacing slots with a two-port microstrip feeding line. The steerable beams are readily obtained by applying some phase differences between adjacent coupling slots. As a result, the operating band of the proposed antenna ranges from 5.15 GHz to 5.35 GHz for applications of LTE-U band in China. The 10-dB beamwidth of the two beams is around 120° in YOZ plane and the cross level at the junction of the two beams is around -10 dB. Compared with conventional multi-beam antenna arrays, the proposed antenna implements two steerable beams without complex beam-forming network or phase shifters, which can be easily extended to multi-beam indoor base station array design.
关键词： indoor base station application,LTE-U band,metasurface antenna,dual-steerable-beam
更新于2025-09-11 14:15:04
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Dual-band asymmetric optical transmission of both linearly and circularly polarized waves using bilayer coupled complementary chiral metasurface
摘要： It is highly desirable to develop asymmetric transmission (AT) devices for both linearly and circularly polarized light. However, currently existing metamaterial-based AT devices require multi-step micro-nano fabrication processes and usually realize AT responses only for linearly or circularly polarized waves, not simultaneously for both. We here propose a dual-band AT device for both linearly and circularly polarized waves in the near-infrared region by using a bilayer coupled complementary chiral metasurface, which includes a half-gammadion-shape gold (Au) structural layer and its Babinet’s complimentary copy. Unlike other multilayer AT devices working at optical frequencies, it takes less micro-nano fabrication steps. Besides, with the help of chirality and the inherent near-?eld coupling e?ect between the two complementary Au layers, the maximal AT parameters for linearly and circularly polarized waves can reach up to 0.45 and 0.56, respectively. The underlying mechanisms of dual-band AT responses are also investigated in depth from the perspectives of chirality and coupling e?ect. Our work o?ers a new and simple approach to high-performance AT devices, helps to better understand near-?led coupling e?ect in coupled complementary metasurfaces, and also expands their application ?elds.
关键词： chiral metasurface,asymmetric transmission,polarization conversion,coupling effect,near-infrared
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) - Dallas, TX, USA (2019.8.4-2019.8.7)] 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) - Logic Obfuscation using Metasurface Holography
摘要： Over the years, system design companies have developed sophisticated and accurate Reverse Engineering (RE) tools to debug the functionality of their own designs, ensure the legitimacy of their Intellectual Properties (IPs), and to some extent- gather information on their competitors. Technologies such as optical imaging, Scanning Electron Microscopy (SEM), Tunneling Electron Microscopy (TEM), X-ray Tomography, etc. have made it possible to acquire images of individual layers of a delayered Integrated Circuit (IC) with super?ne resolution. State-of-the-art tools such as ICWorks from Chipworks can perform automatic extraction of netlists from images of each layer. An adversary can unlock valuable IPs through such attacks and pirate the design or sell the cloned IP to other competitors for unjust motives. Logic and interconnect obfuscation have been proposed to make the RE effort behind such approaches prohibitively high for the adversaries. Several solutions have been proven to be vulnerable to Satis?ability (SAT) based attacks where an adversary can deobfuscate the circuit reasonably quickly. In this paper, we have presented a novel obfuscation technique based on the concepts of cloaked nets and fake holographic gates using metasurface holography. The proposed approach can address optical and X-ray imaging based RE.
关键词： IC Camou?aging,Metasurface Holography,Cloaked Nets,Reverse Engineering,Fake Gates
更新于2025-09-11 14:15:04
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Electrotunable Nanoplasmonics for Amplified Surface Enhanced Raman Spectroscopy
摘要： Tuning the properties of optical metamaterials in real time is one of the grand challenges of photonics. Being able to do so will enable a class of adaptive photonic materials for use in applications such as surface enhanced Raman spectroscopy and reflectors/absorbers. One strategy to achieving this goal is based on the electrovariable self-assembly and disassembly of two-dimensional nanoparticle arrays at a metal liquid interface. As expected, the structure results in plasmonic coupling between NPs in the array but perhaps as importantly between the array and the metal surface. In such a system the density of the nanoparticle array can be controlled by the variation of electrode potential. Due to the additive effect, we show that less than 1 V variation of electrode potential can give rise to a dramatic simultaneous change in optical reflectivity from ~93 % to ~1 % and the amplification of the SERS signal by up to 5 orders of magnitude. The process allows for reversible tunability. These concepts are demonstrated in this manuscript, using a platform based on the voltage-controlled assembly of 40 nm Au-nanoparticle arrays at a TiN/Ag electrode in contact with an aqueous electrolyte. We show that all the physics underpinning the behaviour of this platform works precisely as suggested by the proposed theory, setting the electrochemical nanoplasmonics as a promising direction in photonics research.
关键词： plasmonics,surface enhanced Raman spectroscopy,electrotunable,nanoparticles,metasurface,self-assembly
更新于2025-09-11 14:15:04
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Handbook of Graphene || Graphene Plasmonic: Switching Applications
摘要： This chapter focuses on the graphene plasmonic-based optical switching devices operating in the infrared to terahertz spectrum. Graphene plasmonic due to high strong light–matter interaction and nanoscale size has received significant attention in recent years, as they have found an important role in many areas of optical science and engineering by offering schemes to control electromagnetic fields. Another area of science that has been under the spotlight for the last few years relates to graphene plasmonic metasurface, which is formed of graphene layer packed into a structure. This material exhibits exceptional electronic and optical properties, intriguing many research groups across the world including us. However, our interest is specifically in studying the interaction between electromagnetic waves with surface modes of graphene in multilayer configuration (such as Otto configuration) and switching applications that might follow. In this chapter, relying on theoretical models and numerical simulations, we show that by designing and manipulating optical and electrical properties of graphene such as chemical potential, temperature, scattering rate, as well as incident beam characteristics such as beam width, one can have the structures based on graphene as a good platform for not only infrared optical switching devices but also terahertz switching devices.
关键词： Otto configuration,Graphene plasmonic,graphene conductivity,optical switches,terahertz,metasurface
更新于2025-09-11 14:15:04
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Continuously Tunable Acoustic Metasurface for Transmitted Wavefront Modulation
摘要： Previously reported acoustic metasurfaces consisting of fixed channels are untunable to meet broadband requirements and alterable functionalities. To overcome this limitation, we propose a screw-and-nut mechanism of tunability and design a type of continuously tunable acoustic metasurface with unit components of helical cylinders which are screwed into a plate. The spiral channel length can be tuned continuously by the screwed depth, and thus a metasurface with a continuously tunable acoustic phase of independent pixels is attained. Different distributions of the unit components can form an arbitrary metasurface profile. We also develop an approximate equivalent medium model to predict the tunability of the unit component. As an example, we present the design details of a circular tunable metasurface for three-dimensional (3D) adjustable broadband acoustic focusing of different airborne sound sources in a wide frequency range. A sample of the metasurface is manufactured by polylactic acid plastic with 3D-printed helical cylinders. Experiments of the adjustable acoustic focusing are performed to validate the equivalent medium model and the finite element simulation. It is shown that the results of the equivalent medium model, the finite element simulation, and the experiments are in good agreement.
关键词： 3D printing,acoustic metasurface,acoustic focusing,broadband,tunable
更新于2025-09-11 14:15:04
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Dynamic metasurface based cavity structures for enhanced absorption and phase modulation
摘要： Metasurface based optical cavity structures consist of a metallic metasurface realized on top of a dielectric slab backed with a metal plane. Such structures have been employed in the design of optical devices such as flat lenses, wave plates and holograms at frequencies from microwave to mid-infrared. Recently, such structures with dynamically reconfigurable optical characteristics have been explored for electrically tunable optical absorption and reflection phase modulation. To date, absorption modulation and phase modulation have been realized with large insertion loss. In this work, we employ an analytical approach based on transmission line theory where the metasurface is represented by a surface admittance. We extend the above approach for the design and analysis of under and over coupled resonance regimes in metasurface cavity structure. This enables a mutual design of cavity thickness and individual metasurface for large amplitude or phase modulation. A dynamic metasurface based optical cavity is experimentally demonstrated at THz frequencies where the dynamic metasurface consists of metallic resonators embedded with thin film vanadium dioxide patches. By driving insulator to metal transition in vanadium dioxide, the THz optical response of the metasurface based cavity structure is modulated. The fabricated device exhibits perfect absorption modulation and reflection phase modulation up to 180°. The reported results demonstrate the potential of such structures for realizing novel devices such as tunable holograms, high-efficiency modulators and frequency tunable filters at THz. The analytical approach presented here can be applied for analysis and design of metasurface cavity structures based on other material systems at frequencies ranging from THz to mid-infrared.
关键词： Terahertz,Phase modulator,Dynamic metasurface,Perfect absorption modulator,Metasurface optical cavity
更新于2025-09-10 09:29:36
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Enhancing the Number of Modes in Metasurfaced Reverberation Chambers for Field Uniformity Improvement
摘要： The use of metasurfaces to increase the number of modes, lower the operating frequency, and improve the field uniformity in reverberation chambers (RCs) is investigated in this paper. The method used to improve the field uniformity and decrease the resonance frequencies is based on increasing the number of modes by using the concept of subwavelength cavities. The resonance frequencies of a RC with metasurface wall are derived and expressed analytically in terms of macroscopic characteristics. Simulation of the reflection phase of the unit cell is then given as a guideline to choose the required microscopic parameters of the designed metasurface. The mode density in such subwavelength RCs is then obtained using a numerical eigenmode solver. Compared to traditional RCs, a much higher modal density is obtained at low frequencies. The standard deviation of the field uniformity in the test volume of the RC corresponding to different types of metasurface walls is finally compared. It is shown that by increasing the number of modes in the RC at the lower band, the operating frequency decreases and the field uniformity of the RC is improved.
关键词： modes,field uniformity,metasurface,reverberation chamber
更新于2025-09-10 09:29:36