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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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A Compact Impedance Model of Plasmonic Nanoshell for Metamaterial Applications
摘要： Recent research in plasmonics demonstrated merging different materials and shapes to form complex geometries with improved optical response. One of the most extensively used nanostructure is the coated nanosphere (nanoshell), which finds its application in diverse fields of medical, science and engineering. In this paper, we propose a compact impedance model of metallic core nanoshell. The model is based on time-varying approach by solving full dipole equation for the metallic core and impedance of the dielectric shell is derived using near-field components of the dipole field. The expressions for the absorption and scattering cross-sectional areas, and their behavior with change in the dielectric function are derived for the first time for nanoshell using voltages, currents and circuit elements, with their equivalence compared with exact solution. Additionally, the effects of changes in nanoshell parameters (dielectric constants, thickness of shell layer and radii of core) on the resonance frequency predicted by the proposed impedance model are analyzed. The simplified impedance model is based on parallel resonance circuit and contributes to the better understanding the behavior of nanoshell and facilitate cost-effectiveness solution for the next generation nanoshell based metamaterials.
关键词： nanophotonics,coated sphere,impedance model,metamaterial,plasmonics,Nanoshell,nanocircuit,dipole
更新于2025-09-11 14:15:04
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A theory of waveguide design for plasmonic nanolasers
摘要： We propose a theory for the waveguide design and analysis for plasmonic nanolasers by reformulating the fundamental waveguide requirements. This theory does not rely on further optimizing previously used structures, but examines each possible design without prejudice. Our exploration of one-dimensional (i.e., layered) plasmonic nanowaveguide geometries and the subsequent extension to 2D structures not only provides a deep understanding of the characteristics of currently used designs, but also leads to superior structures with the potential to address long-standing challenges in plasmonic nanolasers. In addition, we discover analogies between the reformulated fundamental requirements for the waveguide for nanolasers and nanoscale four-wave mixing (FWM) devices. Therefore, after a slight modification, our theory can also be applied to the waveguide design for plasmonic FWM devices.
关键词： four-wave mixing,waveguide design,nanophotonics,plasmonic nanolasers
更新于2025-09-11 14:15:04
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A rotary plasmonic nanoclock
摘要： One of the fundamental challenges in nanophotonics is to gain full control over nanoscale optical elements. The precise spatiotemporal arrangement determines their interactions and collective behavior. To this end, DNA nanotechnology is employed as an unprecedented tool to create nanophotonic devices with excellent spatial addressability and temporal programmability. However, most of the current DNA-assembled nanophotonic devices can only reconfigure among random or very few defined states. Here, we demonstrate a DNA-assembled rotary plasmonic nanoclock. In this system, a rotor gold nanorod can carry out directional and reversible 360° rotation with respect to a stator gold nanorod, transitioning among 16 well-defined configurations powered by DNA fuels. The full-turn rotation process is monitored by optical spectroscopy in real time. We further demonstrate autonomous rotation of the plasmonic nanoclock powered by DNAzyme-RNA interactions. Such assembly approaches pave a viable route towards advanced nanophotonic systems entirely from the bottom-up.
关键词： DNA nanotechnology,nanophotonics,DNAzyme-RNA interactions,plasmonic nanoclock,gold nanorod
更新于2025-09-11 14:15:04
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Deep UV plasmonic enhancement of single protein autofluorescence in zero-mode waveguides
摘要： Single molecule detection provides detailed information about molecular structures and functions, but it generally requires the presence of a fluorescent marker which can interfere with the activity of the target molecule or complicate the sample production. Detecting a single protein with its natural UV autofluorescence is an attractive approach to avoid all the issues related to fluorescence labelling. However, the UV autofluorescence signal from a single protein is generally extremely weak. Here, we use aluminum plasmonics to enhance the tryptophan autofluorescence emission of single proteins in the UV range. Zero-mode waveguides nanoapertures enable observing the UV fluorescence of single label-free β-galactosidase proteins with increased brightness, microsecond transit times and operation at micromolar concentrations. We demonstrate quantitative measurements of the local concentration, diffusion coefficient and hydrodynamic radius of the label-free protein over a broad range of zero-mode waveguide diameters. While the plasmonic fluorescence enhancement has generated a tremendous interest in the visible and near-infrared parts of the spectrum, this work pushes further the limits of plasmonic-enhanced single molecule detection into the UV range and constitutes a major step forward in our ability to interrogate single proteins in their native state at physiological concentrations.
关键词： plasmonics,ultraviolet UV,single molecule fluorescence,nanophotonics,zero-mode waveguide,tryptophan autofluorescence
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Dispersion Engineered Metasurfaces for Broadband Achromatic Optics
摘要： Chromatic aberrations in lenses are challenging to correct over large bandwidth. We show that dispersion-tailored and polarization-insensitive metasurfaces comprising counterintuitive anisotropic nanofins can correct the chromatic aberrations from simple singlet lenses to sophisticated microscope objectives with unprecedented compactness.
关键词： Nanophotonics,Dispersion engineering,Metasurfaces
更新于2025-09-11 14:15:04
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Tunable Quantum Beat of Single Photons Enabled by Nonlinear Nanophotonics
摘要： We demonstrate the tunable quantum beat of single photons through the co-development of core nonlinear nanophotonic technologies for frequency-domain manipulation of quantum states in a common physical platform. Spontaneous four-wave mixing in a nonlinear resonator is used to produce nondegenerate, quantum-correlated photon pairs. One photon from each pair is then frequency shifted, without degradation of photon statistics, using four-wave-mixing Bragg scattering in a second nonlinear resonator. Fine tuning of the applied frequency shift enables tunable quantum interference of the two photons as they are impinged on a beam splitter, with an oscillating signature that depends on their frequency difference. Our work showcases the potential of nonlinear nanophotonic devices as a valuable resource for photonic quantum-information science.
关键词： four-wave-mixing Bragg scattering,nonlinear nanophotonics,frequency-domain manipulation,quantum interference,quantum states,quantum beat,single photons,photonic quantum-information science,quantum-correlated photon pairs,spontaneous four-wave mixing
更新于2025-09-11 14:15:04
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Bioinspired Toolkit Based on Intermolecular Encoder toward Evolutionary 4D Chiral Plasmonic Materials
摘要： Over the last two decades, nanophotonics, including plasmonics and metamaterials, have promised compelling opportunities for exotic control over light?matter interactions. The strong chiral light?matter interaction is a representative example. Three-dimensional (3D) chirality has existed naturally only in organic molecules and bio-organisms, but a negligible chiroptic effect was attained with these naturally occurring materials because of their small absorption cross sections. However, inspired by biological chirality, nanophotonic chiral materials have greatly expanded the design space of accessible chiroptic effects (e.g., pushing the chiral light?matter interaction to an exceptional regime, such as a broad-band circular polarizer, negative refractive index, and sensitive chiral sensing). Nevertheless, it is still a challenge to achieve precisely defined and dynamically reconfigurable chiral morphologies that further increase the chiroptic effect.
关键词： plasmonics,metamaterials,chiroptic effects,nanophotonics,chiral light?matter interaction,3D chirality
更新于2025-09-11 14:15:04
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Tuning Spontaneous Emission through Waveguide Cavity Effects in Semiconductor Nanowires
摘要： The ability to tailor waveguide cavities and couple them with quantum emitters has developed a realm of nano-photonics encompassing, for example, highly efficient single photon generation or the control of giant photon nonlinearities. Opening new grounds by pushing the interaction of the waveguide cavity and integrated emitters further into the deep subwavelength regime, however, has been complicated by nonradiative losses due to the increasing importance of surface defects when decreasing cavity dimensions. Here, we show efficient suppression of nonradiative recombination for thin waveguide cavities using core?shell semiconductor nanowires. We experimentally reveal the advantages of such nanowires, which host mobile emitters, that is, free excitons, in a one-dimensional (1D) waveguide, highlighting the resulting potential for tunable, active, nanophotonic devices. In our experiment, controlling the nanowire waveguide diameter tunes the luminescence lifetime of excitons in the nanowires across 2 orders of magnitude up to 80 ns. At the smallest wire diameters, we show that this luminescence lifetime can be manipulated by engineering the dielectric environment of the nanowires. Exploiting this unique handle on the spontaneous emission of mobile emitters, we demonstrate an all-dielectric spatial control of the mobile emitters along the axis of the 1D nanowire waveguide.
关键词： Semiconductor nanowire,free excitons,photonic waveguide cavity,subwavelength nanophotonics,luminescence lifetime,tunable spontaneous emission
更新于2025-09-11 14:15:04