共查询到20条相似文献,搜索用时 15 毫秒
1.
Plasmonics - We derive and present systematic relationships between the analytical formulas for calculation of the localized surface plasmon resonances (LSPR) of some plasmonic nanostructures which... 相似文献
2.
Plasmonics - We present a numerical study of the plasmonic properties of Au core-semishell. Symmetry breaking in semishell results in a dipole–quadrupole Fano resonance without the offset of... 相似文献
3.
Surface plasmon polaritons (SPPs) have appealing features such as tighter spatial confinement and higher local field intensity. Manipulation of surface plasmon polaritons on metal/dielectric interface is an important aspect in the achievement of integrated plasmonic circuit beyond the diffraction limit. Here, we introduce a design of pin cushion structure and a holographic groove pattern structure for tunable multi-port SPPs excitation and focusing. Free space light is coupled into SPPs through momentum matching conditions. Both nanostructures are capable of tunably controlling of SPPs depending on the incident polarizations, while the holographic method provides more flexibility of wavelength-dependent excitations. Furthermore, a quantitative method is applied to calculate the efficiencies of excitation for both nanostructures under different conditions, including radially polarized incident beams. These results can work as a guidance and be helpful to further choice of the suitable design strategies for variable plasmonic applications such as beam splitter, on-chip spectroscopy, and plasmonic detectors. 相似文献
4.
Linear clusters made by tightly connecting two or more metallic nanoparticles have new types of surface plasmon resonances as compared with isolated nanoparticles. These new resonances are sensitive to the size of the junction and to the number of interconnected particles and are described by eigenmodes of a boundary integral equation. This formulation allows effective separation of geometric and shape contribution from electric properties of the constituents. Results for particles covered by a thin shell are also provided highlighting ultrasensitive sensing applications. The present analysis sheds a new light on the interpretation of recent experiments. 相似文献
5.
We studied optical reflection properties of complex metal (Ag) surfaces with close-interspaced ultra-thin metal gratings.
Prominent reflection minima were observed corresponding to enhanced absorption of light. Our analysis convinced us that the
period-dependent mode is ascribed to Bloch-wave-like resonances of surface plasmon waves at the overall effective metal surfaces,
and the ridge-width-dependent mode to Fabry-Pérot-like resonances of localized surface plasmon waves in micro-/nanocavities
defined by regions of the grating ridges. The latter resonance mode is shown highly tunable with variation of the grating
ridge width. Such structures may be applied in spectrum resolvable photovoltaic devices, bio-sensing, and studying optical
properties of cavity-coupled molecules or functional nanomaterials. 相似文献
6.
The wavelength sensitivities of three kinds of nanostructures (nanoslits, nanoholes, and concentric circles) with various
aperture sizes were compared in water environment. These nanostructures were made on a 110-nm-thick gold film with a period
of 600 nm. Surface plasmon resonances in these nanostructures produce transmission dips near the phase-matching conditions
while peaks at longer wavelengths. The wavelength sensitivities measured at dips are close to theoretical predictions and
about 1.5 times larger than those measured at peaks. Such sensitivity difference is attributed to various surface plasmon
distributions, as illustrated by the finite-difference time-domain calculations. In addition, the sensitivity decreases with
the increase of aperture size. The nanoslit array and concentric circles have better sensitivities than the nanohole array
due to the no cut-off transmission. 相似文献
7.
Plasmonics - Graphene plasmonic resonances play a significant role for enhancing the photon absorption inside thin film solar devices. We investigate the field rising at the intersection of... 相似文献
8.
We suggest semi-analytical approach to study the optical properties of noble metal nanoparticles and their interaction to the perovskite material (methyl ammonia lead halide: CH 3NH 3PbI 3). Metal nanoparticles embedded in perovskite matrix exhibits broadband surface plasmon resonances, and the tunability of these plasmonic resonances is highly sensitive to particle size. The calculation of optical cross section have been done using Mie scattering theory which is applicable to arbitrary size and spherical-shape metal nanoparticles. We have taken five different radii ranging from 15 to 100 nm to understand the plasmonic resonances and its spectral width in the wavelength range 300 to 800 nm. Out of these noble metal nanoparticles, silver have highest scattering efficiency nearly of the order of 18 for the case of 15 nm radii at resonance wavelength 613 nm. Our finding reveals a new concept to understand the applications of plasmonic resonances in order to enhance the photon absorption inside the thin film of perovskite. 相似文献
9.
A metamaterial system composed of monolayer black phosphorus and Au triangle arrays is designed. Absorptivity, transmittivity, and reflectivity are investigated in mid-infrared regime. A low transmissivity and high absorptivity can be obtained via surface plasmon polaritons at the black phosphorus and Au triangle array interface. By changing the geometrical parameters, such as angle magnitude and slit width of Au triangle, we can modulate the transmissivity, reflectivity and absorptivity properties. Different from other previous work, it is found the zigzag direction has a better photoresponse than that armchair by changing the slit width. The electric field of the external radiation field is reflected at the Au triangle edges. Thus, electric field component perpendicular to the polarization direction generates, which can also lead to surface plasmon polaritons and is not researched in others’ work. With increase in the angle of Au triangle, transmittivity (or absorptivity) for armchair direction has a blue shift and for zigzag direction has a red shift. The transmittivity decrease ( or absorptivity increase ) for special wavelength caused by the surface plasmon polaritons may be applied to design filter devices. 相似文献
10.
We investigate theoretically the optical properties associated to plasmon resonances of metal nanowires with cross section
given by low-order Chebyshev nanoparticles (like rounded-tip nanostars or nanoflowers). The impact of the nanoflower shape
is analyzed for varying symmetry and deformation parameter through the spectral dependence of resonances and their corresponding
near field distributions. Large field intensity enhancements are obtained at the gaps between petals, apart from the tips
themselves, which make these nanostars/nanoflowers specially suitable to host molecules for surface-enhanced Raman scattering
sensing applications. 相似文献
11.
Plasmonics - Strongly coupled system is known to pose challenges, particularly those involving multitude of levels as in molecules. Surface plasmons offer intense and localized electromagnetic... 相似文献
12.
Plasmonics - We study the multipolar surface plasmon modes and its link to Fano resonances in bimetallic nanoparticles. General expressions for the multipolar surface plasmon frequencies and... 相似文献
13.
The optical properties of a compound structure with metallic nanoparticle and nanohole arrays are numerically investigated by the means of finite-difference time domain method. We report on the observation of multi-valleys in the reflection spectra due to the excitation of surface plasmon (SP) resonant modes of the compound structure. Simulation results show that multiple SP resonances consist of surface plasmon polaritons on the gold film, localized surface plasmons on the nanoparticles, and coupling mode between them. These findings are important for applications utilizing multiple surface plasmon resonances. 相似文献
14.
The effects of highly anisotropic dielectric on surface plasmon polaritons (SPPs) are investigated in several three-layer plasmonic nanostructures. Dispersion relations of SPPs in anisotropic-dielectric-metal (ADM), dielectric-anisotropic-metal (DAM), and metal-anisotropic-metal (MAM) structures are analytically derived. The numerical results in the visible indicate that, in ADM, the propagation length of a conductor-gap-dielectric mode is changed from 5.9 to 91 μm and its cutoff thickness from 83 to 7 nm with varying the optical axis, while in DAM, the influences of anisotropic dielectric are reversed on propagation length and cutoff thickness. In MAM, by tuning the optical axis, the light confinement of symmetry SPPs mode varies about 10 %. Further numerical calculations show that the above results induced by the anisotropy of dielectric can be extended to the telecommunication frequency. The improved mode properties may be used in plasmonic-based nanodevices and tunable single surface plasmon sources. 相似文献
15.
We have demonstrated experimentally a one-way magnetic surface plasmon (MSP) electromagnetic (EM) waveguide in the microwave range based on the magnetic photonic crystals (MPCs). The waveguide exhibits asymmetric transmission of EM waves in the frequency range near the MSP resonance for an MPC, such that a significant one-way propagation can be observed in the channel between the two MPC slabs, each in an external static magnetic field (ESMF) of opposite directions. The one-way waveguide is not only immune to interstitial metal defects but also robust against the disorder of rod position. Furthermore, its working frequency can be flexibly tuned by an ESMF, which makes it more favorable for the design of EM devices. The physics is related to the broken time-reversal symmetry of the MSP band states and the excitation of a giant circulation of the energy flow, similar to the case in the quantized Hall effect. 相似文献
16.
We report the synthesis and the characterization of core-shell Au@Ag nanorods through reduction by the wet chemical method. UV-visible absorption spectra of core-shell Au@Ag nanorods demonstrate the longitudinal mode of localized surface plasmon resonances (LSPRs) can be tailored from 724 to 786 nm by controlling the thickness of the silver shell, as is assessed by transmission electron microscope (TEM). Furthermore, the tunable and well-controlled LSPRs of core-shell Au@Ag nanorods are also investigated by numerical simulation using the finite difference time domain (FDTD) method, which strongly supports the experimental observations. The growth mechanism for core-shell Au@Ag nanorods is proposed, according to experimental observations and numerical calculations. 相似文献
17.
Surface plasmon resonances on bilayer aluminum nanowire gratings are studied in both theory and experiment. It is found that there are two kinds of surface plasmon on the bilayer metallic gating: longitudinal aluminum/dielectric/aluminum slit and lateral aluminum/dielectric interface waveguide mode. The surface plasmon waveguide mode resonance in the slits makes the grating act as a transverse magnetic (TM)-passing polarizer. With the lateral waveguide mode resonance, certain wavelengths of the incident TM light are translated to aluminum/air or aluminum/substrate waveguide light, and the grating acts as a color filter. With both resonances, the bilayer nanowire grating can be a compact-integrated polarizer and color filter. 相似文献
18.
I present a direct and intuitive eigenmode method that evaluates the near-field enhancement around the surface of metallic nanoparticles of arbitrary shape. The method is based on the boundary integral equation (BIE) in the electrostatic limit. Besides the nanoparticle polarizability and the far-field response, the near-field enhancement around nanoparticles can be also conveniently expressed as an eigenmode sum of resonant terms. Moreover, the spatial configuration of the near-field enhancement depends explicitly on the eigenfunctions of both the BIE integral operator and of its adjoint. It has also established a direct physical meaning of the two types of eigenfunctions. While it is well known that the eigenfunctions of the BIE operator are electric charge modes, it is less known and used that the eigenfunctions of the adjoint represent the electric potential generated by the charge modes. For the enhanced spectroscopies, the present method allows an easy identification of hot spots which are located in the regions with maximum charge densities and/or regions with fast variations of the electric potential generated by the charge modes on the surface. This study also clarifies the similarities and the differences between the far-field and the near-field behavior of plasmonic systems. Finally, the analysis of concrete examples like the nearly touching dimer, the prolate spheroid, and the nanorod illustrate some modalities to improve the near-field enhancement. 相似文献
19.
Tunable properties of localized surface plasmon resonances (LSPR) of gold-dielectric multilayered nanoshells are studied by quasi-static theory and plasmon hybridization theory. Multilayered nanoshells with the gold core and nanoshell separated by a spacer layer exhibit strong coupling between the core and nanoshell plasmon resonance modes. It is found that the absorption spectra characteristics of LSPR are sensitive to multiple parameters including the surrounding medium refractive index, the dielectric constant of spacer layer, the radius of inner core gold sphere, outer shell layer thickness, and their coupling strength. The results show that LSPR is mainly influenced by the ratio of spacer layer dielectric constant ε 2 to surrounding medium dielectric constant ε 4. Absorption spectrum of \(\left |\omega _{-}^{+}\right \rangle \) mode is red-shifted with increasing core radius when ε 2 > ε 4. It is surprising to find that LSPR is blue-shifted with increasing core radius when ε 2 < ε 4, and no shift when ε 2 = ε 4. These interesting contrary shifts of \(\left |\omega _{-}^{+}\right \rangle \) mode with different ratios ε 2/ ε 4 are well analysed with plasmon hybridization theory and the distributions of induced charges interaction between the inner core and outer shell. In addition, for the sake of clarity, the distributions of electric filed intensity at their plasmon resonance wavelengths are also calculated. This work may provide an alternative approach to analyse property of the core-shell nanoshell particles based on plasmon hybridization theory and the induced charge interaction. 相似文献
20.
Surface plasmon resonance imaging and surface plasmon induced fluorescent are sensitive tools for surface analysis. However, existing instruments in this area have provided limited capability for concurrent detection, and may be large and expensive. We demonstrate a highly cost-effective system capable of concurrent surface plasmon resonance microscopy (SPRM) and surface plasmon resonance-enhanced fluorescence (SPRF) imaging, allowing for simultaneous monitoring of reflectivity and fluorescence from discrete spatial regions. The instrument allows for high performance imaging and quantitative measurements with surface plasmon resonance, and surface plasmon induced fluorescence, with inexpensive off-the-shelf components. 相似文献
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