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1.
The propagation of a surface plasmon polariton wave at the interface of a metal and an ambichiral nanostructured medium was theoretically investigated in the Kretschmann configuration using transfer matrix method. The dependence of optical absorption linear polarization on structural parameters was reported. The results were compared with those obtained from the interface of a metal and a chiral dielectric medium as a reference structure. We found that multiple plasmon modes are excited at the interface of metal and ambichiral dielectric medium. Our calculations revealed that there exist five plasmon modes for chiral, trigonal, and tetragonal structures; three plasmon modes for pentagonal structure; two plasmon modes for hexagonal structure; and one plasmon mode for dodecagonal structure that propagate with different phase speeds. The obtained results showed that only one plasmon mode occurs at all pitches, while other modes exist at some of the pitches of anisotropic chiral and ambichiral dielectric mediums. The time-averaged Poynting vector versus the thickness of metal film confirmed that the energy of photons of incident light is transferred to surface plasmon polariton quasiparticles and the surface plasmon polariton wave is localized at the interface of metal and ambichiral dielectric medium. 相似文献
2.
Optical transmission properties of multilayered ultra-thin metal gratings are numerically studied. The transmission spectrum
has a broad stop-band with extremely low transmittance compared to that of a single-layer one for TM polarization. The stop-band
is shown to be formed by multiple-interference tunneling and various plasmon resonance processes in ultra-thin-metal and dielectric
multilayers. That is on the transmission background of non-apertured metal/dielectric multilayer structures that have low
transmission in the long-wavelength range due to destructive multiple-interference tunneling, the transmission is further
suppressed in the stop-band by plasmon resonances in the top metal/dielectric layers, e.g., the anti-symmetric bound surface
plasmon mode in the ultra-thin metal layer and the gap surface plasmon mode in the metal-sandwiched dielectric layer. High
transmission beyond the stop-band is due to coupled gap surface plasmon mode in the entire multilayer structures. Applications
of the optical properties of the multilayered ultra-thin metal gratings are suggested for optical filtering (wavelength or
polarization selective). 相似文献
3.
The surface plasmon resonances of silver nanoshell particles are studied by Green’s function. The nanoshell system of plasmon
resonances results from the coupling of the inner and outer shell surface plasmon. The shift of the nanoshell plasmon resonances
wavelength is plotted against with different dielectric environments, several different dielectric cores, the ratio of the
inner and outer radius, and also its assemblies. The results show that a red- and blue-shifted localized surface plasmon can
be tuned over an extended wavelength range by varying dielectric environments, the dielectric constants and the radius of
nanoshell core respectively. In addition, the separation distances, the distribution of electrical field intensity, the incident
directions and its polarizations are also investigated. The study is useful to broaden the application scopes of Raman spectroscopy
and nano-optics. 相似文献
4.
A variant of surface plasmon resonance (SPR) spectroscopy has been developed that involves a coupling of plasmon resonances in a thin metal film and waveguide modes in a dielectric overcoating. This new technique is referred to as coupled plasmon-waveguide resonance (CPWR) spectroscopy. It combines a greatly enhanced sensitivity (due to increased electromagnetic field intensities at the dielectric surface) and spectral resolution (due to decreased resonance linewidths), with the ability to directly measure anisotropies in refractive index and optical absorption coefficient in a dielectric film adsorbed onto the surface of the overcoating. Experimental data obtained with an egg phosphatidylcholine bilayer are presented to document these properties. 相似文献
5.
The tunneling of surface plasmon waves between two slabs of dielectric prisms superposed on the metal surface is studied. The prism with the incident surface plasmon wave is superposed by a stack of graphene sheets. The analytical theory is built to connect the Fermi energy of graphene with the Goos-Hänchen shift of the transmitted surface plasmon waves. The obtained results may be useful for developing integral switching devices on the basis of surface plasmon polaritons. 相似文献
6.
Radiation damping of surface plasmon oscillations in metallic nanoparticles is proportional to their volume. For relatively large particles, this canal dominates the other mechanisms of relaxation and becomes the main limiting factor for spectral sensitivity of nanoparticles. In this communication, we consider metallic nanoshell with the dielectric core and calculate the radiation damping rate of surface plasmon oscillations, depending on the geometry and dielectric constants of the surrounding environment and the core. It is shown that surface plasmon radiation damping in nanoshell is suppressed by several orders of magnitude as compared to the solid particle of the same outer radius. This effect is conditioned by strong redshift of surface plasmon frequencies with the decrease of shell thickness. It is also demonstrated that the radiation damping rate of core–shell particle is highly sensitive with respect to the refractive index of surrounding media. 相似文献
7.
We obtained experimentally strong plasmon interactions between localized surface plasmon with delocalized surface plasmon
polaritons in a new nanosystem of silver semishells island film arrays arranged as a closed-packing structure coupled to an
adjacent thin silver film. We show that plasmon interactions for such a nanosystem exhibits two pronounced resonances and
interpret the coupling in terms of Fano resonances. The higher energy resonance is identified as a symmetric hybridization
mode between localized plasmon resonances in the island semishell array and surface plasmon polaritons in the metal film and
while the lower energy resonance is identified as a corresponding anti-symmetric hybridization mode. Increasing the size of
the particle arrays enhances and red shifts the resonances. We show that adding a dielectric spacer between the semishell
island array and the metal film results in a red shifting of the resonances and introduce an additional high energy spectral
peak. The effect of the spacer layer is interpreted as a reduced hybridization and the generation of additional localized
surface plasmon resonances. 相似文献
8.
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
9.
We present a new approach to surface plasmon microscopy with high refractive index sensitivity and spatial resolution that is not limited by the propagation length of surface plasmons. It is based on a nanostructured metallic sensor surface supporting Bragg-scattered surface plasmons. We show that these non-propagating surface plasmon modes are excellently suited for spatially resolved observations of refractive index variations on the sensor surface owing to their highly confined field profile perpendicular to as well as parallel to the metal interface. The presented theoretical study reveals that this approach enables reaching similar refractive index sensitivity as regular surface plasmon resonance (SPR) microscopy and offers the advantage of improved spatial resolution when observing dielectric features with lateral size <10???m for the wavelength around 800?nm and gold as the SPR-active metal. This paper demonstrates the potential of Bragg-scattered surface plasmon microscopy for high-throughput SPR biosensing with high-density microarrays. 相似文献
10.
Because of the interaction between dipole resonances of the inner gold sphere and the outer gold shell, gold-dielectric-gold
multishells with sub-50 nm diameter may at most have three hybridization modes of surface plasmon resonance (SPR). Theoretical
calculations based on quasi-static theory indicate that there are blending and splitting of SPR bands in the absorption spectra,
which makes the number of absorption peak tunable by changing the radius of inserted gold sphere, thickness of gold shell,
dielectric constant of middle dielectric shell or outer environment. The two absorption peaks at longer wavelength, which
correspond to the hybridization from the bonding shell plasmon and the sphere plasmon, are usually intense and well tunable.
The absorption peak at shorter wavelength, which corresponds to the symmetric coupling between the anti-bonding shell plasmon
and the sphere plasmon, is relative weak and only occurs with large dielectric constant of the middle shell, small dielectric
constant of the outer surrounding, large inner radius of the gold shell, and small radius of the inner gold sphere. Furthermore,
the physical origin of these plasmon hybridizations in gold-dielectric-gold multishells nanostructure has also been illuminated
by analyzing the local electric field distributions. 相似文献
11.
The detection performance of conventional surface plasmon resonance (SPR) biosensors is limited to a 1 pg/mm(2) surface coverage of biomolecules, and consequently, such sensors struggle to detect the interaction of small molecules in low concentrations. The present study is attempted to propose the use of a novel SPR biosensor with Au nanoclusters embedded in a dielectric film to achieve a 10-fold improvement in the resolution performance. A co-sputtering method utilizing a multi-target sputtering system is used to fabricate the present dielectric films (SiO(2)) with embedded Au nanoclusters. It is shown that the sensitivity of the developed SPR biosensor can be improved by adjusting the size and volume fraction of the embedded Au nanoclusters in order to control the surface plasmon effect. The present gas detection and DNA hybridization experimental results confirm that the proposed Au nanocluster-enhanced SPR biosensor provides the potential to achieve an ultrahigh-resolution detection performance of approximately 0.1 pg/mm(2) surface coverage of biomolecules. 相似文献
12.
The influence of different near-field optical (near-field scanning optical microscopy) probes on the imaging of surface plasmon polaritons propagating on thin metal films is investigated. Metal-coated fiber probes exhibit a suppression of the measured plasmon signal close to the metal film surface and increased local scattering of the plasmon field. Purely dielectric fiber probes are shown to be largely free of these effects. 相似文献
13.
New method of experimental determination of local field enhancement at metal nanoparticles is suggested. It uses surface plasmon
as a probe. Alternating-sign shift of surface plasmon resonance in copper nanoparticles incorporated in silica matrix has
been observed under irradiation by intense femtosecond laser pulse. The red shift of plasmon observed during the action of
pump pulse is interpreted as a result of change of dielectric constant of silica matrix due to optical Kerr effect in electric
field of pump pulse enhanced in a vicinity of metal nanoparticles. The field enhancement factor is estimated from the value
of the observed red shift of plasmon resonance. 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.
Metal-dielectric-graphene hybrid heterostructures based on oxides Al2O3, HfO2, and ZrO2 as well as on complementary metal–oxide–semiconductor compatible dielectric Si3N4 covering plasmonic metals Cu and Ag have been fabricated and studied. We show that the characteristics of these heterostructures are important for surface plasmon resonance biosensing (such as minimum reflectivity, sharp phase changes, resonance full width at half minimum and resonance sensitivity to refractive index unit (RIU) changes) can be significantly improved by adding dielectric/graphene layers. We demonstrate maximum plasmon resonance spectral sensitivity of more than 30,000 nm/RIU for Cu/Al2O3 (ZrO2, Si3N4), Ag/Si3N4 bilayers and Cu/dielectric/graphene three-layers for near-infrared wavelengths. The sensitivities of the fabricated heterostructures were?~?5–8 times higher than those of bare Cu or Ag thin films. We also found that the width of the plasmon resonance reflectivity curves can be reduced by adding dielectric/graphene layers. An unexpected blueshift of the plasmon resonance spectral position was observed after covering noble metals with high-index dielectric/graphene heterostructures. We suggest that the observed blueshift and a large enhancement of surface plasmon resonance sensitivity in metal-dielectric-graphene hybrid heterostructures are produced by stationary surface dipoles which generate a strong electric field concentrated at the very thin top dielectric/graphene layer. 相似文献
16.
In this work, the expanding thermal plasma chemical vapor deposition in combination with radio frequency magnetron sputtering
is used to deposit dielectric/metal multi-layers with controlled size and density of nanoparticles. The multi-layer structure
serves the purpose of increasing the nanoparticle number density, without changing the metal particle size, shape and the
interparticle distance. The possibility of independently tuning and, therefore, controlling the nanoparticle size and number
density allows developing surface plasmon resonance-based deep-colored coatings. The influence of the number of layers, metal
surface area coverage, and thickness of the dielectric layer on the multi-layer nanostructure and on the developed color is
presented here in detail. The nanoparticle size and distribution have been measured by transmission electron microscopy. Rutherford
back-scattering and infra-red transmission spectroscopy have been used to determine the metal surface coverage and the film
chemistry, respectively. Optical properties of the nano-composite layers have been investigated by UV-VIS spectroscopy and
exhibit an increase in amplitude of the plasmon absorption spectra at a fixed plasmon resonance frequency with an increase
in the number of layers. 相似文献
17.
We consider the formation of the surface plasmon polariton (SPP) mode in the structure with a metallic torus and a metallic
flat surface separated by a dielectric medium. The energy of the wave field is mainly concentrated in the dielectric medium
at the vicinity of the minimum thickness of the gap between the metallic surfaces. The dependence of the resonant frequency
on parameters of the structure was determined. The strongly localized SPP mode in the transverse direction contributes to
the increase in the Purcell factor that is crucial for enhancement of the spontaneous emission rate. 相似文献
18.
We theoretically study mode hybridization and interaction among surface plasmon polariton Bloch wave mode, Fabry–Perot cavity mode, and waveguide mode within a plasmonic cavity composed by two parallel planar bimetallic gratings. Four hybridized modes result from mode hybridization between surface plasmon polariton Bloch wave modes on the two gratings are observed. By changing the dielectric environment, mode hybridization behavior can be manipulated. Importantly, waveguide-plasmon polariton mode due to hybridization between grating supported surface plasmon polariton Bloch wave mode and cavity supported waveguide mode is observed. We demonstrate that surface plasmon polariton Bloch wave mode and Fabry–Perot cavity mode with the same mode symmetry can interact by presenting an anticrossing behavior, which can be controlled by laterally shifting one grating with respect to the other that causes a phase difference shift of the two involving modes. The proposed plasmonic cavity offers potentials for subwavelength lithography, tunable plasmonic filter, and controllable light-matter interaction. 相似文献
19.
We report experimentally the remote excitation surface plasmon and consequent enhancement of surface-enhanced Raman scattering
(SERS) using evanescent wave propagating in quasi-one-dimensional (Q1D) MoO 3 ribbon dielectric waveguide. The propagating dielectric waveguide along Q1D MoO 3 ribbon is realized experimentally, when the 632.8 nm laser radiates on the one side edge of Q1D MoO 3 ribbon. The remote excitation SERS spectra-enhanced by chemical and electromagnetic field mechanisms are measured, respectively,
where silver (Ag) nanoparticles are excited by electromagnetic field after propagating 7.3 μm in the ribbon. The chemical
mechanism for the remote excitation SERS is contributed from the charge transfer between the analyte molecule and MoO 3 ribbon. The electromagnetic field mechanism for the remote excitation SERS arises from the energy conversion from the propagating
dielectric waveguide to the surface plasmon of Ag nanoparticles on the Q1D MoO 3 ribbon. It is important to reveal the mechanism of energy conversion from the propagating dielectric waveguide to the surface
plasmon for potential applications in micro- and nanoscale devices. 相似文献
20.
The localized surface plasmon resonances of multilayered nanostructures are studied using finite difference time domain simulations and plasmon hybridization method. Concentric metal–dielectric–metal (MDM) structure with metal core and nanoshell separated by a thin dielectric layer exhibits a strong coupling between the core and nanoshell plasmon resonance modes. The coupled resonance mode wavelengths show dependence on the dielectric layer thickness and composition of core and outer layer metal. The aluminum-based MDM structures show lower plasmon wavelength compared with Ag- and Au-based MDM nanostructures. The calculated refractive index sensitivity (RIS) factor is in the order Ag–Air–Ag>Au–Air–Au>Al–Air–Al for monometallic multilayered nanostructures. Bimetallic multilayered nanostructures support strong and tunable plasmon resonance wavelengths as well as high RIS factor of 510 nm/refractive index unit (RIU) and 470 nm/RIU for Al–Air–Au and Ag-Air-Au, respectively. The MDM structures not only exhibit higher index sensitivity but also cover a wide ultraviolet–near-infrared wavelengths, making these structures very promising for index sensing, biomolecule sensing, and surface-enhanced Raman spectroscopy. 相似文献
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