Abstract:We theoretically investigate the optical properties of a nanostructure consisting of the two identical and symmetrically arranged crisscrosses. A plasmonic Fano resonance is induced by a strong interplay between bright mode and dark modes, where the bright mode is due to electric dipole resonance while dark modes originate from the magnetic dipole induced by LC resonances. In this article, we find that the electric field “hotspots” corresponding to three different wavelengths can be positioned at the same spat… Show more
“…This results in studying interesting plasmonic properties such as a shift in plasmonic resonances, hybrid plasmon modes, sizeable local-field enhancement (hot-spot generation), etc. Numerous studies demonstrating such large field local enhancement have been reported based on various nanostructures such as dimers, nanoparticles on a metallic film, and so on [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Of these, the nanoparticles coupled with film design has attracted significant interest recently [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ].…”
We present a computational study of the near-field enhancement properties from a plasmonic nanomaterial based on a silver nanoparticle on a gold film. Our simulation studies show a clear distinguishability between nanoparticle mode and gap mode as a function of dielectric layer thickness. The observed nanoparticle mode is independent of dielectric layer thickness, and hence its related plasmonic properties can be investigated clearly by having a minimum of ~10-nm-thick dielectric layer on a metallic film. In case of the gap mode, the presence of minimal dielectric layer thickness is crucial (~≤4 nm), as deterioration starts rapidly thereafter. The proposed simple tunable gap-based particle on film design might open interesting studies in the field of plasmonics, extreme light confinement, sensing, and source enhancement of an emitter.
“…This results in studying interesting plasmonic properties such as a shift in plasmonic resonances, hybrid plasmon modes, sizeable local-field enhancement (hot-spot generation), etc. Numerous studies demonstrating such large field local enhancement have been reported based on various nanostructures such as dimers, nanoparticles on a metallic film, and so on [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Of these, the nanoparticles coupled with film design has attracted significant interest recently [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ].…”
We present a computational study of the near-field enhancement properties from a plasmonic nanomaterial based on a silver nanoparticle on a gold film. Our simulation studies show a clear distinguishability between nanoparticle mode and gap mode as a function of dielectric layer thickness. The observed nanoparticle mode is independent of dielectric layer thickness, and hence its related plasmonic properties can be investigated clearly by having a minimum of ~10-nm-thick dielectric layer on a metallic film. In case of the gap mode, the presence of minimal dielectric layer thickness is crucial (~≤4 nm), as deterioration starts rapidly thereafter. The proposed simple tunable gap-based particle on film design might open interesting studies in the field of plasmonics, extreme light confinement, sensing, and source enhancement of an emitter.
“…In order to promote the application and development of SEHRS technology in different fields, it is particularly important to develop SEHRS substrates which can enhance the incident light and the scattered light in the same spatial locations. In fact, for surface enhanced nonlinear optical processes, the plasmonic substrate with multiple resonances at the same spatial locations is indispensable 23 , 24 . Figure 1 Energy-level diagrams for Raman scattering, surface-enhanced Raman scattering, hyper-Raman scattering, and surface-enhanced hyper-Raman scattering.…”
Because of the unique selection rule, hyper-Raman scattering (HRS) can provide spectral information that linear Raman and infrared spectroscopy cannot obtain. However, the weak signal is the key bottleneck that restricts the application of HRS technique in study of the molecular structure, surface or interface behavior. Here, we theoretically design and investigate a kind of plasmonic substrate consisting of Ag nanorices for enhancing the HRS signal based on the electromagnetic enhancement mechanism. The Ag nanorice can excite multiple resonances at optical and near-infrared frequencies. By properly designing the structure parameters of Ag nanorice, multi- plasmon resonances with large electromagnetic field enhancements can be excited, when the “hot spots” locate on the same spatial positions and the resonance wavelengths match with the pump and the second-order Stokes beams, respectively. Assisted by the field enhancements resulting from the first- and second-longitudinal plasmon resonance of Ag nanorice, the enhancement factor of surface enhanced hyper-Raman scattering can reach as high as 5.08 × 109, meaning 9 orders of magnitude enhancement over the conventional HRS without the plasmonic substrate.
“…The plasmons behave like photons in conventional lasers with a plasmonic cavity which helps spaser to break the diffraction limit [ 4 , 5 ]. The near field enhancement produced by nanostructures have a vast range of applications such as sensing [ 6 ], perfect light absorption [ 7 ], switching and nanocircuits [ 8 ], light speed manipulation and dispersion [ 9 ], cloaking and imaging [ 10 ], focusing and lasing [ 11 ], enhanced non-linear effect [ 12 ], surface-enhanced Raman scattering [ 13 ] and holograms. Coherent active plasmon-based structures open paths for the expansion of SP-based applications and investigation of the matter-light interactions at the nanoscale.…”
We theoretically demonstrated a class of plasmonic coupled elliptical nanostructure for achieving a spaser or a nanolaser with high intensity. The plasmonic ellipse is made up of gold film substrate. The proposed structure is then trialed for various light polarizations, moreover, a simple elliptical nanostructure has been chosen primarily from which different cases have been formed by geometry alteration. The structure supports strong coupled resonance mode i.e. localized surface plasmon (LSP). The localized surface plasmon resonance (LSPR) of the investigated system is numerically examined using the finite-element method (FEM). The calculations showed that the LSPR peaks and the local field intensity or near field enhancement (NFE) of the active nanosystem can be amplified to higher values by introducing symmetry-breaking techniques in the proposed ellipse and its variants. The coupled nanostructure having different stages of wavelengths can be excited with different plasmonic resonance modes by the selection of suitable gain media. In addition, a small-sized nanolaser with high tunability range can be developed using this nanostructure. The spaser phenomena are achieved at several wavelengths by changing light polarization and structure alteration methods. Giant localized field enhancement and high LSPR values enable the proposed model to be highly appealing for sensing applications, surface-enhanced Raman spectroscopy, and much more.
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