Guided Plasmon Modes of a Graphene-Coated Kerr Slab

We study analytically propagating surface plasmon modes of a Kerr slab sandwiched between two graphene layers. We show that some of the modes that propagate forward at low field intensities start propagating with negative slope of dispersion and positive flux of energy (fast-light surface plasmons) when the field intensity becomes high. We also discover that our structure supports an additional branch of low-intensity fast-light guided modes. The possibility of dynamically switching between the forward and the fast-light plasmon modes by changing the intensity of the excitation light or the chemical potential of the graphene layers opens up wide opportunities for controlling light with light and electrical signals on the nanoscale.     

Substrate-Independent Lattice Plasmon Modes for High-Performance On-Chip Plasmonic Sensors

We systematically study the lattice plasmon resonance structures, which are known as core/shell SiO₂/Au nanocylinder arrays (NCAs), for high-performance, on-chip plasmonic sensors using the substrate-independent lattice plasmon modes (LPMs). Our finite-difference time-domain simulations reveal that new modes of localized surface plasmon resonances (LSPRs) show up when the height-diameter aspect ratio of the NCAs is increased. The height-induced LSPRs couple with the superstrate diffraction orders to generate the substrate-independent LPMs. Moreover, we show that the high wavelength sensitivity and the narrow linewidth of the substrate-independent LPMs lead to the plasmonic sensors with high figure of merit (FOM) and high signal-to-noise ratio (SNR). In addition, the plasmonic sensors are robust in asymmetric environments for a wide range of working wavelengths. Our further study of both far- and near-field electromagnetic distribution in the NCAs confirms the height-enabled tunability of the plasmonic “hot spots” at the sub-nanoparticle resolution and the large field enhancement in the substrate-independent LPMs, which are responsible for the high FOM and SNR of the plasmonic sensors.     

Four Terahertz Plasmon Modes of Hole Gas in Monolayer MoS2

Plasmonics - We investigate on the terahertz (THz) plasmons of hole gas in monolayer MoS2 in the presence of spin-orbit interactions (SOIs) under the random phase approximation. The study shows...     

Large Optical Nonlinearity of Surface Plasmon Modes on Thin Gold Films

We investigate the optical nonlinear effects of a long-range surface plasmon polariton mode propagating on a thin gold film. These effects may play a key role in the design of future nanophotonic circuits as they allow for the realization of active plasmonic elements. We demonstrate a significant enhancement of the transmission on a timescale below a millisecond as well as a phase shift exceeding 2π already for modest peak powers of 150 mW. On the contrary, slow effects suppress the transmission on a millisecond timescale.     

Tunable Localized Hybrid Plasmon Modes and Fano Resonances in Au Core-Semishell

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...     

Analysis of Mid-Infrared Surface Plasmon Modes in a Graphene-Based Cylindrical Hybrid Waveguide

A graphene-based cylindrical hybrid surface plasmon polariton waveguide, composed of a silicon nanowire core surrounded by a silica layer and then a graphene layer, is investigated using the finite-difference time-domain method. The analytical solutions and the numerical simulation show that an ultra-small mode area and a large propagation length can be achieved with this waveguide. Utilizing the perturbation theory of coupled mode, we demonstrate that the six lowest-order coupling modes originate from the coupling of the three lowest-order single-waveguide modes, and the m?=?1 order yy-coupling mode possesses the maximum coupling length and the minimum crosstalk. This waveguide can be used for photonic integrated circuits in the mid-infrared range.     

On the Surface Plasmon Resonance Modes of Metal Nanoparticle Chains and Arrays

A method for estimating the surface plasmon resonance modes of metal nanoparticle chains and arrays within a multilayered medium is proposed. In this fully retarded point-dipole method, an inhomogeneous background is replaced with a homogeneous one, based on an effective refractive index approximation. The proposed method includes the effects of retardation, radiative damping, and dynamic depolarization due to the finite size of the nanoparticles. The use of diagonal terms of dyadic Green’s functions and different polarizability coefficients along the semi-axes of ellipsoidal nanoparticles provides a complete set of both longitudinal and transverse resonance modes. Numerical results are compared with experimental results found in the literature.     

Ascertaining Plasmonic Hot Electrons Generation from Plasmon Decay in Hybrid Plasmonic Modes

Plasmonics - In the propagating process along metal surface, surface plasmon polaritons (SPPs) mainly decay into thermal loss or release into photons, while a part of them were converted into...     

Efficient Extraction of Fluorescence Emission Utilizing Multiple Surface Plasmon Modes from Gold Wire Gratings

We demonstrate directional enhanced fluorescence emission from fluorophores located above gold wire gratings. In contrast to previous studies on corrugated films, efficient coupling was recorded for multiple plasmon modes associated with both the active and substrate side of the wires. This difference is likely due to the subtle differences in how light interacts with corrugated films versus metal films with periodic subwavelength slots. For corrugated films, coupling between modes on opposite sides of the grating are out of phase, and therefore plasmon modes on the opposite side of the grating are only weakly excited. For wire gratings, transmission and reflection features have been modeled well with a dynamical diffraction model that includes surface plasmons, which allows for efficient coupling to surface plasmon modes on both sides of the grating. We also compared the two mechanisms for fluorescent enhancement, namely the intense electromagnetic field associated with surface plasmons and excited fluorophores radiating via surface plasmon modes. We found the latter mechanism clearly dominant.     

Surface Plasmon Polariton Modes at Interface of a Metal and an Ambichiral Sculptured Thin Film

The excitation of surface plasmon polariton (SPP) at interface of a metal and an ambichiral sculptured thin film was theoretically investigated in the Kretschmann configuration using the transfer matrix method. The dependence of SPP modes for a P polarization plane wave on the incident angle of light and the angle of rise of nanocolumns of ambichiral dielectric medium was reported. We found that multiple SPP modes are excited at the interface of metal and ambichiral dielectric medium. The results of phase speed as a function of pitch showed only that a SPP mode can be excited at all pitches.     

Deep Subwavelength Confinement of Mid-infrared Plasmon Modes by Coupling Graphene-Coated Nanowire with a Dielectric Substrate

In this paper, we report the realization of highly confined mid-infrared plasmon modes by coupling freestanding graphene-coated nanowire with a dielectric substrate. It is shown that the presence of a nearby dielectric substrate not only breaks the azimuthal symmetry of the plasmon modes but also has a strong impact on the coupling and hybridization of these modes. The degree of interactions with the substrate depends on the permittivity of the substrate, the key structural parameters of the nanowire, the operation frequency and chemical potential of graphene, as well as the gap distance between the nanowire and supporting substrate. It is found that compared to freestanding case, using a high-index substrate and adjusting the gap distance can result in the following benefits: (i) an ultra-small mode area and a long propagation length can be realized simultaneously, (ii) a stronger field enhancement in the low-index gap region and improved figure of merit can be achieved, and (iii) a huge reduction in the crosstalk can be made which is crucial for the realization of high-density integrated nanophotonic devices.     

Ring Gap Resonance Modes on Disk/Film Coupling System Caused by Strong Plasmon Interaction

Ring modes with large wave vectors cannot be easily excited on a single disk by the plane wave illumination with the polarization parallel to the disk interface. In this work, we show that special antisymmetric ring gap modes on the surface of the disk in close proximity to the metallic thin film can be excited in the visible light region of the electromagnetic spectrum. In the presence of the film, the strong plasmon interaction between disk and film causes ring gap modes to have lower energies and be more easily excited. We apply the plasmon hybridization method to illustrate the ring gap modes arising from the interaction between the localized disk plasmons and the continuum surface plasmons. The calculated hybridization data show good agreement with the results of finite element simulations. The excitation of ring gap modes provides further insight into the strong coupling of plasmons and the design of novel nanostructures.

     

Systematic Evolution of Resonant Coupling Behavior Between Surface Plasmon Polaritons and Multi-waveguide Modes in Metal-Dielectric Multi-layers

Plasmonics - A multi-layer structure consisting of metal and dielectric layers which allows coupling between surface plasmon polaritons and waveguide modes is studied by calculating reflectivity...     

The Surface Plasmon Resonance Polarizing Management in Helical Microstructure Fiber

Plasmonics - Surface plasmon resonance (SPR) is a useful phenomenon in many application fields, such as communication and sensing field. In this paper, for the first time, the SPR phenomenon in...     

Co-existence of Radiative and Non-Radiative Surface Plasmon Resonance Modes: Power Balance and Influence of Film Morphology

Plasmonics - The power balance and conditions of co-existing radiative and non-radiative surface plasmon resonance modes have been exploited at the metal film-water interface. Angular (AIM) and...     

Light Amplification with Low-Gain Material: Harvesting Harmonic Resonance Modes of Surface Plasmon Polaritons on a Magnetic Meta-Surface

We theoretically show that it is feasible to utilize harmonic resonance modes of surface plasmon polaritons on a magnetic meta-surface for light amplification with low-gain material. The required threshold and optimal gain strength for active layer can be substantially reduced to about one-tenth as compared with those utilizing fundamental resonance modes. The findings provide a simple and practical metamaterial approach for light amplification with most of the existing active media.     

不同管理模式在日间手术中的应用实践

目的 深入分析探究“日间手术”临床实践中管理模式。方法 通过回顾总结我院南北部采用不同的（集中化与分散化）管理模式开展“日间手术”实践经验,对服务的效率、病人满意度等样本数据进行客观的进行类比分析。结果 统计数据及分析结果表明“日间手术”采用集中化管理模式的南部在服务效率比、病人满意度方面大幅提升。结论 “日间手术”集中化管理模式可以大大提高医疗服务的效率比、医疗质量与安全得以最大保障。     

Subradiant,Superradiant Plasmon Modes and Fano Resonance in a Multilayer Nanocylinder Array Standing on a Thin Metal Film

The optical properties of a novel nanostructure consisting of a hexagonal array of aligned vertically three-layered metal-dielectric-metal nanodisks on a silver film are theoretically studied through the finite-difference time-domain method. The novel nanostructure exhibits three obvious optical transmission bands due to the excitation of subradiant plasmon modes, superradiant plasmon modes, and Fano resonances. Surface plasmon polaritons of the underlying Ag film also play a significant role on these three optical transmission bands via coupling with localized surface plasmons of nanodisk pairs. Moreover, the nanostructure also exhibits a good tunability of optical response by modifying the sizes of cylinders, the thickness of underlying metal film, and the dielectric constant of middle layer. These results demonstrate the nanostructure with great advantages in optical sensors and filters.

     

Tailoring Plasmon Lifetime in Suspended Nanoantenna Arrays for High-Performance Plasmon Sensing

We demonstrate significantly longer plasmon lifetime and stronger electric field enhancement by lifting the nanoantenna arrays above the substrate by dielectric nanopillars. The role of the pillar is to offer a more homogeneous dielectric background allowing stronger diffraction coupling among plasmonic nanoantennas leading to a Fanolike asymmetric lineshape. It is found that the electric fields around the nanoantennas can be greatly enhanced when the Fanolike resonance is excited, and a 4.2 times enhancement is achieved compared with the pure resonance in individual nanoantennas. Furthermore, only a collective surface mode with its electric fields of the same direction as the induced electric moment in the nanoantennas could mediate the excitation of such a Fanolike resonance. More importantly, the sensitivity and the figure of merit (FOM) of this plasmonic structure can reach as high as 900 nm/RIU and 53, respectively. Our study offers a new, simple, and efficient way to design the plasmonic systems with desired electric field enhancement and spectral lineshape for different applications.