Jinna He

Due to the topological charge-independent doughnut spatial structure as well as the association of orbital angular momentums, perfect vortex beams promise significant advances in fiber communication, optical manipulation and quantum optics. Inspired by the development of planar photonics, several plasmonic and dielectric metasurfaces have been cons...

Resonant plasmonic nanostructures have attracted much attention due to their exotic optical properties. In this work, we numerically investigate single- and dual-gap ring structures, respectively, and they can be used for refractive index sensing by exciting the gap plasmon mode with sharp resonance spectra. The dual-gap ring plasmonic sensor shows...

Excitation of ultraviolet (UV) range plasmon resonance with high quality (Q)-factor has been significantly challenging in plasmonics because of inherent limitations in metals like Au and Ag. Herein, we theoretically investigated UV-visible range plasmons in the topological insulator Bi1.5Sb0.5Te1.8Se1.2 (BSTS) nanosphere and nanoshell. In contrast...

Metasurfaces, planar arrays of subwavelength optical phase shifters, show unprecedented superiority to convention bulk optical elements in many applications. Until now, most of metasurfaces work at frequencies from the microwave to the visible; material challenges (lack of media supporting resonant responses at higher frequencies) have hampered the...

Plasmonic nanostructures have important applications for surface-enhanced Raman chips, optical sensors, perfect absorbers, and so on. In this paper, we theoretically investigate the optical properties of a T-shaped dimer (TD) nanostructure and a TD with nanowire loads (TD/NL) nanostructure. By depositing the NLs around the TD, the optical property...

We theoretically demonstrate a kind of plasmon coupled cavity to achieve a nanolaser with high intensity and low threshold. The plasmon cavity is composed of the gold film substrate and gold disk array, which supports two strong coupled resonance modes (i.e. surface plasmon polariton (SPP) and localized surface plasmon (LSP)). Compared with the nan...

We propose a kind of gradient metasurface based on graphene apertures for wavefront control of terahertz linear polarized waves. By carefully designing the geometric dimensions of the graphene rectangular apertures, the proposed metasurface can realize arbitrary reflection, carpet cloak and reflective focusing, respectively. The simulation results...

A plasmonic substrate providing high, reproducible and stable Raman signals should be highly desirable for the development of surface enhanced coherent anti-Stokes Raman spectroscopy (SECARS). In this work, we theoretically present a design of SECARS substrate consisting of five different-sized gold nanodisks and investigate its enhancement propert...

Since the nucleation and growth of clusters is usually a non-equilibrium condensation process, a distribution of structural isomers for a given cluster size may be encountered even under the same conditions. In this work, molecular dynamics simulations are performed on sets of molten clusters of Cu309 to study their structures at low temperatures w...

Surface plasmons supported by various metallic nanostructures have given rise to several significant breakthroughs in the field of integrated photonic devices due to its ability to effectively confine and enhance optical field in subwavelength volume. In particular, the demand to actively control optical responses of plasmonic systems becomes urgen...

Plasmon-induced transparency (PIT), an analog of electromagnetically induced transparency, originates from destructive interference of plasmonic resonators with different quality factors and brings about the extreme dispersion within the narrow transparency window, promising remarkable potential for slow light, nonlinear optics and biochemical sens...

We proposed a facile green synthesis system to synthesize large-scale Ag hemi-mesoparticles monolayer on Cu foil. Ag hemi-mesoparticles have different surface morphologies on their surfaces, including ridge-like, meatball-like, and fluffy-like shapes. In the reaction, silver nitrate was reduced by copper at room temperature in dimethyl sulfoxide vi...

Surface enhanced coherent anti-Stokes Raman scattering (SECARS) is a sensitive tool and promising for single molecular detection and chemical selective imaging. However, the enhancement factors (EF) were only 10~100 for colloidal silver and gold nanoparticles usually used as SECARS substrates. In this paper, we present a design of SECARS substrate...

Plasmonic metallic nanostructures have been demonstrated an effective way to enhance the light emission efficiency in LEDs. Here, we propose a design of white LEDs that combining dielectric silicon nanopillar array in the color-converting layer. By investigating theoretically the guided mode caused by the nanopillar array-waveguide system, we demon...

We theoretically investigate the gain-assisted plasmonic analog of electromagnetically induced transparency (EIT) in a novel planar metamaterial, whose unit cell consists of two perpendicularly connected metallic bars, forming a ‘T’ configuration. An EIT-like resonance can be achieved by introducing symmetry breaking into its shape. The results sho...

We demonstrate theoretically an analogue of electromagnetically induced transparency (EIT) at visible frequencies in an all-dielectric metamaterial-waveguide (ADMW) system that consists of a two-dimensional silicon nanopillar array on top of a dielectric slab waveguide. By varying the lattice period of the array, we show that the transmission featu...

Nanohole arrays or individual nanohole oligomers in metallic films have attracted intense attention due to their unique optical properties such as extraordinary optical transmission or Fano resonance. However, the nanohole oligomer array still remains largely unexplored. In this work, we numerically investigate the heptamer-hole arrays in an optica...

A novel plasmonic metamaterial consisting of the solid (bar) and the inverse (slot) compound metallic nanostructure for electromagnetically induced absorption (EIA) is proposed in this paper, which is demonstrated to achieve an ultra-narrow absorption peak with the linewidth less than 8 nm and the absorptivity exceeding 97% at optical frequencies....

We propose a novel metasurface that supports an analogue of electromagnetically induced transparency (EIT) at optical frequencies. With the aid of polarization-controlled coupling of bright and dark modes, on-off amplitude modulation of the EIT-like transparency window is achieved by changing the incident polarization orientation, allowing for an a...

Ag-Fe3O4 nanocomposites were synthesized by the redox reaction between Ag2O and Fe(OH)(2) in the absence of additional reductant at moderate temperature and atmospheric condition. The as-synthesized Ag-Fe3O4 nanocomposites are assembled into an orderly arrayed SERS substrate holding clean and reproducible properties with an applied external magneti...

Polyvinylpyrrolidone (PVP)-protected silver nanostructures of various shapes, including nanocubes, nanospheres, and hybrid shapes with nanospheres and nanorods, on the surface of glass or Si substrates (PVP-Ag films) are prepared by using electrostatic self-assembly. With 4-mercaptobenzoic acid (4-MBA) as a probe molecule, it is demonstrated that t...

In this paper, based on the constructive interference of plasmonic dipolar and quadrupolar modes, a classical analogue of electromagnetically induced absorption (EIA) is demonstrated theoretically in a stacked metamaterial consisting of a short metal strip (which acts as a bright resonator) and a long metal strip (acting as a dark resonator), which...

Ag nanocubes (NCs)/4-aminothiophenol (p-ATP)/smooth platinum (Pt) film (Ag-NCs @ p-ATP/Pt) sandwich structure is created for surface enhanced Raman scattering (SERS). The proposed sandwich structure is shown to exhibit better performance than the Ag-NCs only as SERS substrate. The dependence of the Raman signal intensity on the thickness of the Pt...

The resonance amplification of out-of-plane lattice plasmons (OLPs) in gain-assisted 2D metallic nanoparticle (NP) arrays is investigated theoretically. Due to the angle-dependent near-field optical properties, the gain threshold of OLPs-based spaser can be controlled by adjusting the angle of incident light. OLPs are demonstrated to exhibit lower...

A novel planar plasmonic metamaterial for electromagnetically induced transparency and slow light characteristic is presented in this paper, which consists of nanoring and nanorod compound structures. Two bright modes in the metamaterial are induced by the electric dipole resonance inside nanoring and nanorod, respectively. The coupling between two...

We report that the gain threshold of a core-shell nanoparticle-based spaser can be reduced significantly by offsetting the gain-doped dielectric core within the metallic shell. By investigating the optical cross sections of the reduced symmetry core-shell nanoparticle with different levels of gain, we determined the gain threshold of the asymmetric...

A sharp plasmonic Fano resonance is found to appear in a silver nanorod pair structure with broken length symmetry. It is shown that it arises from strong interference between a narrow plasmon mode of inter-nanorod near-field coupling and broad scattering from the nanorod. The inter-nanorod coupling is the result of the magnetic dipole plasmon reso...

Uniform and reproducible substrates for surface enhanced Raman scattering (SERS) are fabricated by self-assembly of Ag nanoparticles (NPs) on 3-aminopropyltrimethoxysilane (APTES) modified glass. Experimental results indicate that the Ag NPs with a narrow size distribution were assembled as a sub-monolayer which exhibits an excellent SERSactivity....

We theoretically investigate the photonic band gap in one-dimensional photonic crystals with a graded multilayer structure. The proposed structure constitutes an alternating composite layer (metallic nanoparticles embedded in TiO2 film) and an air layer. Regarding the multilayer as a series of capacitance, effective optical properties are derived....

We theoretically investigate the optical properties in one-dimensional graded soft photonic crystals (1D GSPCs). The proposed structure is constituted of the stacked ferrofluids layer and the dielectric layer. Due to the supermagnetic response of the ferromagnetic nanoparticles, they will align in a line under the influence of the initiated magneti...

The optical properties of asymmetric ring structures are investigated theoretically by using the discrete dipole approximation method. The numerical results revealed that this kind of structure can achieve a giant localized field enhancement (LFE, 264) and a high LSPR sensitivity (corresponding FOM, 8.28) in the visible spectrum by Fano resonance,...

Double Fano resonant characteristics are investigated in planar plasmonic structure by embedding a metallic nanorod in symmetric U-shaped split ring resonators, which are caused by a strong interplay between a broad bright mode and narrow dark modes. The bright mode is resulted from the nanorod electric dipole resonance while the dark modes origina...

The performances of thin film solar cells are considerably limited by the low light absorption. Plasmonic nanostructures have been introduced in the thin film solar cells as a possible solution around this issue in recent years. Here, we propose a solar cell design, in which an ultrathin Si film covered by a periodic array of Ag strips is placed on...

A broad-band perfect absorber composing a two-dimensional periodic metal-dielectric-metal sandwiches array on dielectric/metal substrate is designed and numerically investigated. It is shown that the nearly-perfect absorption with a bandwidth of about 50 nm in visible region can be achieved by overlapping of two plasmon resonances: one originating...