Nonlinear resonance-enhanced excitation of surface plasmon polaritons

We theoretically investigate nonlinear resonance-enhanced excitation of surface plasmon polaritons in a metal coated by a one-dimensional photonic crystal. Tunneling modes above the air-light line can be directly excited in this structure. Then, with suitable parameters, photon energy and momentum conservation between the tunneling mode and the surface plasmon polaritons can be realized by means of nonlinear four-wave mixing. Compared with the nonlinear excitation of surface plasmon polaritons in a bulk metal [Phys. Rev. Lett. 103, 266802 (2009)], the conversion efficiency in our structure is noticeably enhanced.     

基于厚金属狭缝阵列的表面等离子激元光刻

提出一种利用厚金属狭缝阵列耦合激发表面等离子激元制作非周期图形的纳米光刻模型.采用时域有限差分电磁场模拟仿真软件研究了厚金属狭缝阵列中表面等离子激元的激发、模式选择以及光刻胶中的光场分布.结果表明,通过优化厚金属狭缝阵列结构参量和匹配介质参量可有效抑制表面等离子激元在光栅狭缝出口处的发散,增加表面等离子激元的穿透深度,...     

Long-range surface plasmon polaritons at THz frequencies in thin semiconductor layers

We present a theoretical investigation of THz long-range surface plasmon polaritons propagating on thin layers of InSb.The metallic behavior of doped semiconductors at THz frequencies allows the excitation of surface plasmon polaritons with propagation and confinement lengths that can be actively controlled.This control is achieved by acting on the free carrier density,which can be realized by changing the temperature of InSb.     

基于厚金属狭缝阵列的表面等离子激元光刻

提出一种利用厚金属狭缝阵列耦合激发表面等离子激元制作非周期图形的纳米光刻模型.采用时域有限差分电磁场模拟仿真软件研究了厚金属狭缝阵列中表面等离子激元的激发、模式选择以及光刻胶中的光场分布.结果表明,通过优化厚金属狭缝阵列结构参量和匹配介质参量可有效抑制表面等离子激元在光栅狭缝出口处的发散,增加表面等离子激元的穿透深度,可获得高分辨率的较大曝光深度的周期和非周期纳米图形,可为纳米激光直写技术提供有益的借鉴.     

Why metallic surfaces with grooves a few nanometers deep and wide may strongly absorb visible light

It is theoretically shown that nanometric silver lamellar gratings present very strong visible light absorption inside the grooves, leading to electric field enhancement of several orders of magnitude. It is due to the excitation of quasistatic surface plasmon polaritons with particular small penetration depth in the metal. This may explain the abnormal optical absorption observed a long time ago on almost flat Ag films. Surface enhanced Raman scattering in rough metallic films could also be due to the excitation of such quasistatic plasmon polaritons in grain boundaries or notches of the films.     

Light scattering by a medium with a spatially modulated optical conductivity: the case of graphene

We describe light scattering from a graphene sheet having a modulated optical conductivity. We show that such modulation enables the excitation of surface plasmon polaritons by an electromagnetic wave impinging at normal incidence. The resulting surface plasmon polaritons are responsible for a substantial increase of electromagnetic radiation absorption by the graphene sheet. The origin of the modulation can be due either to a periodic strain field or to adatoms (or absorbed molecules) with a modulated adsorption profile.     

周期地嵌入电介质球壳的金属表层的表面等离子激元及其与电介质腔体模式的耦合

通过观察金属底板中周期地嵌入电介质球壳的体系的光学吸收性质，研究了表面等离子激元 以及与其他电磁模式的耦合特性.在这种周期结构的金属表面，发现存在两种响应频率，分 别对应于表面等离子激元模式和金属中的电介质腔体模式.在这些响应频率上，可观察到与 它们相对应的吸收峰.由于金属的表面模式不能与平面入射光直接耦合，而腔体模式与平面 入射光和表面等离子激元模式的耦合一般较弱，因而通常情况下这些吸收峰的峰值有限.然 而，通过调整体系中的某些参数，可以使腔体模式和表面模式的频率非常接近，这时二者之 间的耦合强度将大大提高.此时，在相应的频率附近可观察到极强的吸收峰.详细地研究了介 质球壳的物理和几何参数对此共振吸收的影响. 关键词： 腔体模式 表面等离子体模式 共振吸收     

The influence of wire shape on surface plasmon mode distribution

The influence of the nanowire shape on the excitation of surface plasmon polaritons at metallic nanowire arrays is studied numerically. For a system of silver nanowires housed on a polymer substrate, nanowires with rectangular and elliptical cross sections are compared. It was found that in the case of rectangular nanowires the excitation efficiency is higher for surface plasmons at the polymer–metal interface than for surface plasmons at the air–metal interface. Conversely, in the case of elliptical nanowires the air–metal plasmon modes are stronger. Further, it is noted that the nanowire shape directly influences the position of the surface plasmon resonance.     

A Promising Mechanism for Photonic Spin Hall Effect and Refractive Index Sensing: Surface Exciton Polaritons

Surface polaritons are surface electromagnetic waves propagating along the surface of a medium, which play an important role in enhancing the photonic spin Hall effect (SHE). Among them, the successful excitation of surface exciton polaritons (SEPs) often requires cryogenic temperature, which limits their practical applications. In this contribution, a promising mechanism is presented for enhancing the photonic SHE by taking advantage of room-temperature SEPs in a prism-glass-TDBC-air configuration. By depositing the TDBC layer on plasmon active metal, the hybrid polariton, namely, surface plasmon exciton polariton (SPEP) can be observed, which gives rise to the further enhancement of photonic SHE. Furthermore, a refractive index sensor based on SEP (or SPEP) enhanced photonic SHE is proposed with the superior sensing performance. The results pave the way for the realization of giant photonic SHE in this simple and promising method, and offer the opportunity for developing highly sensitive optical sensors.     

金属-介质光栅结构表面等离子体耦合效率的模拟研究

表面等离子体可以将光子局域在金属表面附近, 并形成很强的近场能量密度, 可以大大提高金属表面附近分子的发光效率和光电转换吸收材料的利用率, 从而提高发光器件和光电转换器件的效率. 本文研究了在一维周期性金属-介质混合结构的光栅中表面等离子体激元的耦合条件, 给出了耦合效率随着结构和填充因子的变化, 并证明了在光栅的填充因子较高以至光栅的金属间隔较小时, 光子耦合成为表面等离子体的效率较高, 可以达到94%以上. 关键词： 表面等离子体激元 填充因子 光栅 吸收光谱     

Tapered dielectric structure in metal as a wavelength-selective surface plasmon polariton focuser

Symmetric tapered dielectric structures in metal have demonstrated applications such as the nanofocusing of surface plasmon polaritons, as well as the waveguiding of V-channel polaritons. Yet the fabrication of smooth-surfaced tapered structure remains an obstacle to most researchers. We have successfully developed a handy method to fabricate metal-sandwiched tapered nanostructures simply with electron beam lithography. Though these structures are slightly different from conventional symmetric V-shaped structures, systematic simulations show that similar functionality of surface plasmon polariton nanofocusing can still be achieved. When parameters are properly selected, wavelength-selective nanofocusing of surface plasmon polaritons can be obtained.     

Modification of the photoluminescence anisotropy of semiconductor nanowires by coupling to surface plasmon polaritons

We demonstrate efficient modification of the polarized light emission from single semiconductor nanowires by coupling this emission to surface plasmon polaritons on a metal grating. The polarization anisotropy of the emitted photoluminescence from single nanowires is compared for wires deposited on silica, a flat gold film, and a shallow gold grating. By varying the orientation of the nanowire with respect to the grating grooves, the large intrinsic polarization anisotropy can be either suppressed or enhanced. This modification is interpreted by the appearance of an additional emission channel induced by surface plasmon polaritons and their conversion to p-polarized radiation at the grating.     

损耗对表面等离子体激元压缩态的影响

表面等离子体激元是金属表面电子集体振荡,它以波的形式在金属和介质之间的界面中传播.近期Huck等证明等离子体激元可以处在压缩态,本文利用量子光学的热库理论,研究金波导损耗对表面等离子体激元压缩态的影响,并对Huck等的实验结果给与理论解释. 关键词： 表面等离子体激元 压缩态 热库理论     

Rapid laser prototyping of plasmonic components

Renewed and growing interest in the field of surface plasmon polaritons (SPPs) comes from a rapid advance of nanostructuring technologies. In this paper, we will report on the application of two-photon polymerization (2PP) technique for the fabrication of dielectric SPP-structures, which can be used for localization, guiding, and manipulation of SPPs on a subwavelength scale. This technology is based on nonlinear absorption of near-infrared femtosecond laser pulses. Resolutions down to 100 nm (and even better) are already achievable. Characterization of these structures is performed by leakage radiation microscopy. 2PP allows the fabrication of dielectric waveguides, splitters, and couplers directly on metal surfaces. The dielectric structures on metal films are demonstrated to be very efficient for the excitation of SPPs. Using these structures, one can achieve excitation and focusing of the resulting plasmon field. PACS 42.70.Gi; 42.70.Jk; 42.82.Cr; 71.36.+c; 78.20.-e     

The plasmon–exciton interaction in layered nanostructures with two-dimensional J-aggregates

The transformation of the electronic excitation energy in a plane-layered nanostructure with two-dimensional J-aggregates of a cyanine dye has been studied theoretically. The dependences of the plasmon–exciton interaction energy on the system parameters have been determined. In the case of small values of the Rabi frequency, the rates of nonradiative energy transfer from surface plasmon–polaritons of the metal substrate to molecular excitons of J-aggregates have been calculated in terms of the perturbation theory. The dispersion laws for hybrid plasmon–exciton states have been determined, and it has been shown that the Rabi splitting can range up to 100 meV.     

Hybrid waveguide-surface plasmon polariton modes in a guided-mode resonance grating

We analyze the coupling between surface plasmon polaritons in a metal grating and the guided modes of a dielectric waveguide. Our model structure is a gold wire grating on a slab waveguide made of silicon nitride on silica wafer. The excitation of guided-mode resonances, surface plasmon polariton modes and hybrid waveguide-plasmon modes are observed in numerical simulations. Our experiments verify the existence of the predicted modes. These hybrid modes add significant degrees of freedom in designing structures for plasmonic applications.     

Duality of Spoof Surface Plasmon Polaritons on the Complementary Structures of Ultrathin Metal Films

Complementary metal structures manifest a remarkable scattering feature, known as Babinet's principle. Meanwhile, for surface modes confined to one or two dimensions, the relation between the modes on complementary structures has not been thoroughly studied. Here, spoof surface plasmon polaritons supported on complementary metal films are systematically investigated. The duality of electromagnetism guarantees that these surface modes on complementary metal films possess precisely the same dispersion regardless of the geometry of the grooves, which is confirmed by both numerical simulations and experimental measurements. This work may open another avenue for spoof surface plasmon polaritons in both the theoretical and practical aspects.     

Resolution Enhancement of Plasmonic Sensors by Metal‐Insulator‐Metal Structures

Optical sensors based on surface plasmons have attracted much attention over the past decades owing to the wealth of applications in bio‐ and chemical and gas sensing. In surface plasmon resonance sensors, a single metal layer is commonly used, but its resolution is limited because of broad resonances. In this context, we have developed a sensor chip based on a stack of metals and a dielectric, e.g. a metal‐insulator‐metal structure, consisting of a thick insulator layer sandwiched by metal layers, that exhibits a sharp resonance due to the excitation of surface plasmon polaritons hybrid modes. We have performed both experiments and theoretical simulations to estimate the enhancement of the sensitivity of such a structure. By changing the refractive index of an aqueous solution of glucose on top of the sensor chip, we found that the use of a metal‐insulator‐metal structure improves the figure of merit of the sensor 7.5 times compared to that of a conventional surface plasmon resonance sensor chip.     

Plasmonic Airy beams with dynamically controlled trajectories

We report the experimental generation and dynamic trajectory control of plasmonic Airy beams (PABs). The PABs are created by directly coupling free-space Airy beams to surface plasmon polaritons through a grating coupler on a metal surface. We show that the ballistic motion of the PABs can be reconfigured in real time by either a computer addressed spatial light modulator or mechanical means.     

Fano resonance and magneto-optical Kerr rotaion in periodic Co/Ni complex plasmonic nanostructure

we report a pure rerromagneuc metallic magnetopiasmonic structure consisting or two-dimensional oraerea Ni nanodisks array on Co film.With a sufficient height of the nanodisks,a steep and asymmetric Fano resonance can be excited in this structure.We attribute the fascinating spectral lineshape to the strong coupling between the excitation of surface plasmon polaritons at the interface and the localized surface plasmon resonance of nanodisks.The conclusion is fully confirmed by spectrum measurements in nanostructures with different heights.Furthermore,the enhancement and sign of the magneto-optical Kerr rotation in this structure are significantly modified by the Fano resonance.