Leaky radiation microscopy (LRM) is used to directly image the surface plasmon-coupled emission (SPCE). When compared with the prism based set-up commonly used in SPCE research, LRM has the advantages of directly giving out the emitting angle without scanning and the image of generated surface plasmons polaritons (SPPs) propagation, which help to understand the optical process of SPCE. LRM also can give out clearer SPCE image than that by prism-based set-up. Based on the LRM, we find that the SPCE pattern and propagation of SPPs can be modified by the shape of samples fabricated on the thin metallic films.
Stimulated Raman scattering (SRS) microscopy allows for high-speed label-free chemical imaging of biomedical systems. The imaging sensitivity of SRS microscopy is limited to ~10 mM for endogenous biomolecules. Electronic pre-resonant SRS allows detection of sub-micromolar chromophores. However, label-free SRS detection of single biomolecules having extremely small Raman cross-sections (~10-30 cm2 sr-1) remains unreachable. Here, we demonstrate plasmon-enhanced stimulated Raman scattering (PESRS) microscopy with single-molecule detection sensitivity. Incorporating pico-Joule laser excitation, b…
Polaritons are compositional light-matter quasiparticles that have recently enabled remarkable breakthroughs in quantum and nonlinear optics, as well as in material science. Despite the enormous progress, however, a direct nanometer-scale visualization of polaritons has remained an open challenge. Here, we demonstrate that plasmon-exciton polaritons, or plexcitons, generated by a hybrid system composed of an individual silver nanoparticle and a few-layer transition metal dichalcogenide can be spectroscopically mapped with nanometer spatial resolution using electron energy loss spectroscopy in …
Dispersion features of a graphene-coated semiconductor nanowire operating in the terahertz frequency band are consistently studied in the framework of a special theory of complex waves. Detailed classification of the waveguide modes was carried out based on the analysis of characteristics of the phase and attenuation constants obtained from the complex roots of characteristic equation. With such a treatment, the waves are attributed to the group of either 'proper' or 'improper' waves, wherein their type is determined as the trapped surface waves, fast and slow leaky waves, and surface plasmons…
Evanescently coupled waveguides are a powerful platform to study and visualize the wave dynamics in tight-binding systems. Here, we investigate the propagation of surface plasmon polaritons in arrays of dielectric loaded surface plasmon polariton waveguides with a propagation constant gradient acting as an effective external potential. Using leakage radiation microscopy, we observe in real-space for single site excitation a periodic breathing of the wavepacket and an oscillatory motion in the case of Gaussian excitation of multiple waveguides. The corresponding momentum resolved spectra are co…
The determination of the chemical content is crucial for the quality control in high-precision device fabrication and advanced process development. For reliable chemical composition characterization, certain interaction volume of the target material is necessary for conventional techniques such as energy-dispersive X-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS). This remains however a challenge for nanostructures. We hereby propose an alternative technique for measuring chemical composition of nanostructures with limited volume. By measuring the differences in the optica…
We report on the first experimental demonstration that the microstructure based on a dielectric cuboid combined to a thin metal film can act as an efficient plasmonic lens allowing focusing surface plasmons in a subwavelength scale. By means of numerical simulation of surface plasmon-polariton (SPP) field intensity distributions in the microstructure, we observe a low divergence of plasmonic photonic jet (PPJ) and high intensity subwavelength spots at the communication wavelength of 1530 nm. Then we fabricate an experimental sample of the microstructure and study the SSP field intensity distri…
The tailoring of plasmonic near-fields is central to the field of nanophotonics. The detailed knowledge of the field distribution is crucial for a design and fabrication of plasmonic sensors, detectors, photovoltaics, plasmon-based cicuits, nanomanipulators, electrooptic plasmonic modulators and atomic devices. We report on a fully quantitative comparison between near field observation and numerical calculations, considering the intensity distribution for TM and TE polarisations, necessary for the construction of devices in all these areas. We present the near field scanning microscopy (NSOM) …
A recent study shows that: when a long lifetime particle is positioned near a plasmonic metal nanoparticle, lifetime of plasmon oscillations extends, but, "only" near that long-life particle [PRB 101, 035416 (2020)]. Here, we show that this phenomenon can be utilized for ultrahigh (single-molecule) resolution ultrafast apertureless (scattering) SNOM applications. We use the exact solutions of 3D Maxwell equations. We illuminate a metal-coated silicon tip, a quantum emitter (QE) placed on the tip apex, with a femtosecond laser. The induced near-field in the apex decays rapidly except in the vic…
Correlated polarization dependences between surface-enhanced resonant Raman scattering and plasmon resonance elastic scattering showing spectral uncorrelation to each other
Real-time surface plasmon polariton propagation in silver nanowires
Max-Born-Institut（马克斯·伯恩研究所）；Humboldt-Universität zu Berlin（柏林洪堡大学）；Center for the Science of Materials Berlin, Humboldt-Universität zu Berlin（柏林材料科学中心，柏林洪堡大学）；Helmholtz-Zentrum Berlin for Materials and Energy（柏林亥姆霍兹材料与能源中心）；Friedrich-Schiller-University（弗里德里希·席勒大学）
Understanding the differences between photon-induced and plasmon-induced hot electrons is essential for the construction of devices for plasmonic energy conversion. The mechanism of the plasmonic enhancement in photochemistry, photocatalysis, and light-harvesting and especially the role of hot carriers is still heavily discussed. The question remains, if plasmon-induced and photon-induced hot carriers are fundamentally different, or if plasmonic enhancement is only an effect of field concentration producing these carriers in greater numbers. For the bulk plasmon resonance, a fundamental differ…
We report thorough measurements of surface plasmon polaritons (SPPs) running along nearly perfect air-gold interfaces formed by atomically flat surfaces of chemically synthesized gold monocrystals. By means of amplitude- and phase-resolved near-field microscopy, we obtain their propagation length and effective mode index at visible wavelengths (532, 594, 632.8, 729, and 800 nm). The measured values are compared with the values obtained from the dielectric functions of gold that are reported in literature. Importantly, a reported dielectric function of monocrystalline gold implies $\sim 1.5$ ti…
Physical mechanisms of electron emission from fibre optic nanotips, namely, tunnelling, multi-photon, and thermionic emission, either prevent fast switching or require intense laser fields. Time-resolved electron emission from nano-sized sources finds applications ranging from material characterisation to fundamental studies of quantum coherence. We present a nano-sized electron source capable of fast-switching (<1 ns) that can be driven with low-power femtosecond lasers. The physical mechanism that can explain emission at low laser power is surface plasmon enhanced above-threshold photoemissi…
Herein, we report sub-wavelength propagation and directional out-coupling of whispering gallery modes (WGMs) of a fluorescent silica microsphere resonator mediated via plasmon polaritons in a single crystalline silver nanowire. Fluorescent spectral signatures of emission from the nanowire ends confirm efficient guiding of WGMs via nanowire plasmons. By employing Fourier plane optical microscopy, we reveal and quantify the directional fluorescence emission of WGMs from the ends of the nanowire. Given that the discussed geometry is self-assembled from a solution-phase, our results will find rele…
Scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS) has become a standard technique to map localized surface plasmon resonances with a nanometer spatial and a sufficient energy resolution over the last 15 years. However, no experimental work discussing the influence of experimental conditions during the measurement has been published up to now. We present an experimental study of the influence of the primary beam energy and the collection semi-angle on the plasmon resonances measurement by STEM-EELS. To explore the influence of these two expe…
Photoexcitation and shaping of a propagating surface plasmon polariton (SPP) on silver and gold microstructures are well established and lead to the discovery of the plasmonic spin-Hall effect recently. Whereas silver is often the material of choice due to its exceptional low plasma frequency and weak damping, similar observations have not been reported for ferromagnetic metals. In this work, we report on propagating SPPs on Ni$_{80}$Fe$_{20}$ microstructures imaged by photoemission electron microscopy (PEEM) in combination with a tunable femtosecond laser system at MHz repetition rate. Circul…
Influencing spectral and directional features of exciton emission characteristics from 2D transition metal dichalcogenides by coupling it to plasmonic nano-cavities has emerged as an important prospect in nanophotonics of 2D materials. In this paper we experimentally study the directional photoluminescence emission from Tungsten disulfide (WS2) monolayer sandwiched between a single-crystalline plasmonic silver nanowire (AgNW) waveguide and a gold (Au) mirror, thus forming an AgNW-WS2-Au cavity. By employing polarization-resolved Fourier plane optical microscopy, we quantify the directional emi…
Diffraction of light at lateral inhomogenities is a central process in the near-field studies of nanoscale phenomena, especially the propagation of surface waves. Theoretical description of this process is extremely challenging due to breakdown of plane-wave methods. Here, we present and analyze an exact solution for electromagnetic wave diffraction at the linear junction between two-dimensional electron systems (2DES) with dissimilar surface conductivities. The field at the junction is a combination of three components with different spatial structure: free-field component, non-resonant edge …
Vertical nanowires facilitate an innovative mechanism to channel the optical field in the orthogonal direction and act as a nanoscale light source. Subwavelength, vertically oriented nanowire platforms, both of plasmonic and semiconducting variety can facilitate interesting far field emission profiles and potentially carry orbital angular momentum states. Motivated by these prospects, in this letter, we show how a hybrid plasmonic - organic platform can be harnessed to engineer far field radiation. The system that we have employed is an organic nanowire made of diaminoanthroquinone grown on a …
