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Plasmonics sensor configurations utilizing localized plasmon resonances in silver nanostructures typically suffer from rapid degradation of silver in ambient atmospheric conditions. In this work, we report on the fabrication and detailed characterization of ensembles of monocrystalline silver nanoparticles (NPs), which exhibit a long-term stability of optical properties under ambient conditions without any protective treatments. Ensembles with different densities (surface coverages) of size-selected NPs (diameters from 12.5 to 24 nm) on quartz substrates are fabricated using the cluster-beam technique and characterized by linear spectroscopy, surface-enhanced Raman scattering microscopy as well as transmission electron, helium-ion and atomic force microscopies. It is found that the fabricated ensembles of monocrystalline silver NPs preserve their plasmonic properties (monitored with optical spectroscopy) and strong field enhancements (revealed by surface enhanced Raman spectroscopy) at least 5 times longer as compared to chemically synthesized silver NPs with similar sizes. The obtained results are of high practical relevance for the further development of sensors, resonators and metamaterials utilizing plasmonic properties of silver NPs.

Power consumption and bandwidth of electronics appear as the main set of technology barriers in next-generation Data Center and High-Performance Computing (HPC) environments. The limited capacity and pitch lane of electrically wired interconnects require the development of new disruptive technologies to cope with the massive amount of data moving across all hierarchical communication levels, namely rack-to-rack, backplane, chip-to-chip and even on-chip interconnections. Plasmonics comes indeed as a disruptive technology that enables seamless interoperability between light beams and electronic control signals through the underlying metallic layer, providing thereby an inherent energy-efficient platform for merging broadband optical links with intelligent electronic processing. In ICT PLATON project we are aiming to the exploitation of plasmonics for the demonstration of novel hybrid Si-plasmonic router prototypes for chip-to-chip and on-chip interconnection, starting with a 2×2 WDM-traffic router with up to 640 Gb/s capacity and proceeding to a 4×4 router with up to 1.12 Tb/s throughput. In this article, we will present preliminary results of a 2×2 Si-plasmonic router that employs two 81 Si-ring-based multiplexers followed by a novel hybrid Si-plasmonic Mach Zehnder Interferometer switch with a record low power x time constant product. © 2013 IEEE. Power consumption and bandwidth of electronics appear as the main set of technology barriers in next-generation Data Center and High-Performance Computing (HPC) environments. The limited capacity and pitch lane of electrically wired interconnects require the development of new disruptive technologies to cope with the massive amount of data moving across all hierarchical communication levels, namely rack-to-rack, backplane, chip-to-chip and even on-chip interconnections. Plasmonics comes indeed as a disruptive technology that enables seamless interoperability between light beams and electronic control signals through the underlying metallic layer, providing thereby an inherent energy-efficient platform for merging broadband optical links with intelligent electronic processing. In ICT PLATON project we are aiming to the exploitation of plasmonics for the demonstration of novel hybrid Si-plasmonic router prototypes for chip-to-chip and on-chip interconnection, starting with a 2×2 WDM-traffic router with up to 640 Gb/s capacity and proceeding to a 4×4 router with up to 1.12 Tb/s throughput. In this article, we will present preliminary results of a 2×2 Si-plasmonic router that employs two 81 Si-ring-based multiplexers followed by a novel hybrid Si-plasmonic Mach Zehnder Interferometer switch with a record low power x time constant product.

Femtosecond laser-induced transfer, developed for the generation of metallic micro- and nanoparticles [1], is applied to the fabrication of Si nanoparticles. This method allows controllable fabrication of high quality spherical Si nanoparticles with radii of 50-300 nm. Measured light scattering spectra of individual Si nanoparticles demonstrate strong resonant responses in the visible and near-infrared spectral ranges. Theoretical analysis on the basis of Mie theory with a multipole decomposition shows that the first two low-frequency resonances correspond to the magnetic dipole and electric dipole modes. At these resonances, Si nanoparticles generate scattered waves as magnetic and electric dipoles, respectively. Due to high Si permittivity, the magnetic dipole resonance is observed in the visible spectral range for Si nanoparticles with diameters of 100-200 nm. Magnetic optical response of non-spherical Si nanoparticles is also studied using numerical simulations [2]. Possibilities for the realization of isotropic optical metamaterials on the basis of the Si nanoparticles with negative permeability or negative refraction index in the visible spectral range are discussed.

Field intensity enhancements (FEs) produced by gold needle nanostructures, namely, standing upright sharp and sphere-terminated needles, fabricated on a gold substrate by femtosecond laser irradiation, are investigated and characterized using linear reflection spectroscopy, two-photon photoluminescence (TPL) scanning optical microscopy, and high-resolution confocal Raman microscopy. Surface enhanced Raman scattering (SERS) is observed using linearly polarized 532 nm excitation of Rhodamine 6G homogeneously adsorbed on the structures. The obtained high-resolution TPL and Raman images both indicate a relatively high FE level of -75 for the fabricated structures. We believe that the observed FE levels along with the special topography make these upright elongated structures particularly promising for SERS experiments with living cells. © 2011 Optical Society of America.

The explosive progress in nanoscience has led to uncovering and exploring numerous physical phenomena occurring at nanoscale, especially when metal nanostructures are involved so that optical fields and electronic oscillations can be resonantly coupled. The latter is the subject of (nano) plasmonics with implications extending from subwavelength waveguiding to localized field enhancements. In this review paper, we consider making use of various phenomena related to multiple scattering of surface plasmons (SPs) at periodically and randomly (nano) structured metal surfaces. After reviewing the SP waveguiding along channels in nanostructured areas exhibiting band-gap and localization effects, SP-driven field enhancement in random structures and plasmonic fractal drums is discussed in detail. SP manipulation and waveguiding using periodic nanostructures on the long-wavelength side of the band gap is also considered. © 2009 by WILEY-VCH Verlag GmbH & Co.KGaA, Weinheim.

International audience; The excitation of surface plasmon-polariton (SPP) waveguide modes in 500-nm-wide and 550-nm-high dielectric ridges deposited on a thin gold film is characterized at telecommunication wavelengths, by application of a scanning near-field optical microscope (SNOM), and by utilizing the finite element method (FEM). Different tapering structures for coupling in SPPs, excited at the bare gold-air interface, are investigated with a SNOM, and the dependence of in coupling efficiency on tapering length is characterized by means of FEM calculations. The performance of this in coupling method is compared to an alternative excitation scheme, where the effective index of SPPs in the tapering region is matched to the index of the incident beam, thereby exciting SPPs directly in the dielectric tapering structure. Single-mode guiding and strong lateral mode confinement of dielectric-loaded SPP waveguide (DLSPPW) modes are demonstrated by characterizing a straight DLSPPW section with a SNOM and with the effective index method (EIM). The propagation loss of DLSPPW modes is characterized for different wavelengths in the telecommunication region, by application of a SNOM, and the results are compared to EIM calculations.

Three-dimensional focusing of evanescent waves by specially configured surface arrays of nanoparticles emulating near-field optical holograms of dipole sources (located close to the surface) is suggested and analyzed. The idea is to place chains of nanoparticles along bright fringes of calculated (holographic) interference patterns so that the local nanoparticle density along these chains would be proportional to the local intensity contrast in the interference patterns. Three different configurations are considered: a holographic scheme with totally internally reflected reference and reconstructing waves, a modified scheme with the reconstructing wave being represented by a suitable surface plasmon polariton (SPP) plane wave, and a SPP holographic scheme with reference and reconstructing waves both being (phase-conjugated) laterally-confined (Gaussian) SPP beams. Our numerical approach is based on the Green's function technique with the point-dipole approximation for radiation scattering by nanoparticles. We demonstrate that a nanoparticle array configured in accordance with the intensity interference pattern formed by a dipole field and a reference wave allows one to efficiently focus the (phase-conjugated) reconstructing wave (via its scattering by the nanoparticle array) at the site of the dipole. Influence of the polarization and wavelength of the reconstructing wave on the resulting intensity distribution is also considered. Fabrication of suitable nanoparticle arrays is discussed along with their potential applications. © 2008 Optical Society of America.