News

  • Thumbnail

    A lunch with an astronaut

    today - Swiss Space Center Three students had the opportunity to meet Claude Nicollier after they won a competition organized by the Swiss Space Center at the TecDay in Zofingen in February.

  • Thumbnail

    EPFL IEEE student wins the IEEE Region 8 Student Paper Contest 2014

    today - IEEE Student Branch Slobodan Mitrović won the first prize of the contest with his paper "Homometric Sets in Diameter-two and Outerplanar Graphs". Slobodan's paper was selected to be one of the five finalist papers, and he managed to get the first position after the presentation of his work during the MELECON 2014 Conference, which took place last Tuesday (15.04.2014) in Beirut, Lebanon.

  • Thumbnail

    High level visit and inauguration of swissnex Brazil

    yesterday - Cooperation BRAZIL: April 4-6, 2014 EPFL participates with the official Visit of FC Johann N. Schneider-Ammann in Brazil

  • Thumbnail

    Detection limit of plasmonic antennas

    yesterday - Nanophotonics and Metrology We use numerical simulations based on the surface integral technique to study the detection limit of plasmonic trapping with realistic dipole antennas. The induced plasmon resonance shift due to the coupling between an antenna and a nanoparticle is studied for different antennas geometries, different positions, sizes, and materials for the trapped nanoparticle. The shift of the antenna resonance is found to be linear with the near-field intensity enhancement caused by the antenna and further dependents on the volume and refractive index of the trapped nanoparticle. Detection limit of 5 nm for plasmonic particles and 6.5 nm for high index dielectrics is reported.

  • Thumbnail

    Bending plasmons around the corner

    yesterday - Nanophotonics and Metrology Using a finite-element, full-wave modeling approach, we present a flexible method of analyzing and simulating dielectric and plasmonic waveguide structures as well as their mode coupling. This method is applied to an integrated plasmonic circuit where a straight dielectric waveguide couples through a straight hybrid long-range plasmon waveguide to a uniformly bent hybrid one. The hybrid waveguide comprises a thin metal core embedded in a two–dimensional dielectric waveguide. The performance of such plasmonic circuits in terms of insertion losses is discussed.

  • Thumbnail

    Oxygen sensing using a strongly coupled bio-plasmonic system

    yesterday - Nanophotonics and Metrology We investigate theoretically the strong coupling between surface plasmon resonances (SPRs) and absorption bands of hemoglobin. When the surface plasmon resonance spectrally overlaps the absorption bands of hemoglobin, the system is strongly coupled and its dispersion diagram exhibits an anti-crossing. Working in the conditions of strong coupling enhances the sensitivity of a SPR sensor up to a factor of 10. A model for the permittivity of hemoglobin, both in oxygenated and deoxygenated states, is presented and the study is carried out for both angle and wavelength modulated SPR sensors. Finally, a differential measurement is shown to increase the sensitivity further.

  • Thumbnail

    Ab initio theory of Fano resonances in plasmonic systems

    yesterday - Nanophotonics and Metrology The transition from localized to delocalized plasmons (i.e. the transition from a situation where the decay length of a travelling surface plasma wave is greater than its propagation distance to a situation where it is smaller) and hence the onset of plasmon delocalization is studied in a single 2D silver nanoparticle of increasing length. A fourier analysis in the near-field of the nanoparticle is used as the main tool for analysis. This method, along with far-field scattering spectra simulations and the near-field profile directly above and along the length of the nanoparticle are used to investigate and clearly show the transition from localized to delocalized modes. In particular, it is found that for a finite sized rectangular nanoparticle, both the emerging odd and even delocalized modes are nothing but a superposition of many standing wave plasmon modes. As a consequence, even very short metal films can support delocalized plasmons that bounce back and forth along the film.

  • Thumbnail

    When do plasmons start to propagate?

    yesterday - Nanophotonics and Metrology The transition from localized to delocalized plasmons (i.e. the transition from a situation where the decay length of a travelling surface plasma wave is greater than its propagation distance to a situation where it is smaller) and hence the onset of plasmon delocalization is studied in a single 2D silver nanoparticle of increasing length. A fourier analysis in the near-field of the nanoparticle is used as the main tool for analysis. This method, along with far-field scattering spectra simulations and the near-field profile directly above and along the length of the nanoparticle are used to investigate and clearly show the transition from localized to delocalized modes. In particular, it is found that for a finite sized rectangular nanoparticle, both the emerging odd and even delocalized modes are nothing but a superposition of many standing wave plasmon modes. As a consequence, even very short metal films can support delocalized plasmons that bounce back and forth along the film.

  • Thumbnail

    SERS on Silver-coated Carbon nanotubes

    yesterday - Nanophotonics and Metrology The electric field enhancement associated with detailed structure within novel optical antenna nanostructures is modeled using the surface integral equation technique in the context of surface-enhanced Raman scattering (SERS). The antennae comprise random arrays of vertically aligned, multiwalled carbon nanotubes dressed with highly granular Ag. Different types of “hot-spot” underpinning the SERS are identified, but contrasting characteristics are revealed. Those at the outer edges of the Ag grains are antenna driven with field enhancement amplified in antenna antinodes while intergrain hotspots are largely independent of antenna activity. Hot-spots between the tops of antennae leaning towards each other also appear to benefit from antenna amplification.

  • Thumbnail

    Modelling realistic plasmonic nanoparticles

    yesterday - Nanophotonics and Metrology The enhancement of excitation and reemission of molecules in close proximity to plasmonic nanostructures is studied with special focus on the comparison between idealized and realistically shaped nanostructures. Numerical experiments show that for certain applications choosing a realistic geometry closely resembling the actual nanostructure is imperative, an idealized simulation geometry yielding significantly different results. Finally, a link between excitation and reemission processes is formed via the theory of optical reciprocity, allowing a transparent view of the electromagnetic processes involved in plasmon-enhanced fluorescence and Raman-scattering.

Search news

Filter by date

Filter by theme

Filter by faculty

Filter by public

Filter by category