Light-matter interactions mediated by nanoscale confinement in plasmonic resonators

Plasmonic resonators are nanosized metallic antennas that convert electromagnetic waves at optical frequencies into localized fields, providing an effective route to couple photons in and out of nanoscale volumes. This unique ability makes these nanostructures excellent tools to study and manipulate light-matter interaction at the nanoscale. The strong coupling of a plasmonic resonator to light, resulting in optical cross-sections of more than 10 times the particle’s physical size, is driven by collective oscillations of the conduction electrons in the metal – the so-called surface plasmon resonances. In the first part of this presentation, we will discuss how plasmonic resonances influence the second harmonic generation (SHG) from different resonator geometries. Linear optical properties examined by reflection spectroscopy, aperture scanning near-field optical microscopy (aperture-SNOM), and finite difference time domain (FDTD) simulations reveal the supported plasmonic modes and their field and current distributions [1,2]. These results are then compared with SHG microscopy measurements [3-5]. Luminescent Ag nanoclusters have been extensively studied recently for a variety of applications, such as bio-nanolabels, UV-driven white light generation for luminescent lamps, flexible screen monitors, and down-conversion of solar spectrum for enhanced solar cells. Bulk oxyfluoride glasses can embed such small Ag nanoclusters [6]. However, an extra heat treatment below the glass transition temperature of these glasses results in condensation of the Ag nanoclusters into Ag nanoparticles larger than 1 nm. In the second part of the talk, we will discuss how the surface plasmon modes in these nanoparticles mediate the luminescence of the Ag doped oxyfluoride glass [7].status: publishe

Volumetric method of moments and conceptual multilevel building blocks for nanotopologies

Based on the relationship between charge dimensionality and singular field behavior, it is proven that in a volumetric description of a volume current carrying topology, half rooftops of different binary hierarchical level are allowed without introducing numerical difficulties. This opens the possibility to use a very efficient multi-level hierarchical meshing scheme in a Volumetric Method of Moments (MoM) algorithm. The new meshing scheme is validated by numerical calculations and experiments. It paves the way towards a much more efficient use of MoM in the description of arbitrarily shaped nano-structures at IR and optical frequencies

Plasmon-enhanced sub-wavelength laser ablation: plasmonic nanojets

In response to the incident light's electric field, the electron density oscillates in the plasmonic hotspots producing an electric current. Associated Ohmic losses raise the temperature of the material within the plasmonic hotspot above the melting point. A nanojet and nanosphere ejection can then be observed precisely from the plasmonic hotspots.status: publishe