Surface plasmon hybridized dressed states.

Surface plasmon hybridization provides new perspectives for light manipulation at the nanoscale and related applications in nanophotonics. Multiple hybridization between metallic layers inside plasmonic nanocavities displays properties similar to atomic dressed states. In this Letter, we propose to numerically and analytically investigate the case of a multilayer structure composed of stacked metallic (M) and insulator (I) thin films.

Localization of plasmon modes in a 2D photonic nanostructure with a controlled disorder.

In this paper, we focus on the optical properties of disordered hole arrays etched in a gold thin film. The disorder is induced and controlled using hole displacements following a Gaussian distribution and starting from a periodic array. The nanostructures present a transition from ordered arrays to short-range ordered arrays and random arrays by increasing the disorder amount.

Single Gold Bipyramid Nanoparticle Orientation Measured by Plasmon-Resonant Scattering Polarimetry.

The 3D orientation of a single gold nanoparticle is probed experimentally by light scattering polarimetry. We choose high-quality gold bipyramids (AuBPs) that support around 700 nm a well-defined narrow longitudinal localized surface plasmonic resonance (LSPR) which can be considered as a linear radiating dipole. A specific spectroscopic dark-field technique was used to control the collection angles of the scattered light.

Coupling a single dipole to a long-range surface plasmon device.

Embedding a thin layer of a noble metal between two symmetric media results in the hybridization of the surface plasmons, leading to the existence of a long-range surface plasmon (LRSP). In this Letter, we investigate numerically the coupling of a single dipole, as a probe, to this LRSP. Different de-excitation channels are available such as free space radiation and plasmonic modes in different proportions.

From localized to delocalized plasmonic modes, first observation of superradiant scattering in disordered semi-continuous metal films.

Our study proposes a new way to observe and explain the presence of extended plasmonic modes in disordered semi-continuous metal films before the percolation threshold. Attenuated total reflection spectroscopy allows us to follow the transition of plasmon modes from localized to delocalized resonances, but also reveals unobserved collective plasmon modes. These bright modes with out-of-plane polarization are transverse collective plasmonic resonances.

Leakage interferences applied to surface plasmon analysis.

We report the experimental combination of leakage radiation microscopy with a Young slit experiment to address the spatial coherence properties of surface waves. We applied this method to measurements of surface plasmon polaritons (SPPs). The relationship between the spatial decay and interference contrast allows us to extract the degree of coherence.

Confined Tamm plasmon lasers.

We demonstrate that confined Tamm plasmon modes can be advantageously exploited for the realization of new kind of metal/semiconductor lasers. Laser emission is demonstrated for Tamm structures with various diameters of the metallic disks which provide the confinement. A reduction of the threshold with the size is observed.

FDTD simulations of localization and enhancements on fractal plasmonics nanostructures.

A parallelized 3D FDTD (Finite-Difference Time-Domain) solver has been used to study the near-field electromagnetic intensity upon plasmonics nanostructures. The studied structures are obtained from AFM (Atomic Force Microscopy) topography measured on real disordered gold layers deposited by thermal evaporation under ultra-high vacuum. The simulation results obtained with these 3D metallic nanostructures are in good agreement with previous experimental results: the localization of the electromagnetic intensity in subwavelength areas ("hot spots") is demonstrated; the spectral and polarization dependences of the position of these "hot spots" are also satisfactory; the enhancement factors obtained are realistic compared to the experimental ones.

Spatial coherence properties of surface plasmon investigated by Young's slit experiment.

In this Letter, we present an original method to extract the optical properties of surface plasmon polaritons (SPPs) on silver surfaces. A two Young's slit experiment combined with a leakage radiation microscope has been built. By correlating both imagery and coherence measurements on the same area, we are able to address the evolution of the SPP spatial coherence along its propagation.

Isotropic broadband absorption by a macroscopic self-organized plasmonic crystal.

We describe the plasmonic properties of a two-dimensional periodic metallic grating of macroscopic size obtained by gold deposition on a self-assembled silica opal. Structural characterization shows a transition from microscopic order to isotropy at macroscopic scale. Optical reflection spectra exhibit a dip of almost complete absorption due to coupling to surface-plasmon-polaritons (SPP).

Experimental Determination of the Fluorescence Quantum Yield of Semiconductor Nanocrystals.

Many studies have considered the luminescence of colloidal II-VI nanocrystals, both in solution at a collective scale and at an individual scale by confocal microscopy. The quantum yield is an important figure of merit for the optical quality of a fluorophore. We detail here a simple method to determine the quantum yield of nanocrystals in solution as a function of the absorption.

Ligand-induced anisotropy of the two-photon luminescence of spherical gold particles in solution unraveled at the single particle level.

Here we report on the visible luminescence properties of individual spherical gold particles in solution, obtained by two-photon excited fluorescence correlation spectroscopy and by an original dual Rayleigh-fluorescence method, correlating the Rayleigh scattering and the luminescence fluctuations of the same particle. The results demonstrate that the power needed to observe the two-photon excited visible luminescence depends on the illuminated particle and that the corresponding emission is anisotropic at low power. These observations combined with the evolution of the dynamics of the luminescence with respect to excitation power are interpreted by the presence of unique emissive surface states that are randomly switched off and on by the heat-induced movement of the molecular coating.