Search results for "Localized surface plasmon"

Efficient surface plasmon field confinement in one-dimensional crystal line-defect waveguides

2006

International audience; The authors operate a near-field optical microscope to investigate surface plasmon polariton (SPP) propagation along linear waveguides opened into one-dimensional (1D) plasmonic crystals, i.e., crystals featuring a single lattice plane orientation. They show that efficient SPP field confinement can be achieved by this type of waveguide although no band gap exists in the direction perpendicular to the waveguide axis. From computed wave-vector diagrams, they show that 1D plasmonic crystals can open a wide range of prohibited propagation directions preventing from a significant coupling of the waveguide SPP modes with the crystal Bloch modes. Finally, the authors demons…

Mie plasmon in polyhedral metal clusters

1995

We study the dependence of the classical plasmon frequency on the symmetry of the metal cluster and show that all clusters with at least two three-fold axes have the same plasmon frequency as the spherical cluster, ωp/√3. In these cases the effect of the geometry will only appear in the spill-out correction and in other quantum mechanical corrections.

Plasmon excitations in chemically heterogeneous nanoarrays

2020

| openaire: EC/H2020/838996/EU//RealNanoPlasmon The capability of collective excitations, such as localized surface plasmon resonances, to produce a versatile spectrum of optical phenomena is governed by the interactions within the collective and single-particle responses in the finite system. In many practical instances, plasmonic metallic nanoparticles and arrays are either topologically or chemically heterogeneous, which affects both the constituent transitions and their interactions. Here, the formation of collective excitations in weakly Cu- and Pd-doped Au nanoarrays is described using time-dependent density functional theory. The additional impurity-induced modes in the optical respo…

Near-field beam displacement at surface plasmon resonance

2011

International audience; A finite-size beam exciting a surface plasmon polariton (SPP) in a prism coupling configuration experiences an in-plane displacement that can be used for the characterization of plasmonic components by means of near-field optical microscopy. We first demonstrate experimentally the existence of this displacement by taking near-field images of finite-width metal strips. Next, the properties of this shift are analyzed in detail. We investigate the dynamic of the near-field shift for an incident Gaussian beam as a function of illumination conditions. For beams with a narrow spectrum, we propose a straightforward derivation showing that the displacement depends on the ave…

Absence of mutual polariton scattering for strongly coupled surface plasmon polaritons and dye molecules with a large Stokes shift

2013

The understanding and control of the dynamics of hybrid modes consisting of strongly coupled surface plasmon polaritons and molecular excitations of dye molecules is of great timely interest, as it allows one to tailor interactions between optical signals as needed for active all-optical devices. Here we utilize dye molecules with an especially large Stokes shift to demonstrate the absence of mutual scatterings among the strongly coupled hybrid modes. We employ a quantum mechanical three-level model and show that the hybrid modes decay via dephasing and internal relaxation of the molecules to a fluorescing state of the dye, which can be used as a measure for the decay. Our results provide e…

Light trapping by plasmonic nanoparticles

2020

Abstract Metallic nanoparticles sustaining localized surface plasmon resonances are of great interest for enhancing light trapping in thin film photovoltaics. In this chapter, we explore the correlation between the structural and optical properties of self-assembled silver nanostructures fabricated by a solid-state dewetting process on various substrates relevant for silicon photovoltaics and later integrated into plasmonic back reflectors. Our study allows us to optimize the performance of nanostructures by identifying the fabrication conditions in which desirable circular and uniformly spaced nanoparticles are obtained. Second, we introduce a novel optoelectronic spectroscopic method that…

Plasmonic nanostructures for light trapping in photovoltaic

Metallic nanoparticles (NPs), sustaining localized surface plasmon resonances, are currently of great interest for enhancing light trapping in thin film solar cells. To be directly applicable in the photovoltaic industry, the NPs fabrication needs to be simple, reliable, low-cost and scalable. As such, self-assembly processes are most commonly used, and Ag is the preferred material, due to its high radiative efficiency and low imaginary permittivity⁠. After exploring the correlation between structural and optical properties of Ag NPs fabricated by solid- state dewetting process on various substrates, we identified the fabrication conditions in which desirable NPs are obtained, but we also e…

Optimization of surface plasmons launching from subwavelength hole arrays: modelling and experiments

2009

International audience; The launching of surface plasmons by micro-gratings of subwavelength apertures milled in a thick metal film is important for the development of surface plasmon based circuits. By comparing the near-field optical images of such surface plasmon sources with the results of a Huygens-Fresnel principle based scattering model, we show that the properties of the locally launched SP beams such as divergence or uniformity can be tuned by adjusting the shape of the micro-gratings. This allows us to propose an optimized source array well adapted for providing a narrow, collimated and uniform beam. (c) 2007 Optical Society of America.

Imaging of surface plasmon propagation and edge interaction using a photon scanning tunneling microscope

1994

We report the direct imaging of surface plasmon propagation on thin silver films using the photon scanning tunneling microscope. It is found that the surface plasmon remains tightly confined in the original launch direction with insignificant scattering to other momentum states. A propagation length of 13.2 \ensuremath{\mu}m is measured at \ensuremath{\lambda}=632.8 nm. We also present images showing the interaction of a surface plasmon with the edge of the metal film supporting it. The most remarkable feature is the absence of specularly reflected beam.

Quantifying the trade-off between useful and parasitic absorption of light for plasmonic light trapping in thin silicon films

2016

We apply a combination of photocurrent and photothermal spectroscopic techniques to experimentally quantify the trade-off between useful and parasitic absorption of light in thin hydrogenated microcrystalline silicon (?c-Si:H) films incorporating self-assembled silver nanoparticle arrays, located at the rear side, for improved light trapping via resonant plasmonic scattering. The photothermal technique is used to measure the total absorptance while the photocurrent spectroscopy accounts only for the photons absorbed in the ?c-Si:H layer (useful absorptance); therefore, the method allows for independent quantification of the useful and parasitic absorptance of the plasmonic (or any other) li…