In-plane remote photoluminescence excitation of carbon nanotube by propagating surface plasmon
International audience; In this work, we demonstrate propagating surface plasmon polariton (SPP) coupled photoluminescence (PL) excitation of single-walled carbon nanotube (SWNT). SPPs were launched at a few micrometers from individually marked SWNT, and plasmon-coupled PL was recorded to determine the efficiency of this remote in-plane addressing scheme. The efficiency depends upon the following factors: (i) longitudinal and transverse distances between the SPP launching site and the location of the SWNT and (ii) orientation of the SWNT with respect to the plasmon propagation wave vector (k(SPP)). Our experiment explores the possible integration of carbon nanotubes as a plasmon sensor in p…
Scanning optical microscopy modeling in nanoplasmonics
International audience; One of the main purposes of nanoplasmonics is the miniaturization of optical and electro-optical components that could be integrable in coplanar geometry. In this context, we propose a numerical model of a polarized scanning optical microscope able to faithfully reproduce both photon luminescence and temperature distribution images associated with complex plasmonic structures. The images are computed, pixel by pixel, through a complete self-consistent scheme based on the Green dyadic functions (GDF) formalism. The basic principle consists in the numerical implementation of a realistic three-dimensional light beam acting as a virtual light tip able to probe the volume…
The Single Molecule Probe: Nanoscale Vectorial Mapping of Photonic Mode Density in a Metal Nanocavity
International audience; We use superresolution single-molecule polarization and lifetime imaging to probe the local density of states (LDOS) in a metal nanocavity. Determination of the orientation of the molecular transition dipole allows us to retrieve the different LDOS behavior for parallel and perpendicular orientations with respect to the metal interfaces. For the perpendicular orientation, a strong lifetime reduction is observed for distances up to 150 nm from the cavity edge due to coupling to surface plasmon polariton modes in the metal. Contrarily, for the parallel orientation we observe lifetime variations resulting from coupling to characteristic λ/2 cavity modes. Our results are…
Dihedron dielectric loaded surface plasmon athermal polarization converter.
We investigate numerically a novel plasmonic polarization converter relying on the excitation of a so-called dihedron dielectric loaded plasmon polariton. The dihedron dielectric loaded waveguide consists of a dielectric ridge implemented at the inner corner of a metal-coated dielectric step. For a dielectric ridge with a square cross section, the plasmon polariton modes supported by each side of the metallized step hybridize to create supermodes with crossed polarizations. We show that the two supermodes can be operated in a dual-mode interferometer configuration to perform an efficient (24 dB) TE-TM/TM-TE polarization conversion over typical distances below 30 μm at telecommunications wav…
Integrated plasmonic waveguides: A mode solver based on density of states formulation
International audience; We express the density of states (DOS) near guided resonances of plasmonic waveguides by using multiple-scattering theory. In direct analogy with the case of localized electronic defect states in condensed matter, we demonstrate that optical DOS variations follow a lorentzian profile near guided modes resonances. The lorentzian shape gives quantitative information on the guided modes (effective index, propagation length, and polarization state). We numerically investigate both leaky and bound (lossy) modes supported by dielectric-loaded surface-plasmon-polariton waveguides.
Momentum-space spectroscopy for advanced analysis of dielectric-loaded surface plasmon polariton coupled and bent waveguides
We perform advanced radiation leakage microscopy of routing dielectric-loaded plasmonic waveguiding structures. By direct plane imaging and momentum-space spectroscopy, we analyze the energy transfer between coupled waveguides as a function of gap distance and reveal the momentum distribution of curved geometries. Specifically, we observed a clear degeneracy lift of the effective indices for strongly interacting waveguides in agreement with coupled-mode theory. We use momentum-space representations to discuss the effect of curvature on dielectric-loaded waveguides. The experimental images are successfully reproduced by a numerical and an analytical model of the mode propagating in a curved …
Launching propagating surface plasmon polaritons by a single carbon nanotube dipolar emitter.
International audience; We report on the excitation of propagating surface plasmon polaritons in thin metal films by a single emitter. Upon excitation in the visible regime, individual semiconducting single-walled carbon nanotubes are shown to act as directional near-infrared point dipole sources launching propagating surface plasmons mainly along the direction of the nanotube axis. Plasmon excitation and propagation is monitored in Fourier and real space by leakage radiation microscopy and is modeled by rigorous theoretical calculations. Coupling to plasmons almost completely reshapes the emission of nanotubes both spatially and with respect to polarization as compared to photoluminescence…
Molecule non-radiative coupling to a metallic nanosphere: an optical theorem treatment.
The non-radiative coupling of a molecule to a metallic spherical particle is approximated by a sum involving particle quasistatic polarizabilities. We demonstrate that energy transfer from molecule to particle satisfies the optical theorem if size effects corrections are properly introduced into the quasistatic polarizabilities. We hope that this simplified model gives valuable information on the coupling mechanism between molecule and metallic nanos-tructures available for, e.g., surface enhanced spectroscopy signal analysis.
Colloidal Quantum Dot Integrated Light Sources for Plasmon Mediated Photonic Waveguide Excitation
We operate micron-sized CdSe/CdS core–shell quantum dot (QD) clusters deposited onto gold patches as integrated light sources for the excitation of photonic waveguides. The surface plasmon mode launched by the QD fluorescence at the top interface of the gold patches are efficiently coupled to photonic modes sustained by titanium dioxide ridge waveguides. We show that, despite a large effective index difference, the plasmonic and the photonic modes can couple with a very high efficiency provided the vertical offset between the two kinds of waveguides is carefully controlled. Based on the effective index contrast of the plasmonic and the photonic modes, we engineer in-plane integrated hybrid …
Influence of an Electron Beam Exposure on the Surface Plasmon Resonance of Gold Nanoparticles
Electron beam imaging is a common technique used for characterizing the morphology of plasmonic nanostructures. During the imaging process, the electron beam interacts with traces of organic material in the chamber and produces a well-know layer of amorphous carbon over the specimen under investigation. In this paper, we investigate the effect of this carbon adsorbate on the spectral position of the surface plasmon in individual gold nanoparticles as a function of electron exposure dose. We find an optimum dose for which the plasmonic response of the nanoparticle is not affected by the imaging process. The final publication is available at link.springer.com
Influence of the Number of Nanoparticles on the Enhancement Properties of Surface-Enhanced Raman Scattering Active Area: Sensitivity versus Repeatability
In the present work, the combination of chemical immobilization with electron beam lithography enables the production of sensitive and reproducible SERS-active areas composed of stochastic arrangements of gold nanoparticles. The number of nanoparticles was varied from 2 to 500. Thereby a systematic analysis of these SERS-active areas allows us to study SERS efficiency as a function of the number of nanoparticles. We found that the experimental parameters are critical, in particular the size of the SERS-active area must be comparable to the effective area of excitation to obtained reproducible SERS measurements. The sensitivity has also been studied by deducing the number of NPs that generat…
Near-field beam displacement at surface plasmon resonance
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…
Thermo-electric detection of waveguided surface plasmon propagation
International audience; The thermo-electric detection of a waveguided surface plasmon traveling along one electrode of an in-plane integrated thermocouple is demonstrated. By using a particular design of the thermocouple, the thermo-electric signal due to the losses of the plasmon mode can be separated from the non-resonant heating of the waveguide. The thermo-electric signal associated with the plasmon propagation is proportional to the power coupled into the waveguided mode and exhibits a maximum at a distance from the excitation site depending on both the heat transfer coefficient of the system and the plasmon mode damping distance.
Tuning of an Optical Dimer Nanoantenna by Electrically Controlling Its Load Impedance
International audience; Optical antennas are elementary units used to direct optical radiation to the nanoscale. Here we demonstrate an active control over individual antenna performances by an external electrical trigger. We find that by an in-plane command of an anisotropic load medium, the electromagnetic interaction between individual elements constituting an optical antenna can be controlled, resulting in a strong polarization and tuning response. An active command of the antenna is a prerequisite for directing light wave through the utilization of such a device.
Spontaneous hot-electron light emission from electron-fed optical antennas
Nanoscale electronics and photonics are among the most promising research areas providing functional nano-components for data transfer and signal processing. By adopting metal-based optical antennas as a disruptive technological vehicle, we demonstrate that these two device-generating technologies can be interfaced to create an electronically-driven self-emitting unit. This nanoscale plasmonic transmitter operates by injecting electrons in a contacted tunneling antenna feedgap. Under certain operating conditions, we show that the antenna enters a highly nonlinear regime in which the energy of the emitted photons exceeds the quantum limit imposed by the applied bias. We propose a model based…
Wave-vector analysis of plasmon-assisted distributed nonlinear photoluminescence along Au nanowires
We report a quantitative analysis of the wavevector diagram emitted by nonlinear photoluminescence generated by a tightly focused pulsed laser beam and distributed along Au nanowire via the mediation of surface plasmon polaritions. The nonlinear photoluminescence is locally excited at key locations along the nanowire in order to understand the different contributions constituting the emission pattern measured in a conjugate Fourier plane of the microscope. Polarization-resolved measurements reveal that the nanowire preferentially emits nonlinear photoluminescence polarized transverse to the long axis at close to the detection limit wavevectors with a small azimuthal spread in comparison to …
Imaging Symmetry-Selected Corner Plasmon Modes in Penta-Twinned Crystalline Ag Nanowires
International audience; Using dual-plane leakage radiation microscopy, we investigate plasmon propagation in individual penta-twinned crystalline silver nanowires. By measuring the wavevector content of the light emitted in the substrate, we unambiguously determine the effective index and the losses of the mode propagating in these structures. The experimental results, in particular, the unexpectedly low effective index, reveal the direct influence of the nanowire crystallinity and pentagonal structure on the observed plasmon modes. By analogy with molecular orbitals of similar symmetry, the plasmon modes are also determined numerically in good agreement with the observed values. We further…