Search results for "PLASMON RESONANCE"
showing 10 items of 212 documents
Increasing Nanoparticles’ Refractive Index Sensitivity
2012
Since the plasmon resonance of nanoparticles depends on the refractive index of the immediate environment, these particles form the basis of many sensing schemes . The sensitivity of plasmon sensors for the detection of changes in the environment varies greatly and depends on the particle material and its morphology (size and shape). To further increase this sensitivity by chemical modifications was another goal of my work.
Surface plasmon polaritons on metal cylinders with dielectric core
2001
International audience; Metal-cladded dielectric cylinders with submicron diameters may serve to model coated tips used in nearfield scanning optical microscopy. The signal measured may be greatly influenced by resonance effects due to eigenmodes of the probe. Especially, using a photon scanning tunneling microscope setup, gold-coated tips have been found to detect a signal proportional to the magnetic field distributions [E. Devaux et al.. Phys. Rev. B 62, 10 504 (2000)]. This effect is attributed to cylindrical surface plasmons. We present here fully retarded calculations of the dispersion and field patterns of the nonradiative plasmon modes in cylindrical geometry. We study the effect of…
Analysis of the angular acceptance of surface plasmon Bragg mirrors
2007
International audience; We analyze an important aspect of the behavior of surface plasmon polariton (SPP) Bragg mirrors: the dependence of the angular acceptance for reflection on the incidence angle. By means of leakage radiation microscopy, both in direct and Fourier space, we observe that the angular acceptance diminishes for increasing incidence angles. This effect, which can considerably affect the design of devices based on these elements, is shown to be the consequence of the decrease of the bandgap width with increasing incidence angle. (c) 2007 Optical Society of America.
Dielectric-loaded plasmonic waveguide-ring resonators
2009
International audience; Using near-field microscopy, the performance of dielectric-loaded plasmonic waveguide-ring resonators (WRRs) operating at telecom wavelengths is investigated for various waveguide-ring separations. It is demonstrated that compact ( footprint similar to 150 mu m(2)) and efficient ( extinction ratio similar to 13 dB) WRR-based filters can be realized using UV-lithography. The WRR wavelength responses measured and calculated using the effective-index method are found in good agreement. (c) 2009 Optical Society of America
Bend- and splitting loss of dielectric-loaded surface plasmon-polariton waveguides.
2008
International audience; The design, fabrication, characterization, and modeling of basic building blocks of plasmonic circuitry based on dielectric- loaded surface polariton waveguides, such as bends, splitters, and Mach- Zehnder interferometers are presented. The plasmonic components are realized by depositing subwavelength dielectric ridges on a smooth gold film using mass-production- compatible UV-photolithography. The near-field characterization at telecommunication wavelengths shows the strong mode confinement and low radiation and bend losses. The performance of the devices is found in good agreement with results obtained by full vectorial three-dimensional finite element simulations.…
Discontinuity induced angular distribution of photon plasmon coupling
2011
Metal-dielectric transitions are important structures that can display a host of optical characteristics including excitation of plasmons. Metal-dielectric discontinuities can furthermore support plasmon excitation without a severe condition on the incident angle of the exciting photons. Using a semi-infinite thin gold film, we study surface plasmon (SP) excitation and the associated electromagnetic near-field distribution by recording the resulting plasmon interference patterns. In particular, we measure interference periods involving SPs at the scanable metal/air interface and the buried metal/glass one. Supported by optical near-field simulations and experiments, we demonstrate that the …
Rôle des antigènes tissulaires de groupes sanguins humains A, B, H et Lewis dans l'évolution des Norovirus GII.4
2011
Noroviruses are one of the leading causes of gastroenteritis worldwide. Since 2002 successive GII.4 variants have circulated in the population before being replaced every 2-3 years, which raises questions about the role of their histo-blood group antigen (HBGAs) receptors in their evolution. We analyzed the interaction between representative GII.4 variants and HBGAs and determined the role of selected amino acids (aa) in the binding profiles. By mutagenesis, we showed that there was a strict structural requirement for the aa directly implicated in HBGA bindings. The ablation of the threonine 395 residue, an epidemiological feature of the post 2002 variants, allowed to gain the capacity to b…
Surface plasmon interference excited by tightly focused laser beams
2007
International audience; We show that interfering surface plasmon polaritons can be excited with a focused laser beam at normal incidence to a plane metal film. No protrusions or holes are needed in this excitation scheme. Depending on the axial position of the focus, the intensity distribution on the metal surface is either dominated by interferences between counterpropagating plasmons or by a two-lobe pattern characteristic of localized surface plasmon excitation. Our experiments can be accurately explained by use of the angular spectrum representation and provide a simple means for locally exciting standing surface plasmon polaritons.
Acetone Vapor-Sensing Properties of Chitosan-Polyethylene Glycol Using Surface Plasmon Resonance Technique
2020
To non-invasively monitor and screen for diabetes in patients, there is need to detect low concentration of acetone vapor in the range from 1.8 ppm to 5 ppm, which is the concentration range of acetone vapor in diabetic patients. This work presents an investigation for the utilization of chitosan-polyethylene glycol (PEG)-based surface plasmon resonance (SPR) sensor in the detection of trace concentration acetone vapor in the range of breath acetone in diabetic subjects. The structure, morphology, and elemental composition of the chitosan-PEG sensing layer were characterized using FTIR, UV-VIS, FESEM, EDX, AFM, and XPS methods. Response testing was conducted using low concentration of aceto…
A metal-responsive interdigitated bilayer for selective quantification of mercury( ii ) traces by surface plasmon resonance
2016
Reusable surface plasmon resonance chips allowing the quantitative and selective detection of mercury(II) ions in water at the 0.01 nM level are reported. The surface-modified gold sensor consists of a rarefied self-assembled monolayer of octanethiol topped with a Langmuir–Blodgett monolayer of an amphiphilic and highly-specific chelator. The interdigitated architecture confers to the bilayer a high packing density, surface coverage, and binding-group accessibility.