Search results for "near-field"
showing 10 items of 101 documents
A near-field actuated optical nanocavity
2008
International audience; We demonstrate here that switching and tuning of a nanocavity resonance can be achieved by approaching a sub-micrometer tip inside its evanescent near-field. The resonance energy is tuned over a wide spectral range (Δλ/λ~10-3) without significant deterioration of the cavity peak-transmittance and of the resonance linewidth. Such a result is achieved by taking benefits from a weak tip-cavity interaction regime in which the tip behaves as a pure optical path length modulator.
Local detection of the optical magnetic field in the near zone of dielectric samples
2000
International audience; We present a study of the influence of the probe composition on the formation of constant-height photon scanning tunneling microscope images when observing a dielectric sample. Dramatic effects due to the metallization of the tip are presented and discussed in detail. We show how the recorded images can look quite different when the probe is dielectric or coated with gold. Comparison with numerical calculations indicate that the experimental signals are of electric or magnetic nature depending on the composition of the tip. For well-defined conditions, gold-coated tips provide images of the distribution of the magnetic field intensity associated with the optical near…
Excitation and characterization of dielectric-loaded surface plasmon-polariton waveguides at telecommunication wavelengths - art. no. 69880T
2008
International audience; The excitation of surface plasmon-polariton (SPP) waveguide modes in 500-nm-wide and 550-nm-high dielectric ridges deposited on a thin gold film is characterized at telecommunication wavelengths, by application of a scanning near-field optical microscope (SNOM), and by utilizing the finite element method (FEM). Different tapering structures for coupling in SPPs, excited at the bare gold-air interface, are investigated with a SNOM, and the dependence of in coupling efficiency on tapering length is characterized by means of FEM calculations. The performance of this in coupling method is compared to an alternative excitation scheme, where the effective index of SPPs in …
Étude et manipulation de modes résonants en champ proche optique
2010
Within the quick nano-fabrication techniques evolution and the increasing needs in low space and energy opto-electronic functions on-chip integration, studies and control of electromagnetic resonances of sub-micrometric objects are crucial issues. One aim of this work was then to improve our knowledge of the light-matter interaction. To this end, optical near-field experiments and complementary numerical development of models have been performed to study electromagnetic resonances due to light-matter interaction in sub-micrometric resonators. As an introduction, the first part of the manuscript presents the main phenomena involved in near-field optical microscopy and the used SNOM operation…
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 …
Hyperspectral near-field imaging : development and applications to nanophotonics devices
2013
The scanning near-field optical microscopy (SNOM) is used to analyze optical phenomena at the sub-wavelength scale such as light localization and propagation in photonic crystals or plasmonic devices. In any case, SNOM experiments rely on the positioning of a local probe in the optical near field of a given structure and on the detection of the surrounding evanescent waves. Depending on the nature of the probe or on the optical detection method, the detected physical properties are the spatial distributions of the amplitude and phase or the intensity of the electric and magnetic components of the probed field. We present here the implementation of an innovative hyperspectral near-field imag…
Spectroscopic Investigations Of LB Mono- And Multilayers Of 2-docosylamino 5-nitropyridine; Promising Candidates For Non-linear And Integrated Optics
2005
Alkylamino-5-nitropyridineshavemently been introduced forthepreparation of a novel type of non-centrosymmetric Langmuir-Blodgett (LB) multilayer (1,2). Hitherto, second order non-linear optical investigations have been resmcted toLB-films oftwomaterialsinaltematinglayerstructureand to films of a single material with head to tail arrangement of the molecules, both of whicharedifficulttoobtain (seerefs. quotedin 1 and2.1. Incontrast,allpresent data indicate that LB-filmsof 2-aUcylamino-5-nitropyridines are head-to-head and tail-to-tail (Y-type) multilayers with a rather strong tilt-angle of the alkyl chains (Fig. I). The most effective substance for second order non-linear optical experiments…
Polymers films with indandione derivatives as alternatives to azobenzene polymers for optical patterning
2008
Surface relief gratings (SRGs) on organic thin films are studied extensively for both scientific interest and in relevance to the applications. Among the chromophores being used the azobenzenes showed the best performance, but the use of alternative photo-sensitive groups provides better general understanding of the phenomena. A thermodynamic theory and molecular dynamics simulations of photoinduced effects are discussed. In this study we use indandione derivatives, known as promising materials for photonics applications, as an alternative to the azobenzenes. We consider their photoreactions when incorporated into a polymer film. One of interesting features is the spectral dependence of the…
Nanoscale probing of the supramolecular assembly in a two‐component gel by near‐field infrared spectroscopy
2023
The design of soft biomaterials requires a deep understanding of molecular self-assembly. We introduce here a nanoscale infrared (IR) spectroscopy study of a two-component supramolecular gel to assess the system´s heterogeneity and supramolecular assembly. In contrast to far-field IR spectroscopy, near-field IR spectroscopy revealed differences in the secondary structures of the gelator molecules and non-covalent interactions at three distinct nano-locations of the gel network. A β-sheet arrangement is dominant in single and parallel fibres with a small proportion of an α-helix present, while the molecular assembly derives from strong hydrogen bonding. However, at the crossing point of two …
Interaction en champ proche entre une sonde nanométrique et le champ de composants à cristal photonique:- interaction faible, microscopie spatialemen…
2008
With the improvement of fabrication techniques, the nanophotonics and more especially the photonics crystals which are periodic structure at the Wavelength scale have been recently developed. In this work, by using a scanning near-field optical microscope, we study such components. Firslty, we use the local probe to visualize the light distribution inside photonic crystal microcavities etched into semiconductor III/V. We focus us on the explanation of the near-field maps formation and on the probe influence on these maps. Thus, we have visualize degeneracy splitting of optical cavity modes and clearly observed in near-field cavity modes which were not visible in far-field. Moreover, in the …