Search results for "Microscopy"
showing 10 items of 3390 documents
Near-field observation of subwavelength confinement of photoluminescence by a photonic crystal microcavity
2006
We present a direct, room-temperature near-field optical study of light confinement by a subwavelength defect microcavity in a photonic crystal slab containing quantum-well sources. The observations are compared with three-dimensional finite-difference time-domain calculations, and excellent agreement is found. Moreover, we use a subwavelength cavity to study the influence of a near-field probe on the imaging of localized optical modes. © 2006 Optical Society of America.
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.
Progress in the interpretation of near-field optics
1998
International audience
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 …
Background-free nonlinear Raman microscopy and spectroscopy at interfaces
2010
Gaussian focused beams exhibit specific properties that drive the emitted fields in nonlinear optical microscopy. We discuss here how the basic field and object symmetry properties can be favorably used to obtain background-free images and spectra in third-order nonlinear optical processes. We concentrate here on coherent anti-Stokes Raman scattering (CARS), the non-linear analogue of Raman scattering. In CARS microscopy, the vibrational related (“resonant”) signal is often overwhelmed by an electronic related (“nonresonant”) background. Various strategies have been implemented to circumvent the undesirable effects of this nonresonant background: picosecond pulse excitation, time resolved, …
Generic nature of long-range repulsion mechanism on a bulk insulator?
2017
Dynamic atomic force microscopy measurements are reported that provide evidence for the presence of long-range repulsion in molecular self-assembly on a bulk insulator surface. We present the structures formed from four different benzoic acid derivatives on the (10.4) cleavage plane of calcite kept in ultra-high vacuum. These molecules have in common that they self-assemble into molecular stripes when deposited onto the surface held at room temperature. For all molecules tested, a detailed analysis of the stripe-to-stripe distance distribution reveals a clear deviation from what would be expected for randomly placed, non-interacting stripes (i.e., geometric distribution). When excluding kin…
Growth of zinc-blende GaN on muscovite mica by molecular beam epitaxy
2021
Abstract The mechanisms of plasma-assisted molecular beam epitaxial growth of GaN on muscovite mica were investigated. Using a battery of techniques, including scanning and transmission electron microscopy, atomic force microscopy, cathodoluminescence, Raman spectroscopy and x-ray diffraction, it was possible to establish that, in spite of the lattice symmetry mismatch, GaN grows in epitaxial relationship with mica, with the [11–20] GaN direction parallel to [010] direction of mica. GaN layers could be easily detached from the substrate via the delamination of the upper layers of the mica itself, discarding the hypothesis of a van der Waals growth mode. Mixture of wurtzite (hexagonal) and z…
A mucosal pellicle modifies the physical properties of epithelial
2017
International audience
International Scanning Probe Microscopy Conference
2016
International audience