Aude Barbara

• French National Centre for Scientific Research

We present the first non-resonant and non-enhanced Raman correlation spectroscopy experiments. They are conducted on a confocal microscope combined with a Raman spectrometer. The thermal fluctuations of the Raman intensities scattered by dispersions of polystyrene particles of sub-micrometric diameters are measured and analysed by deriving the auto...

Commensurate gratings of deep-metallic grooves have highly localized cavity resonances which do not exist for purely periodic gratings. In this paper we present the experimental dispersion diagram of the resonances of a commensurate grating with three sub-wavelength cavities per period. We observe selective light localization within the cavities, t...

We study the light localization on commensurate arrangements of deep metallic sub-wavelength grooves. We theoretically show that as the degree of commensuration tends to an irrational number new light localization states are produced. These have properties close to that reported for hot spots on disordered surfaces and are not permitted for simple...

It is theoretically shown that nanometric silver lamellar gratings present very strong visible light absorption inside the grooves, leading to electric field enhancement of several orders of magnitude. It is due to the excitation of quasistatic surface plasmon polaritons with particular small penetration depth in the metal. This may explain the abn...

We have developed a bright optical setup, especially optimized for surface-enhanced Raman scattering (SERS) correlation spectroscopy. We show that the brightness of the experiment combined with the correlation approach permits in situ access to the size and shape of the SERS-active aggregates in solution despite a very weak SERS signal of the adsor...

The coupling distance between two narrow resonating slits made in a thick metal screen strongly modulates the optical spectral features of their scattering resonances. We show that these non-trivial modulations result from dipolar-type interactions between the slits. The radiation damping, frequency shift and local light enhancement of these modes...

We describe a setup including a microscope to study volumes of a few μm 3 by static and dynamic light scattering (DLS) in a backscattering configuration. Light scattered by individual objects of micrometric size can be analyzed in the 400 – 800 nm spectral range. This setup can also be employed to study both diluted and concentrated colloidal solut...

A method to elaborate micro-structures of ionic crystals based on the deposition of drops on a surface with a capillary is presented. The typical dimension of these structures is in the micron range. The possible applications of such structures in optics are discussed. Presentamos un método para elaborar microestructuras de cristales iónicos que se...

We consider a zero-order diffraction metallic grating having two subwavelength rectangular slits per period. The electromagnetic behavior of this system is studied theoretically in the resonance spectral domain of the cavities. We show that, by choosing judicious opto-geometrical parameters, we can perform the selective excitation of one or the oth...

Light localization on commensurate arrangements of metallic sub-wavelength grooves is studied. We theoretically show that as the degree of commensuration tends to an irrational number new light localization states are produced. These have properties close to that reported for hot spots on disordered surfaces and are not permitted for simple period...

Nous présentons la modélisation du champ électromagnétique dans un réseaux métalliques sub-longueur d'onde. L'influence du diélectrique couvrant les cavités sera étudiée à l'aide de diagrammes de dispersion et de cartes de champs. Nos calculs seront validés par des mesures de réflectivité en fonction de l'angle d'incidence.

It is theoretically shown that nanometric silver lamellar gratings present very strong visible light absorption inside the grooves, leading to electric field intensities by several orders of magnitude larger than that of the impinging light. This effect, due to the excitation of long wave vector surface plasmon polaritons with particular small pene...

We investigate the optical response of two subwavelength grooves on a metallic screen, separated by a subwavelength distance. We show that the cavity, Fabry-Perot-like mode, already observed in one-dimensional periodic gratings and known for a single slit, splits into two resonances in our system: a symmetric mode with a small Q factor, and an anti...

We provide experimental evidence of an improved excitation of the cavity modes of deep lamellar metallic gratings by using an attenuated total reflection configuration. The reflectivity of gold gratings composed of 1-μ m deep channels, with width of 0.7 μ m , periodically separated by a distance of 1.75 μ m was measured in the 1000–5000- cm <sup>-1...

One-dimensional rectangular metallic gratings enable enhanced transmission of light for specific resonance frequencies. Two kinds of modes participating in enhanced transmission have already been demonstrated: waveguide modes and surface plasmon polaritons. Since the original article by Hessel and Oliner Appl. Opt. 4, 1275 1965 pointing out the exi...

A homemade apertureless near-field optical microscope using a scanning tunneling microscope (STM) is described. The experimental set-up simultaneously provides optical and topographic images of the sample. Technical details and features of the set-up are presented, together with results demonstrating the sub-wavelength resolution achieved as well a...

A method to elaborate micro-structures of ionic crystals based on the deposition of drops on a surface with a capillary is presented. The typical dimension of these structures is in the micron range. The possible applications of such structures in optics are discussed.

A method to elaborate micro-structures of ionic crystals based on the deposition of drops on a surface with a capillary is presented. The typical dimension of these structures is in the micron range. The possible applications of such structures in optics are discussed.

We present a theoretical and experimental study of electromagnetic modes of 1D sub-wavelength rectangular metallic gratings exposed to P-polarized light. Reflection properties of gratings composed of deep grooves and transmission resonances of gratings composed of deep slits were both examined. Calculations were made using the modal development pro...

We present measurements of enhanced resonant transmission of infrared radiation through subwavlength metallic gratins made of rectangular grooves. This is achieved either by exciting a resonant waveguide mode in the cavities, or when the field is large enough above the groove, which is particular satisfied close to surface plasmons excitation condi...

In this work, X-ray absorption spectroscopy, and more precisely Extended X-ray Absorption Fine Structure (EXAFS), was used to determine the atomic structure of Mn films with various thicknesses deposited on (111) and (100) Ir lattices via molecular beam epitaxy. The goal is to reach new magnetic properties by forcing a material to a specific atomic...

X-ray anomalous diffraction in different geometries and X-ray resonant magnetic scattering have been used to investigate FexMn1−x/Ir(001) superlattices. The influence of the alloy stoichiometry on the structural and magnetic properties has been studied and compared with the bulk alloy properties. The structural results are compared with the magneti...

X-ray anomalous scattering has been used for the selective characterisation of the structure of each sublattice in Fe/Ir (001) superlattices. The data have been analysed by comparing the simulated and experimental spectra in q-space at various wavelengths near the absorption edges. This approach, applied to symmetric reflection scans, enables a mod...

The analysis of the growth, structure, and magnetic properties of iron in (001) FeIr superlattices grown by molecular beam epitaxy is presented. The growth was analyzed by reflection high-energy electron diffraction (RHEED), and the morphology of the superlattices observed by transmission electron microscopy and low-angle x-ray diffraction. The str...