We study both experimentally and numerically far-field radiation patterns of single metallic nanowires coupled
to weak confined optical waveguides. The radiation pattern resulting from the interaction of the nanowire and
the optical mode depends strongly on the mode properties (polarization and wavenumber) and on the antenna
properties (material and size). To investigate these phenomena we compare the electric far-field distributions
computed with different numerical methods (Green's tensor technique, rigourous coupled wave method, Fourier
modal method). We also compare simulated results to experimental measurements obtained over a large spectral
domain ranging from 400 nm to 1000 nm. This study should be useful for optimizing nanostructured photonic
circuits elements.
In the field of microelectronic industry, periodic structures are produced with spatial dimensions that can be less than
100 nm. Because of the material and process effects, these structures will most likely present some additional roughness.
The optical far field characterization of these structures usually allows to deduce the shape parameters of the periodic
structure. Measurements are performed thanks to an ellipsometric apparatus, associated with modelling and inversion
algorithms. In this configuration the technique is called "scatterometry". This method does not permit to directly extract
roughness parameters. This paper aims at describing how model and experimental tools can be used to characterize the
roughness of gratings. The study needs a complete three-dimensional electromagnetic modelling of the structure but the
calculations are very time consuming. Here, different theoretical models are associated in order to reduce the calculation
time: rigorous numerical differential theory and Born approximation theory. The exact numerical model allows to treat
the periodic part of the structure while the roughness is viewed as a perturbation and treated using a first order
approximation. From an experimental point of view, the information on the periodic part of the structure lies in the
diffraction orders, while the roughness signature is mainly found between diffraction orders. Practically, this model
could be used in the semiconductor industry for a detailed roughness characterization, based on an optical measurement
using the same test structures used for scatterometry.
Angle-resolved ellipsometric data are recorded on light scattering and provide a real time process for selective imaging
in scattering media. Surface and bulk effects are separated and could be used for a selective screening inside the tissues.
A recent optical technique is reviewed to identify the scattering origins (surface roughness or bulk heterogeneities) and
eliminate scattering sources in a selective way. Applications concern the field of optical interference coatings, remote
sensing and imaging in random media.
Far field light scattering from rough surfaces and inhomogeneous bulks has extensively been studied these last decades, with a major application in random media characterization. Angular Resolved measurements are performed and investigated thanks to the development of electromagnetic models. The studies are extended to the case of high angular resolution, that's mean to the speckle pattern. We show that the analysis of the polarization state of the scattered field permits to complete this study and to identify signatures of the different polarization sources which are surfaces or bulks. An application will then be to annul each scattering source in order to select the characterized element.
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