Rainbow trapping of guided waves

We study theoretically the propagation of a wave packet that is a superposition of three s-polarized guided waves with different frequencies in a planar waveguide consisting of a dielectric medium with a graded index of refraction, sandwiched between perfectly conducting walls. The electric field at each point within the waveguide is calculated, and it is shown that each of the constituent modes ceases to propagate at a specific distance along the waveguide that depends on its frequency and on the geometrical and material parameters defining the waveguide. This simple model displays the phenomenon of rainbow trapping of guided waves in an explicit fashion, without the use of a negative index metamaterial

The scattering of surface plasmon polaritons by nanoscale surface defects

A rigorous computational approach based on Green's second integral identity in the plane is used to calculate the transmission, reflection, and conversion into volume electromagnetic waves of a surface plasmon polariton incident on a nanoscale one-dimensional surface defect on an otherwise planar interface between vacuum and a lossy metal

Guided Modes in Negative Refractive Index Waveguides

We study linear guided waves propagating in a slab waveguide made of a negative-refraction- index material, the so-called left-handed waveguide. We reveal that the guided waves in left-handed waveguides possess a number of peculiar properties, such as the absence of the fundamental modes, mode double degeneracy, and sign-varying energy ux. In particular, we predict the existence of novel types of guided waves with a dipole-vortex structure of the Pointing vector.Comment: 4 pages, 4 figure

Spectral Dependence of Polarized Radiation due to Spatial Correlations

We study the polarization of light emitted by spatially correlated sources. We show that in general polarization acquires nontrivial spectral dependence due to spatial correlations. The spectral dependence is found to be absent only for a special class of sources where the correlation length scales as the wavelength of light. We further study the cross correlations between two spatially distinct points that are generated due to propagation. It is found that such cross correlation leads to sufficiently strong spectral dependence of polarization which can be measured experimentally.Comment: 5 pages, 4 figure

SPECTROSCOPY OF SURFACE POLARITON DIFFRACTION

On étudie une large gamme d'effets apparaissant quand des ondes électromagnétiques de surface (polaritons de surface) sont diffratées par le bord d'un film diélectrique ou semi-conducteur déposé sur un métal.A wide range of effects arising at diffraction of surface electromagnetic waves (surface polaritons) at the edge of a dielectric or semiconductor film deposited on metal is discussed

NEW TYPES OF LOCAL RESONANCES IN THIN ROUGH FILM

Nous avons prédit de nouveaux types de résonances localisées dans un film mince rugueux déposé sur un substrat. Les résonances localisées du premier type sont associées à une interaction dipôle-dipôle à longue portée. Nous avons trouvé une équation intégrale simple qui tient compte d'une telle interaction. Pour un film d'épaisseur constante, la solution de cette équation correspond à l'onde de surface dont la loi de dispersion non analytique par rapport au vecteur d'onde [MATH], contient un terme proportionnel à |[MATH]|. Lorsqu'un creux existe dans le film, cette équation a des solutions localisées, correspondant à des vibrations localisées de la polarisation. L'extension spatiale de l'état localisé peut être considérablement plus faible que la taille du creux. Les fréquences des vibrations localisées forment une suite équidistante. Les résonances localisées du second type apparaissent lorsqu'on tient compte de la dispersion spatiale dans le film. Les fréquences de ces résonances localisées sont fonction du profil du film et forment une suite équidistante si le film présente une bosse dont le profil peut être représenté par une fonction Gaussienne. La recherche des résonances localisées ainsi prédites semble être d'importance dans l'étude des phénomènes optiques de surface.We have predicted new types of local resonances in a thin rough film on a substrate. The local resonances of the first type are connected with a long-range dipole-dipole interaction. We have derived a simple integral equation which has included such an interaction. For the film of constant thickness the solution of the equation corresponds to the surface wave whose dispersion law is nonanalytic in the wave vector [MATH] and contains the term ~ |[MATH]|. In the case when there is a dip in the film the equation has local solutions which correspond to the local vibrations of polarization. The spatial size of the local state may be considerably smaller than the size of the dip. The frequencies of local vibrations form an equidistant set. The local resonances of the second type appear when spatial dispersion in the film is taken into account. The frequencies of these local resonances depend on the film profile function and form an equidistant set if there is a bump in the film with Gauss profile function. The investigation of predicted local resonances seems to be important for the study of surface optical phenomena