Enhanced transmission of slit arrays in an extremely thin metallic film

Horizontal resonances of slit arrays are studied. They can lead to an enhanced transmission that cannot be explained using the single-mode approximation. A new type of cavity resonance is found when the slits are narrow for a wavelength very close to the period. It can be excited for very low thicknesses. Optimization shows these structures could constitute interesting monochromatic filters

Theory of fishnet negative-index optical metamaterials

We theoretically study fishnet metamaterials at optical frequencies. In contrast to earlier works, we provide a microscopic description by tracking the transversal and longitudinal flows of energy through the fishnet mesh composed of intersecting subwavelength plasmonic waveguides. The analysis is supported by a semi-analytical model based on surface-plasmon coupled-mode equations, which provides accurate formulas for the fishnet refractive index, including the real-negative and imaginary parts. The model simply explains how the surface plasmons couple at the waveguide intersections and it shines new light on the fishnet negative-index paradigm at optical frequencies. Extension of the theory for loss-compensated metamaterials with gain media is also presented.Comment: 4 figure

On the attenuation coefficient of monomode periodic waveguides

It is widely accepted that, on ensemble average, the transmission T of guided modes decays exponentially with the waveguide length L due to small imperfections, leading to the important figure of merit defined as the attenuation-rate coefficient alpha = -/L. In this letter, we evidence that the exponential-damping law is not valid in general for periodic monomode waveguides, especially as the group velocity decreases. This result that contradicts common beliefs and experimental practices aiming at measuring alpha is supported by a theoretical study of light transport in the limit of very small imperfections, and by numerical results obtained for two waveguide geometries that offer contrasted damping behaviours

Slow-wave effect and mode-profile matching in Photonic Crystal microcavities

Physical mechanisms involved in the light confinement in photonic crystal slab microcavities are investigated. We first present a full three-dimensional numerical study of these microcavities. Then, to gain physical insight into the confinement mechanisms, we develop a Fabry-Perot model. This model provides accurate predictions and sheds new light on the physics of light confinement. We clearly identify two mechanisms to enhance the Q factor of these microcavities. The first one consists in improving the mode-profile matching at the cavity terminations and the second one in using a slow wave in the cavity.Comment: accepted for publication in Phys. Rev. B, 8 pages, 4 figure

Decomposing the scattered field of two-dimensional metaatoms into multipole contributions

We introduce a technique to decompose the scattered near field of two-dimensional arbitrary metaatoms into its multipole contributions. To this end we expand the scattered field upon plane wave illumination into cylindrical harmonics as known from Mie theory. By relating these cylin- drical harmonics to the field radiated by Cartesian multipoles, the contribution of the lowest order electric and magnetic multipoles can be identified. Revealing these multipoles is essential for the design of metamaterials because they largely determine the character of light propagation. In par- ticular, having this information at hand it is straightforward to distinguish between effects that result either from the arrangement of the metaatoms or from their particular design

A microscopic view of the electromagnetic properties of sub-wavelength metallic surfaces

We review the properties of the surface waves that are scattered by two-dimensional sub-wavelength indentations on metallic surfaces. We show that two distinct waves are involved, a surface plasmon polariton (SPP) and a quasi-cylindrical wave (quasi-CW). We discuss the main characteristics of these waves, their damping characteristic lengths and their relative excitation weights as a function of the separation distance from the indentation and as a function of the metal conductivity. In particular we show that derive a closed-form expression for the quasi-CW, which clarifies its physical origin and its main properties. We further present an intuitive microscopic model, which explains how the elementary SPPs and quasi-CWs exchange their energies by multiple-scattering to build up a rich variety of near- and far-field optical effects.Comment: Review article, 98 references. Sur. Sc. Rep. (in press

Sharing the fruits of growth from 1950 to 2008: A surplus-accounting approach

In this paper, we apply the surplus accounting methodology to analyze the distribution of the fruits of growth between production factors over the period 1950-2008. Three production factors are distinguished: paid employment, self-employment and capital. The surplus distributed to capital is nil on average. The employees received a surplus linked to the evolution of total factor productivity, which experienced a slowdown in the 1980s Since 2007, the distributed surplus has sharply dropped, due to an increase in external deduction. The evolution of the surplus is, then, confronted to value-added distribution, by focusing on the capital-labour substitution in the 1980s. The standard framework of surplus accounting is, finally, extended by taking the Welfare System and its financing into account. Indeed, even if the Welfare System is mostly financed by social contributions paid by production factors, social benefits are also distributed to agents who are not involved in the production process, namely the pensioners, the unemployed, and the non-working population. We find that the surplus distributed to employees is lower when social contributions are taken into account. In the meantime, a half-percentage point of the value-added growth rate is assigned each year to the financing of the old-age insurance, whose main part however (0.4 point) accrues tothe growing number of new pensioners. Nevertheless, the incomes after social benefits allocated to the employed, the unemployed, and pensioners grow at a similar pace.Surplus Accounting, Value-Added Distribution, Welfare System, Pensioners