Propagation of localized surface plasmons in sets of metallic nanocylinders at the exit of subwavelength slits

We analyze, by means of numerical simulations, transmission enhancements through sub- wavelength slits due to the presence of sets of plasmonic nanocylinders, placed near the exit of these apertures. Further, we extend this study to photonic crystals of dipolar plasmonic particles in front of an array of extraordinarily transmitting slits practiced in a metallic slab.Comment: 20 pages, 9 figures. Submitted to Journal of Nanophotonic

Losses for microwave transmission in metamaterials for producing left-handed materials: The strip wires

This paper shows that the effective dielectric permitivity for the metamaterials used so far to obtain left-handed materials, with strip wires 0.003cm thick, is dominated by the imaginary part at 10.6- 11.5 GHz frequencies, where the band pass filter is, and therefore there is not propagation and the wave is inhomogeneous inside the medium. This is shown from finite-differences time-domain calculations using the real permitivity values for the Cu wires. For thicker wires the losses are reduced and the negative part of the permitivity dominates. As the thickness of the wires is critical for the realization of a good transparent left- handed material we propose that the strip wires should have thickness of 0.07-0.1cm and the split ring resonators 0.015-0.03c

Electromagnetic scattering from very rough random surfaces and deep reflection gratings

A theoretical study of electromagnetic wave scattering from deep perfectly conducting one-dimensional random rough surfaces and reflection gratings is performed by means of the extinction theorem. The scattering equations are solved numerically (instead of being solved by the usual analytical procedures, which are valid only for slight corrugations). This permits us to obtain an exhaustive collection of results for the mean scattered intensity as a function of polarization and surface parameters. In particular, Lambertian scattering and enhanced backscattering are predicted for random surfaces. Also, the range of validity of the Kirchhoff approximation is established for random surfaces whose correlation length is comparable with or smaller than the wavelength. Concerning gratings, random surfaces whose correlation length is comparable with or smaller than the wavelength. Concerning gratings, is shown that the blaze of the antispecular order for gratings is at the root of the enhanced backscattering for random surfaces. © 1989 Optical Society of AmericaThis research was supported by the Comisión Interministerial de Ciencia y Tecnología under grant PB0278.Peer Reviewe

Optical forces from an evanescent wave on a magnetodielectric small particle

We report the first study on the optical force exerted by an evanescent wave on a small sphere with both electric and magnetic response to the incident field, immersed in an arbitrary nondissipative medium. New expressions and effects from their gradient, radiation pressure, and curl components are obtained due to the particle induced electric and magnetic dipoles, as well as to their mutual interaction. We predict possible dramatic changes in the force depending on either the host medium, the polarization and the nature of the surface wave

Near-field distributions of resonant modes in small dielectric objects on flat surfaces

[EN] We report numerical simulations of the coupling of waves, either propagating or evanescent, with the eigenmodes of dielectric nanocylinders and nanospheres upon substrates. The multiple interaction of light between these objects and the dielectric surface at which the evanescent waves are created is taken into account. In this way, we present an accurate procedure for predicting and controlling the creation of large field enhancements concentrated both within and near the nanoparticle compared with the angle of incidence and the state of polarization.This research was supported by the Fundacion Ramon Areces and the European Union. J. R. Arias-Gonzalez acknowledges a scholarship from the Comunidad Autonoma de Madrid.Arias-Gonzalez, JR.; Nieto-Vesperinas, M. (2000). Near-field distributions of resonant modes in small dielectric objects on flat surfaces. Optics Letters. 25(11):782-784. https://doi.org/10.1364/OL.25.000782782784251

Magnetic noise around metallic microstructures

We compute the local spectrum of the magnetic field near a metallic microstructure at finite temperature. Our main focus is on deviations from a plane-layered geometry for which we review the main properties. Arbitrary geometries are handled with the help of numerical calculations based on surface integral equations. The magnetic noise shows a significant polarization anisotropy above flat wires with finite lateral width, in stark contrast to an infinitely wide wire. Within the limits of a two-dimensional setting, our results provide accurate estimates for loss and dephasing rates in so-called `atom chip traps' based on metallic wires. A simple approximation based on the incoherent summation of local current elements gives qualitative agreement with the numerics, but fails to describe current correlations among neighboring objects.Comment: 10 pages, 9 figures, accepted for publication in J Appl Phys; figures plotted for slightly smaller structur