Search results for "Artificially engineered materials"

showing 3 items of 3 documents

Subwavelength Bessel beams in wire media

2013

Recent progress is emerging on nondiffracting subwavelength fields propagating in complex plasmonic nanostructures. In this paper, we present a thorough discussion on diffraction-free localized solutions of Maxwell’s equations in a periodic structure composed of nanowires. This self-focusing mechanism differs from others previously reported, which lie on regimes with ultraflat spatial dispersion. By means of the Maxwell–Garnett model, we provide a general analytical expression of the electromagnetic fields that can propagate along the direction of the cylinder’s axis, keeping its transverse waveform unaltered. Numerical simulations based on the finite element method support our analytical a…

DiffractionElectromagnetic fieldPhysicsTotal internal reflectionbusiness.industryWave propagationEffective medium theoryPhysics::OpticsStatistical and Nonlinear PhysicsAtomic and Molecular Physics and OpticsFinite element methodsymbols.namesakeArtificially engineered materialsOpticsDiffraction theoryDispersion (optics)symbolsCylinderbusinessBessel functionÓpticaJournal of the Optical Society of America B
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Subwavelength beams with polarization singularities in plasmonic metamaterials

2014

We investigated the diffraction behavior of plasmonic Bessel beams propagating in metal-dielectric stratified materials and wire media. Our results reveal various regimes in which polarization singularities are selectively maintained. This polarization-pass effect can be controlled by appropriately setting the filling factor of the metallic inclusions and its internal periodic distribution. These results may have implications in the development of devices at the nanoscale level for manipulation of polarization and angular momentum of cylindrical vector beams. This research was funded by the Spanish Ministry of Economy and Competitiveness under the project TEC2011-29120-C05-01.

DiffractionPhysicsAngular momentumFilling factorbusiness.industryCondensed Matter PhysicsPolarization (waves)Atomic and Molecular Physics and Opticssymbols.namesakeOpticsArtificially engineered materialssymbolsGravitational singularitybusinessNanoscopic scaleDiffractionMathematical PhysicsBessel functionPlasmonSingular opticsÓptica
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Accelerating wide-angle converging waves in the near field

2014

We show that a wide-angle converging wave may be transformed into a shape-preserving accelerating beam having a beam-width near the diffraction limit. For that purpose, we followed a strategy that is particularly conceived for the acceleration of nonparaxial laser beams, in contrast to the well-known method by Siviloglou et al (2007 Phys. Rev. Lett. 99 213901). The concept of optical near-field shaping is applied to the design of non-flat ultra-narrow diffractive optical elements. The engineered curvilinear caustic can be set up by the beam emerging from a dynamic assembly of elementary gratings, the latter enabling to modify the effective refractive index of the metamaterial as it is arran…

DiffractionPhysicsCurvilinear coordinatesbusiness.industryPhysics::OpticsMetamaterialNear and far fieldInvariant optical fieldsAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic MaterialsAccelerationArtificially engineered materialsOpticsDiffraction theoryBroadbandCaustic (optics)businessBeam (structure)ÓpticaJournal of Optics
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