Polarimetric response of magnetodielectric core–shell nanoparticles: an analysis of scattering directionality and sensing

Self Cite

High Refractive Index (HRI) dielectric nanoparticles have been proposed as an alternative to metallic ones due to their low absorption and magnetodielectric response in the VIS and NIR ranges. For the latter, important scattering directionality effects can be obtained. Also, systems constituted by dimers of HRI dielectric nanoparticles have shown to produce switching effects by playing with the polarization, frequency or intensity of the incident radiation. Here, we show that scattering directionality effects can be achieved with a single eccentric metallo-HRI dielectric core-shell nanoparticle. As an example, the effect of the metallic core displacements for a single Ag-Si core-shell nanoparticle has been analyzed. We report rotation of the main scattering lobe either clockwise or counterclockwise depending on the polarization of the incident radiation leading to new scattering configurations for switching purposes. Also, the efficiency of the scattering directionality can be enhanced. Finally, chains of these scattering units have shown good radiation guiding effects, and for 1D periodic arrays, redirection of diffracted intensity can be observed as a consequence of blazing effects. The proposed scattering units constitute new blocks for building systems for optical communications, solar energy harvesting devices and light guiding at the nanoscale level.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Light guiding and switching using eccentric core-shell geometries

Barreda

Gutiérrez

Sanz

et al. 2017

Self Cite

“…The geometrical parameters of the design are chosen such that the structure exhibits a magnetic resonance resonance at the operating wavelength of 1550 nm at no-bias condition. In the core-shell/multimaterial nanoparticles, the filling fraction and shell radius of the particles determine the scattering and resonant properties of the layered system 46 , 47 . As such, a parametric study is conducted to determine the required outer radius and filling fraction of the multimaterial nanowire.…”

Section: Resultsmentioning

confidence: 99%

Electrically Tunable Metamaterials Based on Multimaterial Nanowires Incorporating Transparent Conductive Oxides

Salary

Mosallaei

2017

We present novel design approaches for metasurfaces and metamaterials with electrical tunability offering real-time manipulation of light and serving as multifunctional devices in near-infrared frequency regime (at the specific wavelength of 1.55 μm). For this purpose, we integrate indium-tin-oxide (ITO) as a tunable electro-optical material into multimaterial nanowires with metal-oxide-semiconductor and metal-insulator-metal configurations. In particular, an active metasurface operating in the transmission mode is designed which allows for modulation of the transmitted light phase over 280 degrees. This large phase modulation is afforded in the cost of low transmission efficiency. We demonstrate the use of such active metasurfaces for tunable bending and focusing in free-space. Moreover, we investigate the implementation of this material in deeply subwavelength multimaterial nanowires, which can yield strong variations in the effective refractive index by the virtue of internal homogenization enabling tunability of the performance in gradient refractive index metamaterials. In the theoretical modeling of these structures, we adopt a hierarchical multiscale approach by linking drift-diffusion transport model with the electromagnetic model which rigorously characterizes the electro-optical effects.

“…Apart from fundamentally important transformation optics (TO) technique, the plasmonic cloaking (PC) and mantle cloaking (MC) [49][50][51][60][61][62]65,66 are more common from a practical point of view. In literature, different approaches to control the scattering of light are found [67][68][69][70][71][72][73][74][75][76][77] . In particular, MC differs from others since it does not require bulk anisotropic materials and is realized by using a thin layer metasurface usually consisting of a periodic arrangement of unit cells.…”

Section: Discussionmentioning

confidence: 99%

Mantle cloaking due to ideal magnetic dipole scattering

Cappello

Ospanova

Matekovits

et al. 2020

one of the most exciting applications of metaparticles and metasurfaces consists in the magnetic light excitation. However, the principal limitation is due to parasitic extra multipoles of electric family excited in magnetic dipole meta-particles characterized by a radiating nature and corresponding radiating losses. in this paper, we propose the "ideal magnetic dipole" with suppressed additional multipoles except of magnetic dipole moment in the scattered field from a cylindrical object by using mantle cloaking based on metasurface and on anapole concept. the considered metasurface consists of a periodic width modulated microstrip line, with a sinusoidally shaped profile unit cell printed on a dielectric substrate.Despite of the progress in electromagnetics, the light-matter interaction is still associated especially with electric component of light, while magnetic component is suppressed down to negligible level, particularly at more anticipated optical frequencies. On the other hand, magnetic light-matter interaction is promising playground for unusual effects like negative refraction 1-4 , magnetoinductive waves 5 , fluorescent microscopy 6,7 , nanoscale imaging and others 8,9 . Therefore, magnetic response of subwavelength particles contributes to optical magnetism leading to effects such as magnetic light 10 , magnetic nanoantennas 11-15 and magnetic Purcell effect [16][17][18][19] . For this sake, recent works propose various techniques for artificial magnetism that enable strong magnetic field localization even for nonferromagnetic particles that is usually several times weaker than the electric field component counterpart [20][21][22][23][24] . The first realization of artificial magnetic dipole (MD) has been demonstrated in metal split-ring resonator (SRR), thereafter becoming a basic element of metamaterials 3,25,26 . Overall, strongly concentrated magnetic field can be excited by a circular current oscillating within the SRR and mimicking a MD. The idea of SRR is still of high demand; however, its application is restricted by the impossibility of implementation in visible frequency range due to intrinsic metallic particles with high Joule losses 26 . A second limitation is due to the excitation of parasitic extra multipoles of electric family characterized by a radiating nature and corresponding radiating losses. Thus, researchers are approaching to achieve an ideal magnetic dipole without additional multipoles (except of magnetic dipole moment) in the system.The idea of the ideal MD scatterer can be elegantly described by multipole decomposition theory of the scattering from resonant particles. This approach allows studying the radiation properties by description of the scattering cross-section as a sum of electric a E (l, m) and magnetic a M (l, m) scattering coefficients. Indeed, the resulting scattering efficiency Q sca is given by the superposition of electric and magnetic scattered multipoles:where l is the number of spherical harmonics defining multipoles order. In this way, we can calculate th...