A generalized Kerker condition for highly directive nanoantennas

Alaee, Rasoul; Filter, Robert; Lehr, Dennis; Lederer, F.; Rockstuhl, Carsten

doi:10.1364/ol.40.002645

Cited by 234 publications

(239 citation statements)

References 42 publications

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“…Based on Mie theory and the complex refractive index reported for liquid Ga, one can expect that the ED and electric quadrupole (EQ) resonances of a liquid Ga NS will be shifted from the ultraviolet to visible light and even near‐infrared spectral region with increasing diameter of the liquid Ga NS (see , Supporting Information). Therefore, it is quite interesting to study the coherent interaction between the ED and EQ of a liquid Ga NS, which may lead to highly directional radiation based on the generalized Kerker's condition . More importantly, the redshift of the ED resonance to the visible light and near‐infrared spectral region offers us the opportunity to explore the nonlinear optical responses of liquid Ga NSs under the excitation of femtosecond laser pulses.…”

Section: Introductionmentioning

confidence: 99%

Liquid Gallium Nanospheres Emitting White Light

Xiang

Chen

Jiang

et al. 2019

Laser & Photonics Reviews

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Gallium (Ga) is not only a metal possessing surface plasmon resonance in the ultraviolet region but also a phase‐change material with very low melting point. Spherical Ga nanoparticles composed of liquid Ga cores and solid Ga2O3 shells, which exhibit surface plasmonic resonances spanning the ultraviolet to near‐infrared spectral region, are fabricated by using femtosecond laser ablation. Under the excitation of femtosecond laser light, only second harmonic generation is observed in the Ga nanospheres placed on a glass substrate. In sharp contrast, white light emission can be generated in such Ga nanospheres when they are placed on a thin silver film. It is revealed numerically and confirmed experimentally that a Fano resonance originating from the interference between the mirror‐image‐induced magnetic dipole mode and the gap plasmon mode is formed in the backward scattering spectra of the Ga nanospheres. Efficient white light emission can be achieved by resonantly exciting either the magnetic dipole resonance or the Fano resonance. Based on spectral analysis, the white light emission is identified as the hot‐electron intraband luminescence. The fabricated core–shell Ga nanospheres provide an ideal platform on which the optical properties and practical applications of liquid Ga nanoparticles can be systematically investigated.

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Section: Introductionmentioning

confidence: 99%

Liquid Gallium Nanospheres Emitting White Light

Xiang

Chen

Jiang

et al. 2019

Laser & Photonics Reviews

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“…Plasmonic or highindex dielectric nanoparticles are frequently used for this purpose 1,2 . The multipole expansion provides insight into several optical phenomena, such as Fano resonances 3,4 , electromagnetically-induced-transparency 5 , directional light emission [6][7][8][9] , manipulating and controlling spontaneous emission [10][11][12] , light perfect absorption [13][14][15] , electromagnetic cloaking 16,17 , and optical (pulling, pushing, and lateral) forces [18][19][20][21][22] . In all these cases, an external field induces displacement or conductive currents into the samples.…”

mentioning

confidence: 99%

An electromagnetic multipole expansion beyond the long-wavelength approximation

Alaee

Rockstuhl

Fernandez‐Corbaton

2018

Optics Communications

351

313

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The multipole expansion is a key tool in the study of light-matter interactions. All the information about the radiation of and coupling to electromagnetic fields of a given charge-density distribution is condensed into few numbers: The multipole moments of the source. These numbers are frequently computed with expressions obtained after the long-wavelength approximation. Here, we derive exact expressions for the multipole moments of dynamic sources that resemble in their simplicity their approximate counterparts. We validate our new expressions against analytical results for a spherical source, and then use them to calculate the induced moments for some selected sources with a nontrivial shape. The comparison of the results to those obtained with approximate expressions shows a considerable disagreement even for sources of subwavelength size. Our expressions are relevant for any scientific area dealing with the interaction between the electromagnetic field and material systems.PACS numbers: 78.67. Pt, 13.40.Em,78.67.Bf, 03.50.De The multipolar decomposition of a given chargecurrent distribution is taught in every undergraduate course in physics. The resulting set of numbers are called the multipolar moments. They are classified according to their order, i.e. dipoles, quadrupoles etc... For each order, there are electric and magnetic multipolar moments. Each multipolar moment is uniquely connected to a corresponding multipolar field. Their importance stems from the fact that the multipolar moments of a charge-current distribution completely characterize both the radiation of electromagnetic fields by the source, and the coupling of external fields onto it. The multipolar decomposition is important in any scientific area dealing with the interaction between the electromagnetic field and material systems. In particle physics, the multipole moments of the nuclei provide information on the distribution of charges inside the nucleus. In chemistry, the dipole and quadrupolar polarizabilities of a molecule determine most of its properties. In electrical engineering, the multipole expansion is used to quantify the radiation from antennas. And the list goes on.In this Letter, we present new exact expressions for the multipolar decomposition of an electric charge-current distribution. They provide a straightforward path for upgrading analytical and numerical models currently using the long-wavelength approximation. After the upgrade, the models become exact. The expressions that we provide are directly applicable to the many areas where the multipole decomposition of electrical current density distributions is used. For the sake of concreteness, in this article we apply them to a specific field: Nanophotonics.In nanophotonics, one purpose is to control and manipulate light on the nanoscale. Plasmonic or highindex dielectric nanoparticles are frequently used for this purpose 1,2 . The multipole expansion provides insight into several optical phenomena, such as Fano resonances 3,4 , electromagnetically-induced-transparen...

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“…Equation (26), originally calculated for spheres, is not restricted to low densities of scatterers [42] and can successfully be applied to cylinders [49]. In the following, we analytically calculate W/W 0 for a gyrotropic coated cylinder for both p and s waves.…”

Section: B Lorenz-mie Efficiencies and Multiple Scatteringmentioning

confidence: 99%

“…The observation of Kerker conditions relies on the interference of electric and magnetic dipoles in nanostructures [24,25]. Alternative theoretical approaches for Kerker conditions, involving electric dipoles and quadrupoles, also exist [26]. Recently, both broadband zero backward and near-zero forward scattering have been obtained even beyond the dipole limit, relaxing design constraints in practical experiments [27].…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic energy and negative asymmetry parameters in coated magneto-optical cylinders: Applications to tunable light transport in disordered systems

2016

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We investigate electromagnetic scattering of normally irradiated gyrotropic, magneto-optical coreshell cylinders using Lorenz-Mie theory. A general expression for time-averaged electromagnetic energy inside a coated gyroelectric and gyromagnetic scatterer is derived. Using realistic material parameters for a silica core and InSb shell, we calculate the stored electromagnetic energy and the scattering anisotropy. We show that the application of an external magnetic field along the cylinder axis induces a drastic decrease in electromagnetic absorption in a frequency range in the terahertz, where absorption is maximal in the absence of the magnetic field. We demonstrate not only that the scattering anisotropy can be externally tuned by applying a magnetic field, but also that it reaches negative values in the terahertz range even in the dipolar regime. We also show that this preferential backscattering response results in an anomalous regime of multiple light scattering from a collection of magneto-optical core-shell cylinders, in which the extinction mean free path is longer than the transport mean free path. By additionally calculating the energy-transport velocity and diffusion coefficient, we demonstrate an unprecedented degree of external control of multiple light scattering, which can be achieved by either applying an external magnetic field or varying the temperature.

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A generalized Kerker condition for highly directive nanoantennas

Cited by 234 publications

References 42 publications

Liquid Gallium Nanospheres Emitting White Light

Liquid Gallium Nanospheres Emitting White Light

An electromagnetic multipole expansion beyond the long-wavelength approximation

Electromagnetic energy and negative asymmetry parameters in coated magneto-optical cylinders: Applications to tunable light transport in disordered systems

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