High-refractive index dielectric nanoparticles may exhibit strong directionalforward light scattering at visible and near-infrared wavelengths due tointerference of simultaneously excited electric and magnetic dipole resonances.For a spherical high-index dielectric, the so-called first Kerker's conditioncan be realized, at which the backward scattering practically vanishes for somecombination of refractive index and particle size. However, Kerker's conditionfor spherical particles is only possible at the tail of the scatteringresonances, when the particle scatters light weakly. Here we demonstrate thatsignificantly higher forward scattering can be realized if spheroidal particlesare considered instead. For each value of refractive index exists an optimumshape of the particle, which produces minimum backscattering efficiencytogether with maximum forward scattering. This effect is achieved due to theoverlapping of magnetic and electric dipole resonances of the spheroidalparticle at the resonance frequency. It permits the design of very efficient,low-loss optical nanoantennas.
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