Peculiarities of photonic nanojet formation on a spherical cluster of dielectric nanoparticles
Yu.E. Geints, E.K. Panina
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: particle cluster, close packing, photonic nanojet, effective medium approximation, FDTD simulation
Abstract
The results of the numerical simulations on optical radiation focusing by a cluster of identical nanospheres densely packed into a spherical volume (a "metaparticle") are presented. The parameters of the focal region (intensity, longitudinal and transverse dimensions) formed by metaparticles with different internal structure are calculated. We show that in certain cases, the problem of focusing optical radiation by a globular cluster of nanoparticles can be reduced to the problem of light focusing by a homogeneous spherical particle with an effective refractive index obtained from the effective medium theory. Moreover, certain globular cluster topologies make it possible to improve the optical focusing in the near-field region, in particular, by increasing the focal intensity or enhancing the spatial localization of the focal area.
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