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Journal of Nanomaterials
Volume 2015, Article ID 672957, 7 pages
http://dx.doi.org/10.1155/2015/672957
Research Article

Elusive Pure Anapole Excitation in Homogenous Spherical Nanoparticles with Radial Anisotropy

1College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073, China
2Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Acton, ACT 0200, Australia

Received 30 August 2015; Accepted 18 October 2015

Academic Editor: Christian Brosseau

Copyright © 2015 Wei Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

For homogenous isotropic dielectric nanospheres with incident plane waves, Cartesian electric and toroidal dipoles can be tunned to cancel each other in terms of far-field scattering, leading to the effective anopole excitation. At the same time however, other multipoles such as magnetic dipoles with comparable scattered power are simultanesouly excited, mixing with the anopole and leading to a nonnegligible total scattering cross-section. Here, we show that, for homogenous dielectric nanospheres, radial anisotropy can be employed to significantly suppress the other multipole excitation, which at the same time does not compromise the property of complete scattering cancallation between Cartesian electric and toroidal dipoles. This enables an elusive pure anopole excitation within radially anisotropic dielectric nanospheres, which may shed new light on many scattering related fundamental researches and applications.