Suppression of Scattering for Small Dielectric Particles: Anapole Mode and Invisibility

In 1962, Peter Uiimtsev proposed the idea of implementing invisibility using a special geometric shape of the body that minimizes backscattering [1]. Such a configuration can be realized, for example, with a conical mirror directed towards the light source. The practical implementation of this idea led to the creation of stealth technology. Another idea was proposed in 1983 by M. Kerker. It is based on the use of optical materials with ε = μ [2]. The next step was the idea of an optical transformation based on Fermat’s principle. Inhomogeneous media with special profiles of dielectric and magnetic permeability (ε = ε (r) and μ = μ (r)) make it possible to “direct” light around the masking area [3, 4]. In the literature, the ideas of scattering suppression were also considered, based on multilayer metamaterials in the form of plasmonic and dielectric coatings [5, 6], as well as special dielectric structures realizing anapole states [7, 8] and bound states in a continuum [9]. It is possible to study the problem of scattering suppression by selecting a special radiation polarization, in which the scattered field lies in the region of invisible modes [10]. The second part of this problem is devoted to investigating the minimization of scattering by varying the shape and refractive index of the particle, which ensure the suppression of scattering in the case of a plane electromagnetic wave falling on the particle. An analytical study of scattering minimization is supposed to be carried out by the method of the so-called extended boundary conditions (the T-matrix method) [11] and the surface perturbation method [12], using the theory of perturbation of the particle surface with respect to a spherical one.