Homogenization of a multilayer sphere as a radial uniaxial sphere: features and limits

We consider a multilayer sphere with a fixed external radius and with an arbitrary number of layers as a possible realization of a radial uniaxial (RU) sphere. We start from the well-known quasi-static model for the polarizability of the multilayer sphere and, after a validation with a dynamic code previously presented, we try to understand the limits in which the multilayer sphere can be considered a RU sphere. We employ different techniques for layering the spheres and we find which of them is convenient in terms of convergence speed. Moreover, we deal with the case of plasmonic layers and we find some rules for the realization of the multilayer sphere in order to obtain the desired homogenized parameters. Finally, we present a study on the behavior of plasmon resonances of the multilayer sphere when the number of layers is increased.