Cloaking and magnifying using radial anisotropy

Abstract

This paper studies the electrostatic responses of a polarly radially anisotropic cylinder and a spherically radially anisotropic sphere. For both geometries, the permittivity components differ from each other in the radial and tangential directions. We show that choosing the ratio between these components in a certain way, these rather simple structures can be used in cloaking dielectric inclusions with arbitrary permittivity and shape in the quasi-static limit. For an ideal cloak, the contrast between the permittivity components has to tend to infinity. However, only positive permittivity values are required and a notable cloaking effect can already be observed with relatively moderate permittivity contrasts. Furthermore, we show that the polarly anisotropic cylindrical shell has a complementary capability of magnifying the response of an inner cylinder.

Tailoring Effective Media by Mie Resonances of Radially-Anisotropic Cylinders

“…This can be seen as a continuation from our previous RA studies [40,45], where permittivity ε is always assumed anisotropic. Even though our analysis remains purely theoretical and speculative considering the actual realization of the suggested material configurations, depending on the frequency range, physically-available materials usually offer a wider variety of realizable values for permittivity than for permeability, which also supports choosing this polarization.…”

“…For example, choosing ε ρ = 1 gives ε eff ≈ 1.43. We can even make the lattice electrically transparent by choosing ε ρ = ε −1 ϕ , as found in [40]. Figure 2 presents the obtained µ eff and ε eff using the aforementioned values ε ρ = 1, ε ϕ = 253, µ z = 1, p = 0.2.…”

“…is the geometric average of the RA permittivity components [40,42,43]. This means that from the outside, the anisotropic cylinder is observed effectively isotropic.…”

“…The electrostatic analysis of RA cylinders is considered in [39,40], and the Mie theory is applied for them in [41][42][43]. Papers [41] and [40] consider using cylindrical RA shells for cloaking purposes, whereas [42,43] focus on the peculiarities of light scattering from plasmonic RA cylinders. For the analysis, occurrence and applications of 3D radially-anisotropic spheres, see [44,45] and the references therein.…”

Electret electrostatic cloak

“…Inspired by those theoretical works, varieties of electromagnetic cloak [5][6][7][8][9][10][11], acoustic cloak [12][13][14], matter wave cloak [15], mass diffusion cloak [16], heat cloak [17][18][19][20], magnetic cloak [21][22][23], dc electric cloak [24][25][26] and electrostatic cloak [27] have been theoretically designed and experimentally demonstrated. The first experiment demonstrated invisible cloak using metamaterial with simplified material parameters [5].…”