Material- and geometry-independent multishell cloaking device

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Material- and geometry-independent multishell cloaking device

Pattabhiraju C. Mundru, Venkatesh Pappakrishnan, and Dentcho A. Genov

Phys. Rev. B 85, 045402 – Published 3 January 2012

Abstract

In this paper we propose a multishell generic cloaking system. A transparency condition independent of the object's optical and geometrical properties is proposed in the quasistatic regime of operation. The suppression of dipolar scattering is demonstrated in both cylindrically and spherically symmetric systems. A realistic tunable low-loss shell design is proposed based on a composite metal-dielectric shell. The effects due to dissipation and dispersion on the overall scattering cross section are thoroughly evaluated. It is shown that a strong reduction of scattering by a factor of up to $10^{3}$ can be achieved across the entire optical spectrum. Full wave numerical simulations for complex shaped particles are performed validating the analytical theory. The proposed design does not require optical magnetism and is generic in the sense that it is independent of the object's material and geometrical properties.

Received 4 November 2011

DOI:https://doi.org/10.1103/PhysRevB.85.045402

Authors & Affiliations

Pattabhiraju C. Mundru, Venkatesh Pappakrishnan, and Dentcho A. Genov^*

College of Engineering and Science, Louisiana Tech University, Ruston, Louisiana 71270, USA

^*dgenov@latech.edu

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Issue

Vol. 85, Iss. 4 — 15 January 2012

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Images

Figure 1
(a) Generic multishell cloaking system with shell radii $r_{i}$ and permittivity $ɛ_{i}$ , a two-shell (b) cylindrically symmetric cloaking system and (c) spherically symmetric cloaking system.Reuse & Permissions
Figure 2
Relative scattering length (RSL) and cross section (RSCS) versus outer-shell permittivity for two-shell (a) cylindrically symmetric cloak and (b) spherically symmetric cloak with inner shell made of bulk silver. Two separate designs are being investigated in the case of cylindrical system: (I) $p_{2} = 0.67$ and (II) $p_{2} = 0.82$ , and spherical system (I) $p_{2} = 0.73$ and (II) $p_{2} = 0.86$ . The object permittivity is $ɛ_{0} = 12$ and for all cases we use the optimal radii ratio $p_{1} = 1 / (1 + \sqrt{d})$ . The limiting case as per Eq. (10) is presented with dotted (black) lines.Reuse & Permissions
Figure 3
(a) Depolarization factor for composite host materials $ɛ_{h} = 1$ (solid line) and $ɛ_{h} = 2.0$ (dashed line) at different frequencies and $f = 0.05$ . RSL and RSCS) versus outer-shell permittivity of two-shell (b) cylindrically symmetric cloaking system and (c) spherically symmetric cloaking system, respectively. The composite inner shell is designed with two different hosts, $ɛ_{h} = 1$ (dashed red line) and $ɛ_{h} = 2.0$ (dotted green line) at $ℏ ω = 1.14 eV$ . In the plots we also consider two separate shell designs; cylindrical system (I) $p_{2} = 0.67$ and (II) $p_{2} = 0.82$ , and spherical system (I) $p_{2} = 0.73$ and (II) $p_{2} = 0.86$ . The embeded object has permitivity $ɛ_{0} = 12$ and for all cases we use the optimal shell radii ratio $p_{1} = 1 / (1 + \sqrt{d})$ . The ideal lossless cases are represented with solid (blue) lines. The limiting case [as per Eqs. (9) and (14)] is presented with horizontal (dotted and dashed) black lines for both the host media.Reuse & Permissions
Figure 4
(a) RSL and (b) RSCS calculated as function of outer-shell permittivity ( $ɛ_{2}$ ) and incident light frequency for a dielectric particle $(ɛ_{0} = 12)$ with $ɛ_{h} = 1$ and spheroids volume to surface fraction $f = 0.05$ . The shells’ radii ratios are (a) cylindrical system $(p_{1}, p_{2}) = (0.41, 0.67)$ , and (b) spherical system $(p_{1}, p_{2}) = (0.37, 0.73)$ .Reuse & Permissions
Figure 5
Full wave calculations of the RSL as a function of outer-shell permittivity $(ɛ_{2})$ and incident light frequency for dielectric particle $ɛ_{0} = 12$ (a), (b) and metal particle (c), (d) enclosed in a cloaking system with radii $r_{2} = 50$ nm (a), (c) and $r_{2} = 100$ nm (b), (d).Reuse & Permissions
Figure 6
Full wave calculations of light scattering due to a point source in close proximity to a star-shaped metal object with (a), and without (b) the cloak. The incident TM wave has frequency $ℏ ω = 3.8 eV$ .Reuse & Permissions

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