Maximum absorption by homogeneous magneto-dielectric sphere

Michael Forum Palvig, Olav Breinbjerg, Morten Willatzen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

n order to obtain a benchmark for electromagnetic energy harvesting, we investigate the maximum absorption efficiency by a magneto-dielectric homogeneous sphere illuminated by a plane wave, and we arrive at several novel results. For electrically small spheres we show that the optimal relative permeability and permeability of materials where ϵ′r, μ′r≥1 is (1+i3) independent of sphere size, while that of metamaterials is (−2+iδ), where the imaginary part δ decreases strongly with decreasing sphere size. For larger spheres we show that while maximum absorption efficiency occurs at the resonances of the spherical modes, there exists a wide plateau of high absorption efficiency when material intrinsic impedance is constant; in the case of free-space intrinsic impedance and electrical radius κ=1, the absorption efficiency becomes 2.8. The investigation is analytic/numerical and based on the Lorenz–Mie theory combined with the optical theorem.
Original languageEnglish
JournalJournal of the Optical Society of America A
Volume31
Issue number9
Pages (from-to)1912-1918
ISSN0740-3232
DOIs
Publication statusPublished - 2014

Cite this

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title = "Maximum absorption by homogeneous magneto-dielectric sphere",
abstract = "n order to obtain a benchmark for electromagnetic energy harvesting, we investigate the maximum absorption efficiency by a magneto-dielectric homogeneous sphere illuminated by a plane wave, and we arrive at several novel results. For electrically small spheres we show that the optimal relative permeability and permeability of materials where ϵ′r, μ′r≥1 is (1+i3) independent of sphere size, while that of metamaterials is (−2+iδ), where the imaginary part δ decreases strongly with decreasing sphere size. For larger spheres we show that while maximum absorption efficiency occurs at the resonances of the spherical modes, there exists a wide plateau of high absorption efficiency when material intrinsic impedance is constant; in the case of free-space intrinsic impedance and electrical radius κ=1, the absorption efficiency becomes 2.8. The investigation is analytic/numerical and based on the Lorenz–Mie theory combined with the optical theorem.",
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Maximum absorption by homogeneous magneto-dielectric sphere. / Palvig, Michael Forum; Breinbjerg, Olav; Willatzen, Morten.

In: Journal of the Optical Society of America A, Vol. 31, No. 9, 2014, p. 1912-1918.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Maximum absorption by homogeneous magneto-dielectric sphere

AU - Palvig, Michael Forum

AU - Breinbjerg, Olav

AU - Willatzen, Morten

PY - 2014

Y1 - 2014

N2 - n order to obtain a benchmark for electromagnetic energy harvesting, we investigate the maximum absorption efficiency by a magneto-dielectric homogeneous sphere illuminated by a plane wave, and we arrive at several novel results. For electrically small spheres we show that the optimal relative permeability and permeability of materials where ϵ′r, μ′r≥1 is (1+i3) independent of sphere size, while that of metamaterials is (−2+iδ), where the imaginary part δ decreases strongly with decreasing sphere size. For larger spheres we show that while maximum absorption efficiency occurs at the resonances of the spherical modes, there exists a wide plateau of high absorption efficiency when material intrinsic impedance is constant; in the case of free-space intrinsic impedance and electrical radius κ=1, the absorption efficiency becomes 2.8. The investigation is analytic/numerical and based on the Lorenz–Mie theory combined with the optical theorem.

AB - n order to obtain a benchmark for electromagnetic energy harvesting, we investigate the maximum absorption efficiency by a magneto-dielectric homogeneous sphere illuminated by a plane wave, and we arrive at several novel results. For electrically small spheres we show that the optimal relative permeability and permeability of materials where ϵ′r, μ′r≥1 is (1+i3) independent of sphere size, while that of metamaterials is (−2+iδ), where the imaginary part δ decreases strongly with decreasing sphere size. For larger spheres we show that while maximum absorption efficiency occurs at the resonances of the spherical modes, there exists a wide plateau of high absorption efficiency when material intrinsic impedance is constant; in the case of free-space intrinsic impedance and electrical radius κ=1, the absorption efficiency becomes 2.8. The investigation is analytic/numerical and based on the Lorenz–Mie theory combined with the optical theorem.

U2 - 10.1364/JOSAA.31.001912

DO - 10.1364/JOSAA.31.001912

M3 - Journal article

VL - 31

SP - 1912

EP - 1918

JO - Journal of the Optical Society of America A

JF - Journal of the Optical Society of America A

SN - 0740-3232

IS - 9

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