Diameter-bandwidth product limitation of isolated-object cloaking

Hashemi, Hila; Qiu, Cheng‐Wei; McCauley, Alexander P.; Joannopoulos, John D.; Johnson, Steven G.

doi:10.1103/physreva.86.013804

Cited by 43 publications

(32 citation statements)

References 59 publications

(60 reference statements)

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“…In recent work [42] we have bounded the scattering properties of any dissipative medium excited by a known, externally generated incident field. The bounds arise from the functional dependencies of power expressions with respect to induced currents: absorption is a quadratic functional, whereas extinction (absorption+scattering), given by the optical theorem [44][45][46][47], is only a linear functional. Energy conservation requires that extinction be greater than absorption, which imposes a bound on the magnitude of the excited currents.…”

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confidence: 99%

Shape-Independent Limits to Near-Field Radiative Heat Transfer

2015

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We derive shape-independent limits to the spectral radiative heat-transfer rate between two closely spaced bodies, generalizing the concept of a black body to the case of near-field energy transfer. Through conservation of energy and reciprocity, we show that each body of susceptibility χ can emit and absorb radiation at enhanced rates bounded by |χ| 2 / Im χ, optimally mediated by near-field photon transfer proportional to 1/d 2 across a separation distance d. Dipole-dipole and dipole-plate structures approach restricted versions of the limit, but common large-area structures do not exhibit the material enhancement factor and thus fall short of the general limit. By contrast, we find that particle arrays interacting in an idealized Born approximation (i.e., neglecting multiple scattering) exhibit both enhancement factors, suggesting the possibility of orders-of-magnitude improvement beyond previous designs and the potential for radiative heat transfer to be comparable to conductive heat transfer through air at room temperature, and significantly greater at higher temperatures.

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confidence: 99%

Shape-Independent Limits to Near-Field Radiative Heat Transfer

2015

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“…which is similar to the form of the optical theorem given in [34,23,37], and W = 2k 0 π Im[p a P s ∞ (k 0 /k 0 )]/(ωρ 0 ), (7.8) which is the well-known form of the optical theorem [58,15] for acoustic scattering.…”

Section: A Minimization Variational Principle For Acoustic Scatteringmentioning

confidence: 63%

Bounds on complex polarizabilities and a new perspective on scattering by a lossy inclusion

Milton

2017

Phys. Rev. B

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Here we obtain explicit formulae for bounds on the complex electrical polarizability at a given frequency of an inclusion with known volume that follow directly from the quasistatic bounds of Bergman and Milton on the effective complex dielectric constant of a two-phase medium. We also describe how analogous bounds on the orientationally averaged bulk and shear polarizabilities at a given frequency can be obtained from bounds on the effective complex bulk and shear moduli of a two-phase medium obtained by Milton, Gibiansky and Berryman, using the quasistatic variational principles of Cherkaev and Gibiansky. We also show how the polarizability problem and the acoustic scattering problem can both be reformulated in an abstract setting as "Y -problems". In the acoustic scattering context, to avoid explicit introduction of the Sommerfeld radiation condition, we introduce auxilliary fields at infinity and an appropriate "constitutive law" there, which forces the Sommerfeld radiation condition to hold. As a consequence we obtain minimization variational principles for acoustic scattering that can be used to obtain bounds on the complex backwards scattering amplitude. Some explicit elementary bounds are given.

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“…Scattering coefficient study in different cylindrical wave orders have been shown with simplified material properties [11,12]. Until now, discussions on the bandwidth and practical limitations of electromagnetic cloak present in the published results [13][14][15][16][17][18] are few in number.…”

Section: Introductionmentioning

confidence: 96%