Experimental Evidence of Zero Forward Scattering by Magnetic Spheres

Mehta, R. V.; Patel, Rajesh; Desai, Rucha; Upadhyay, R. V.; Parekh, Kinnari

doi:10.1103/physrevlett.96.127402

Cited by 61 publications

(45 citation statements)

References 17 publications

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“…In this case, these scattering coefficients are usually approximated by their first-order Taylor expansion [11][12][13][14][15][16]:…”

Section: Quasi-static Limit and The Zero-forward Scattering Conditionmentioning

confidence: 99%

“…, without necessarily making both of them zero, which is indeed possible using (14) in combination with (1). This ensures that the overall scattering may be significantly different from zero, despite its zero in the forward direction.…”

Section: Quasi-static Limit and The Zero-forward Scattering Conditionmentioning

confidence: 99%

“…Although this condition was derived in the ideal quasistatic limit, it has been predicted that it may also hold for moderately sized magnetodielectric spheres in a fully dynamic scenario. In fact, renewed interest in this topic has been reported in recent theoretical [12][13] and experimental [14][15][16] papers on the topic. One puzzling aspect of this anomalous scattering feature, surprisingly not addressed in all the aforementioned works, but raised in a recent comment [16], resides in the apparent violation of the fundamental theorem of optics (i.e., the optical theorem) that relates the total extinction cross section of an object ext σ (sum of absorption and scattering cross sections) to the normalized scattering amplitude polarized in parallel with the impinging field in the forward direction ( )…”

Section: Introductionmentioning

confidence: 99%

“…(1), however, allows canceling only the forward scattering of the sphere in the quasi-static limit, implying that it may still be possible to achieve a significantly larger scattering in all other directions. This apparent incongruence was first outlined in a sentence of [16], in which the validity of the experimental evidence presented in [14] was seriously argued against. In the following, we address this issue by reviewing the general theory of scattering from magnetodielectric particles, and we show that Kerker's original theory is indeed valid in the quasi-static limit, without necessarily violating the optical theorem.…”

Section: Introductionmentioning

confidence: 99%

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How does zero forward-scattering in magnetodielectric nanoparticles comply with the optical theorem?

Alù

Engheta

2010

J. Nanophoton

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A few decades ago, Kerker et al. [J. Opt. Soc. Am. 73, 765-767 (1983)] theoretically pointed out the interesting possibility of conceiving small magnetodielectric spheres that may provide zero scattering in the forward direction, despite significantly larger scattering in any other direction. Recent experimental and theoretical papers on the topic have further discussed this possibility in more realistic scenarios. Inspecting some of their analyses, it seems indeed possible to conceive nanoparticles characterized by a scattering pattern with a sharp minimum, although not zero, in the forward direction. From a theoretical standpoint, however, it is well known that the total scattered power from any object has to be proportional to a portion of the scattered field in the forward direction, implying that very small or zero forward scattering should be synonymous to even smaller or zero total scattering, regardless of the nature of the object and of its design. Using analytical theory and an accurate scattering formulation, we clarify the nature of this apparent paradox and the limitations of this anomalous phenomenon in terms of particle size. In this way, we shed some new light on theoretical and experimental papers on the topic, identifying relevant missteps in some of their physical interpretation, and considering the general possibility of verifying these effects. This discussion may also be relevant to some cloaking applications using exotic artificial materials. 765-767 (1983)] theoretically pointed out the interesting possibility of conceiving small magnetodielectric spheres that may provide zero scattering in the forward direction, despite significantly larger scattering in any other direction. Recent experimental and theoretical papers on the topic have further discussed this possibility in more realistic scenarios. Inspecting some of their analyses, it seems indeed possible to conceive nanoparticles characterized by a scattering pattern with a sharp minimum, although not zero, in the forward direction. From a theoretical standpoint, however, it is well known that the total scattered power from any object has to be proportional to a portion of the scattered field in the forward direction, implying that very small or zero forward scattering should be synonymous to even smaller or zero total scattering, regardless of the nature of the object and of its design. Using analytical theory and an accurate scattering formulation, we clarify the nature of this apparent paradox and the limitations of this anomalous phenomenon in terms of particle size. In this way, we shed some new light on theoretical and experimental papers on the topic, identifying relevant missteps in some of their physical interpretation, and considering the general possibility of verifying these effects. This discussion may also be relevant to some cloaking applications using exotic artificial materials.

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“…In this case, these scattering coefficients are usually approximated by their first-order Taylor expansion [11][12][13][14][15][16]:…”

Section: Quasi-static Limit and The Zero-forward Scattering Conditionmentioning

confidence: 99%

Section: Quasi-static Limit and The Zero-forward Scattering Conditionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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How does zero forward-scattering in magnetodielectric nanoparticles comply with the optical theorem?

Alù

Engheta

2010

J. Nanophoton

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“…However, achieving such magnetodielectric behaviour has been prevented because of the absence of natural magnetic media at optical frequencies and to the lossy magnetic materials in the microwave regime. Recent reports on the observation of zero-forward scattering by magnetic spheres 13,14 according to Kerker criteria 8 was questioned [15][16][17] . Thus to date there has been no unambiguous experimental evidence.…”

mentioning

confidence: 99%

Magnetic and electric coherence in forward- and back-scattered electromagnetic waves by a single dielectric subwavelength sphere

et al. 2012

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Magnetodielectric small spheres present unusual electromagnetic scattering features, theoretically predicted a few decades ago. However, achieving such behaviour has remained elusive, due to the non-magnetic character of natural optical materials or the difficulty in obtaining low-loss highly permeable magnetic materials in the gigahertz regime. Here we present unambiguous experimental evidence that a single low-loss dielectric subwavelength sphere of moderate refractive index (n ¼ 4 like some semiconductors at near-infrared) radiates fields identical to those from equal amplitude crossed electric and magnetic dipoles, and indistinguishable from those of ideal magnetodielectric spheres. The measured scattering radiation patterns and degree of linear polarization (3-9 GHz/33-100 mm range) show that, by appropriately tuning the a/l ratio, zero-backward ('Huygens' source) or almost zeroforward ('Huygens' reflector) radiated power can be obtained. These Kerker scattering conditions only depend on a/l. Our results open new technological challenges from nanoand micro-photonics to science and engineering of antennas, metamaterials and electromagnetic devices.

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Mathematical Modelling of Mie Scattering for Magnetic Spheres Surrounded by Magnetic Medium

Khatsuriya,

Markana

2023

Advances in Intelligent Systems and Computing

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Experimental Evidence of Zero Forward Scattering by Magnetic Spheres

Cited by 61 publications

References 17 publications

How does zero forward-scattering in magnetodielectric nanoparticles comply with the optical theorem?

How does zero forward-scattering in magnetodielectric nanoparticles comply with the optical theorem?

Magnetic and electric coherence in forward- and back-scattered electromagnetic waves by a single dielectric subwavelength sphere

Mathematical Modelling of Mie Scattering for Magnetic Spheres Surrounded by Magnetic Medium

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