Damping of the dipole vortex

Li, Xin; Pierce, Donna M.; Arnoldus, Henk F.

doi:10.1364/josaa.28.000778

Cited by 8 publications

(12 citation statements)

References 18 publications

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“…In contrary to the aforementioned bulk devices, the metamaterials (metasurfaces, frequency selective sur- * andra@fotonik.dtu.dk faces) based solutions can be extremely compact, for example, a single thin layer can be enough to get the required polarization state without external magnetic field. Several metamaterials-based polarization conversion devices have already been proposed, which can be tentatively grouped by the operational principle and configuration: birefringent polarizers [7,8], transmission [9][10][11][12][13][14][15][16] and reflection [17][18][19][20][21] polarizers based on resonant particles or slits and chiral metamaterials [22][23][24][25][26][27]. Some of the proposed devices have drawbacks, for example, being based on resonant inclusions, apertures or meta-atoms they usually exhibit a narrow bandwidth or convert a linear polarization into the specific circular one.…”

Section: Introductionmentioning

confidence: 99%

Metamaterial polarization converter analysis: limits of performance

et al. 2013

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In this paper we analyze the theoretical limits of a metamaterial converter that allows for linear-toelliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50%, while the realistic reflection configuration can give the conversion efficiency up to 90%. We show that a double layer transmission converter and a single layer with a ground plane can have 100% polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design for virtually any frequency range of the electromagnetic waves.

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Section: Introductionmentioning

confidence: 99%

Metamaterial polarization converter analysis: limits of performance

et al. 2013

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“…Even though the imaginary part of ε r is very small for the illustration in Figure 7, the effect is dramatic. The rotation of the field lines near the source leads to a displacement of the dipole image in the far field, as in Figure 5 [14]. Just as for the dipole in free space, this provides a possible method for experimental observation of this phenomenon.…”

Section: Rotating Dipole In a Mediummentioning

confidence: 92%

Propagation of Electric Dipole Radiation through a Medium

Arnoldus

2012

ISRN Optics

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When electromagnetic energy propagates through a material medium, the paths of energy flow may be altered, as compared to propagation in free space. We consider radiation emitted by an electric dipole, embedded in a medium with permittivity ε r and permeability μ r . For a linear dipole in free space, the field lines of energy flow are straight, but when the imaginary part of ε r is finite, the field lines in the material become curves in the near field of the dipole. Therefore, the energy flow is redistributed due to the damping in the material. For a circular dipole in free space, the field lines of energy flow wind around the axis perpendicular to the plane of rotation of the dipole moment. When ε r has an imaginary part, this flow pattern is altered drastically. Furthermore, when the real part of ε r is negative, the direction of rotation of the flow lines reverses. In that case, the energy in the field rotates opposite to the direction of rotation of the dipole moment. It is indicated that in metamaterials with a negative index of refraction this may lead to an observable effect in the far field.

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“…It is interesting to notice that the material parameters in the expressions above only appear through μ r and n. There is no explicit dependence on ε r . Equation 14in [3] gives the expression for σq for the case of an embedded electric dipole. The terms in braces are identical, with ε r and μ r switched.…”

Section: Poynting Vectormentioning

confidence: 99%

Propagation of magnetic dipole radiation through a medium

Arnoldus

2016

J. Opt. Soc. Am. A

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An oscillating magnetic dipole moment emits radiation. We assume that the dipole is embedded in a medium with relative permittivity ϵ and relative permeability μ, and we have studied the effects of the surrounding material on the flow lines of the emitted energy. For a linear dipole moment in free space the flow lines of energy are straight lines, coming out of the dipole. When located in a medium, these field lines curve toward the dipole axis, due to the imaginary part of μ. Some field lines end on the dipole axis, giving a nonradiating contribution to the energy flow. For a rotating dipole moment in free space, each field line of energy flow lies on a cone around the axis perpendicular to the plane of rotation of the dipole moment. The field line pattern is an optical vortex. When embedded in a material, the cone shape of the vortex becomes a funnel shape, and the windings are much less dense than for the pattern in free space. This is again due to the imaginary part of μ. When the real part of μ is negative, the field lines of the vortex swirl around the dipole axis opposite to the rotation direction of the dipole moment. For a near-single-negative medium, the spatial extent of the vortex becomes huge. We compare the results for the magnetic dipole to the case of an embedded electric dipole.

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Damping of the dipole vortex

Cited by 8 publications

References 18 publications

Metamaterial polarization converter analysis: limits of performance

Metamaterial polarization converter analysis: limits of performance

Propagation of Electric Dipole Radiation through a Medium

Propagation of magnetic dipole radiation through a medium

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