A new model of geometric chirality for two-dimensional continuous media and planar meta-materials

Potts, A.; Bagnall, Darren M.; Zheludev, Nikolay I.

doi:10.1088/1464-4258/6/2/007

Cited by 36 publications

(22 citation statements)

References 15 publications

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“…1,2 However, we will now demonstrate that similar effects are observable for visible light diffracted from patterned polymer films, suggesting that other mechanisms ͑such as electro-magnetic displacement currents or Fabry-Perot interference effects͒ may also play a significant role. More importantly, these results suggest that most patterned thin films that exhibit twodimensional chirality 5 could be capable of exhibiting polarization sensitive effects, irrespective of the physical properties of the medium in which the chiral pattern is formed.…”

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confidence: 87%

Intensity modulation and polarization rotation of visible light by dielectric planar chiral metamaterials

Zhang

Potts

Papakostas

et al. 2005

Applied Physics Letters

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We have demonstrated how dielectric planar chiral surfaces can both modulate the intensity and change the polarization state of visible light diffracted from patterned surfaces. These effects are shown to be dependent on the sense of chirality of the surface and the input polarization state of the light. Individual diffracted beams can show variations of over 30% in their intensities for different input polarization states while opposite enantiomeric structures can exhibit differences of over 50%. The size of these effects could make these surfaces particularly promising candidates for the development of solid-state polarization-state detectors. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1944211͔Metallic planar chiral metamaterials with characteristic length-scales of a few microns have attracted significant interest recently in light of their novel and intriguing polarization properties. 1,2 Most notable of these is their ability to rotate and elliptize the polarization state of light. These effects were first observed for visible light diffracted in reflection from samples consisting of regular arrays of gammadion-shaped holes etched into thin metallic films 3 and were similar in form to effects that had been predicted for somewhat larger structures designed to operate in the microwave regime. 4 The underlying mechanism for these effects has previously been ascribed, at least in part, to the generation of induced currents or surface-plasmon-polaritons ͑SPP͒ in the walls of the metallic gammadions. 1,2 However, we will now demonstrate that similar effects are observable for visible light diffracted from patterned polymer films, suggesting that other mechanisms ͑such as electro-magnetic displacement currents or Fabry-Perot interference effects͒ may also play a significant role. More importantly, these results suggest that most patterned thin films that exhibit twodimensional chirality 5 could be capable of exhibiting polarization sensitive effects, irrespective of the physical properties of the medium in which the chiral pattern is formed.The global significance of these results is that they allude to the possibility of the creation of truly nonreciprocal optical structures from materials that are inherently nonmagnetic. Such effects have been predicted theoretically for a number of idealized physical structures subject to various preliminary assumptions and approximations, 4,6,7 but if they could be demonstrated experimentally for real structures they would undoubtedly prove crucial for the development of entirely new optical devices such as polarization sensitive detectors, manipulators, and other optical elements. Unfortunately, our attempts to realize such a device have so far failed to show any chirality-induced polarization change in the zero-order beam in either reflection or transmission when the sample is illuminated at either normal incidence or glazing incidence. However, other workers studying sub-wavelength structures ͑in which the average separation of the chiral elements, ⌳, is less tha...

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confidence: 87%

Intensity modulation and polarization rotation of visible light by dielectric planar chiral metamaterials

Zhang

Potts

Papakostas

et al. 2005

Applied Physics Letters

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“…The chiral 'fish-scale' is a 2-dimensional continuous pattern of tilted meanders existing in two enantiomeric (mirror) forms interconverted by reflection across a line in the plane of the structure (see Fig.2). On the basis of both intuitive perception and strict mathematical definition [9], the lefttilted fish-scale A shows an overall anti-clockwise twist, while the right-tilted fish-scale B twists clockwise. An axial 'twist' vector W, governed by the cork-screw law, may be associated with each of the enantiomers.…”

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confidence: 99%

Asymmetric Propagation of Electromagnetic Waves through a Planar Chiral Structure

et al. 2006

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We report the first experiential observation and theoretical analysis of the new phenomenon of planar chiral circular conversion dichroism, which in some aspects resembles the Faraday effect in magnetized media, but does not require the presence of a magnetic field for its observation. It results from the interaction of an electromagnetic wave with a planar chiral structure patterned on the sub-wavelength scale, and manifests itself in asymmetric transmission of circularly polarized waves in the opposite directions through the structure and elliptically polarized eigenstates. The new effect is radically different from conventional gyrotropy of three-dimensional chiral media.Since Hetch and Barron [1] and Arnaut and Davis [2] first introduced planar chiral structures to electromagnetic research they have become the subject of intense theoretical [3,4] and experimental investigations with respect to the polarization properties of scattered fields [5,6,7]. It was understood by many that planar chirality is essentially different in symmetry from threedimensional chirality. Whereas in three-dimensional chiral structures the sense of perceived rotation remains unchanged for opposing directions of observation (think, for example, of a helix observed along its axis), planar chiral structures possess a sense of twist that is reversed when they are observed from opposite sides of the plane to which the structure belongs. Consequently, if planar chiral structures were to exhibit a polarization effect (due to this twist) for light incident normal to the plane, the sense of the effect would be reversed for light propagating in opposite directions. Such behavior has never been observed before, but if proven would be of profound benefit to the development of a new class of microwave and optical devices.In this paper we report such a polarization sensitive effect. It is a previously unknown fundamental phenomenon of electromagnetism that asymmetric materials can generate behaviors that in some ways resemble the famous non-reciprocity of the Faraday effect, which emerges when a wave propagates through a magnetized medium. However, the phenomenon reported here does not require the presence of a magnetic field and results from an electromagnetic wave's transmission through a chiral planar structure patterned on the sub-wavelength scale. Both in the Faraday effect and in that produced by planar chirality, the transmission and retardation of a circularly polarized wave are different in opposite directions. In both cases the polarization eigenstates, i.e. polarization states conserved on propagation, are elliptical (circular).There are also essential differences between the two phenomena. The asymmetry of the Faraday effect with respect to propagation in opposite directions applies to the transmission and retardation of the incident circularly polarized wave itself. The planar chirality effect leads to the (partial) conversion of the incident wave into one of opposite handedness, and it is the efficiency of this conversion that is as...

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“…Previous studies of planar chiral geometries have focused on straight or curved open-ended wire-type geometries, such as generalized swastikas (gammadions) [7], [10]- [17], [21], planar chiral hooks (L-or J-shaped wires, or indeed most letters of the alphabet) [1,5,16], scalene triangles [22,23], spirals [20,24], etc. These works follow a "bottomup" approach, in which a planar chiral geometry is synthesized via assembly of concatenated 1-D wire segments.…”

Section: Motivationmentioning

confidence: 99%

“…As emphasized in [23], chirality is a purely geometric notion. While it manifests itself through symmetries and dissymmetries of the azimuthal current distribution, this does not necessarily affect electromagnetic (EM) and magnetoelectric (ME) polarizabilities through pseudo-scalarity of their elements.…”

Section: Electromagnetic Signature Of Planar Chiralitymentioning

confidence: 99%

Planar chirality of plasmonic multi-split rings

Arnaut¹

2009

J. Opt. A: Pure Appl. Opt.

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Abstract. We develop an analytical framework for the analysis of planar chiral multi-split rings, based on a Fourier series expansion of the induced current. The number, width, and location of each split (gap) is arbitrary. Provision is made for the possibility of inserting lumped active or passive impedance loads in the gaps. The model demonstrates the hallmark of planar chirality and its consequent magneto-electric coupling as a function of the parameters of the splits and impedance loads. It is demonstrated that impedance loads sequenced in a clockwise or anti-clockwise fashion allow for generation of dissymetric current distributions in the plane, like for geometric (structural) chirality.We also determine the effect of planar chirality on the relevant dyadic polarizability components of a split ring.Reflection and transmission coefficient characteristics of regular arrays of such rings are determined with the aid of the periodic method of moments. Phase-coherent detection of the sense of handedness and incoherent detection of planar chirality per se by measurement of the field intensity are shown to be possible, in both the reflection and transmission characteristics. These results are relevant to both coherent and incoherent detection at optical and suboptical wavelengths.

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A new model of geometric chirality for two-dimensional continuous media and planar meta-materials

Cited by 36 publications

References 15 publications

Intensity modulation and polarization rotation of visible light by dielectric planar chiral metamaterials

Intensity modulation and polarization rotation of visible light by dielectric planar chiral metamaterials

Asymmetric Propagation of Electromagnetic Waves through a Planar Chiral Structure

Planar chirality of plasmonic multi-split rings

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