Chiral mirrors

Plum, Eric; Zheludev, Nikolay I.

doi:10.1063/1.4921969

Cited by 193 publications

(184 citation statements)

References 27 publications

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“…This mirror is known as a handedness-preserving mirror (HPM) [24]. Today, there are several experimentally measured HPMs based on metasurfaces [47][48][49]. HPM retains not only the handedness but also the ellipticity magnitude upon reflection, therefore, such a mirror is also referred to as a polarization-preserving anisotropic mirror [50].…”

Section: Introductionmentioning

confidence: 99%

Chiral Optical Tamm States: Temporal Coupled-Mode Theory

et al. 2017

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Abstract:The chiral optical Tamm state (COTS) is a special localized state at the interface of a handedness-preserving mirror and a structurally chiral medium such as a cholesteric liquid crystal or a chiral sculptured thin film. The spectral behavior of COTS, observed as reflection resonances, is described by the temporal coupled-mode theory. Mode coupling is different for two circular light polarizations because COTS has a helical structure replicating that of the cholesteric. The mode coupling for co-handed circularly polarized light exponentially attenuates with the cholesteric layer thickness since the COTS frequency falls into the stop band. Cross-handed circularly polarized light freely goes through the cholesteric layer and can excite COTS when reflected from the handedness-preserving mirror. The coupling in this case is proportional to anisotropy of the cholesteric and theoretically only anisotropy in magnetic permittivity can ultimately cancel this coupling. These two couplings being equal result in a polarization crossover (the Kopp-Genack effect) for which a linear polarization is optimal to excite COTS. The corresponding cholesteric thickness and scattering matrix for COTS are generally described by simple expressions.

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Section: Introductionmentioning

confidence: 99%

Chiral Optical Tamm States: Temporal Coupled-Mode Theory

et al. 2017

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“…As an extension of this work, we recently looked at the reflective effects of chiral metasurfaces [24]. We demonstrated a type of mirror reflecting one circular polarization without changing its handedness, while absorbing the other [25]. The polarization-preserving mirror consists of a planar metasurface and a conventional mirror spaced by a fraction of the wavelength from the metasurface.…”

Section: Earlier Days From Optics To Microwaves and Backmentioning

confidence: 99%

Metamaterials at the University of Southampton and beyond

Zheludev¹

2017

J. Opt.

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At the University of Southampton, research on metamaterials started in 2000 with a paper describing a metallic microstructure, comprising an ensemble of fully metallic 'molecules'. In the years since then, metamaterials have evolved from an approach for designing unusual electromagnetic properties by structuring matter at the sub-wavelength scale to become a universal paradigm for active functional media with optical properties on demand at any given point in time and space. Metamaterials are now recognized as a promising enabling technology and one of the most buoyant and exciting research disciplines at the crossroads between photonics and nanoscience. Many 'made in Southampton' concepts have influenced the global research community, and we are now working in collaboration with our sister research centre in Nanyang Technological University, Singapore. In this article, I provide a historical overview of the metamaterials research field, from early studies to recent developments through the lens of the Southampton group, and discuss promising future directions.

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“…This functionality cannot be realized on the basis of intrinsic 3D chirality, 26 but recently perfect absorbers for circularly polarized waves based on intrinsic 31 and extrinsic…”

Section: -30mentioning

confidence: 99%

Extrinsic chirality: Tunable optically active reflectors and perfect absorbers

Plum

2016

Applied Physics Letters

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Conventional three-dimensionally (3D) chiral media can exhibit optical activity for transmitted waves, but optical activity for reflected waves is negligible. This work shows that mirror asymmetry of the experimental arrangement -extrinsic 3D chirality -leads to giant optical activity for reflected waves with fundamentally different characteristics. It is demonstrated experimentally that extrinsically 3D-chiral illumination of a lossy metasurface backed by a mirror enables tunable circular dichroism and circular birefringence as well as perfect absorption of circularly polarized waves. In contrast, such polarization phenomena vanish for conventional optically active media backed by a mirror.Optical activity, that is rotation of the polarization state of light (circular birefringence) and differential absorption of circularly polarized waves (circular dichroism), is a well-known consequence of transmission through chiral media. It is usually observed in intrinsically 3D-chiral structures, i.e. structures that cannot be superimposed with their mirror image (Fig. 1a). Large polarization changes occur for transmission through 3D-chiral metamaterials, 1-7 and natural media 8 where effects can accumulate over long interaction lengths. In contrast, circular birefringence and dichroism for waves reflected from 3D-chiral solids and liquids are usually negligible. 9-12It is less well-known that optical activity also occurs in achiral structures, if the direction of the wave incident onto the material makes the experimental arrangement different from its mirror image (Fig. 1b). This is known as extrinsic 3D chirality and leads to large circular birefringence and dichroism for both transmitted [13][14][15][16][17] and reflected 18 waves as well as similar phenomena for scattering 19 and second harmonic generation 20 by nanostructures. Extrinsic 3D chirality is present for oblique incidence onto structured interfaces (e.g. planar metamaterials also known as metasurfaces) that lack two-fold rotational symmetry, if the structure does not have a line of mirror symmetry in the plane of incidence. Other forms of extrinsic chirality resulting in directionally asymmetric transmission 21 and different photoluminescence 22 for opposite circular polarizations have also been reported. This letter demonstrates a fundamental difference between optical activity due to intrinsic and extrinsic 3D chirality. Polarization changes due to intrinsic 3D chirality will be reversed if the electromagnetic wave is reflected back through the 3D-chiral medium. In contrast, polarization changes due to extrinsic 3D chirality will not vanish under the same circumstances, providing an opportunity to tune specular optical activity and to realize perfect absorbers for circularly polarized waves. Figure 1c,d illustrates why placing an optically active medium in front of a mirror will lead to vanishing a) Electronic mail: erp@orc.soton.ac.uk; www.nanophotonics.org.uk and enhanced optical activity in case of intrinsic and extrinsic 3D chirality, respectively. A...

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Chiral mirrors

Cited by 193 publications

References 27 publications

Chiral Optical Tamm States: Temporal Coupled-Mode Theory

Chiral Optical Tamm States: Temporal Coupled-Mode Theory

Metamaterials at the University of Southampton and beyond

Extrinsic chirality: Tunable optically active reflectors and perfect absorbers

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