Giant Optical Activity in Quasi-Two-Dimensional Planar Nanostructures

Kuwata‐Gonokami, Makoto; Saito, Nobuyoshi; Ino, Y.; Kauranen, Martti; Jefimovs, Konstantins; Vallius, Tuomas; Turunen, Jari; Svirko, Yuri

doi:10.1103/physrevlett.95.227401

Cited by 559 publications

(503 citation statements)

References 18 publications

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“…Lossless planar chiral metamaterial shall not display asymmetric transmission for a circularly polarized wave. As we already mentioned above, this asymmetric effect is also forbidden in any planar structure containing a 4-fold axis of rotation and is therefore irrelevant to the recent observation of the polarization rotation in four-fold gammadion arrays [12].…”

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confidence: 98%

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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Asymmetric Propagation of Electromagnetic Waves through a Planar Chiral Structure

et al. 2006

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“…In part inspired by biological species that are well equipped with broadband, conformal circular polarization sensors 12 , optical activity and circular dichroism have been shown in either planar [13][14][15][16][17][18] or three-dimensional metamaterials 3,19,20 . Planar structures generally exhibit much weaker circular dichroism compared with 3D geometries, because an infinitesimally thin device is inherently achiral, and excitation at oblique incidence or some form of nonreciprocal response is required to distinguish between LCP and RCP transmissivity 21 .…”

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confidence: 99%

“…Planar structures generally exhibit much weaker circular dichroism compared with 3D geometries, because an infinitesimally thin device is inherently achiral, and excitation at oblique incidence or some form of nonreciprocal response is required to distinguish between LCP and RCP transmissivity 21 . In this context, the concept of extrinsic chirality has been recently put forward, showing that, by pairing two closely spaced planarized inclusions with some form of 3D chirality, may produce a narrow-band chiral response near their resonance [13][14][15][16][17][18] .…”

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Twisted optical metamaterials for planarized ultrathin broadband circular polarizers

2012

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optical metamaterials are usually based on planarized, complex-shaped, resonant nanoinclusions. Three-dimensional geometries may provide a wider set of functionalities, including broadband chirality to manipulate circular polarization at the nanoscale, but their fabrication becomes challenging as their dimensions get smaller. Here we introduce a new paradigm for the realization of optical metamaterials, showing that three-dimensional effects may be obtained without complicated inclusions, but instead by tailoring the relative orientation within the lattice. We apply this concept to realize planarized, broadband bianisotropic metamaterials as stacked nanorod arrays with a tailored rotational twist. Because of the coupling among closely spaced twisted plasmonic metasurfaces, metamaterials realized with conventional lithography may effectively operate as three-dimensional helical structures with broadband bianisotropic optical response. The proposed concept is also shown to relax alignment requirements common in three-dimensional metamaterial designs. The realized sample constitutes an ultrathin, broadband circular polarizer that may be directly integrated within nanophotonic systems.

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“…Recently, chiral metamaterials have attracted great interest because of the possibility to achieve negative refraction by means of chirality 6 or to artificially reproduce and enhance the weak chiro-optical effects present in natural chiral molecules (enantiomers). Indeed, quasi-free electrons in collective plasmon oscillations have been shown to overcome some natural limitations in two-dimensional chiral metamaterial structures [7][8][9] . However, these structures need oblique incidence of light to discriminate polarizations with opposite handedness and also exhibit weak dichroic selection.…”

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Triple-helical nanowires by tomographic rotatory growth for chiral photonics

et al. 2015

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Three dimensional helical chiral metamaterials resulted in effective manipulation of circularly polarized light in the visible infrared for advanced nanophotonics. Their potentialities are severely limited by the lack of full rotational symmetry preventing broadband operation, high signal-to-noise ratio and inducing high optical activity sensitivity to structure orientation. Complex intertwined three dimensional structures such as multiple-helical nanowires could overcome these limitations, allowing the achievement of several chiro-optical effects combining chirality and isotropy. Here we report three dimensional triple-helical nanowires, engineered by the innovative tomographic rotatory growth, on the basis of focused ion beam-induced deposition. These three dimensional nanostructures show up to 37% of circular dichroism in a broad range (500-1,000 nm), with a high signal-to-noise ratio (up to 24 dB). Optical activity of up to 8°only due to the circular birefringence is also shown, tracing the way towards chiral photonic devices that can be integrated in optical nanocircuits to modulate the visible light polarization.

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Giant Optical Activity in Quasi-Two-Dimensional Planar Nanostructures

Cited by 559 publications

References 18 publications

Asymmetric Propagation of Electromagnetic Waves through a Planar Chiral Structure

Asymmetric Propagation of Electromagnetic Waves through a Planar Chiral Structure

Twisted optical metamaterials for planarized ultrathin broadband circular polarizers

Triple-helical nanowires by tomographic rotatory growth for chiral photonics

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