Enhanced Near-Field Chirality in Periodic Arrays of Si Nanowires for Chiral Sensing

Petronijevic, Emilija; Sibilia, C.

doi:10.3390/molecules24050853

Cited by 12 publications

(10 citation statements)

References 36 publications

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“…Furthermore, the enhanced enantioselectivity due to the enhanced near chiral fields was theoretically proposed in [25,26] and observed in the interaction with plasmonic substrates [27,28]. For this purpose, we previously proposed single hybrid GaAs-Au nanowires [29,30], periodic arrays of high refractive index nanowires [31], and arrays of Al nanopyramids [32]. Moreover, chiroptical responses were studied in simple 1D metal grooves [33] and nanohole arrays [34].…”

Section: Introductionmentioning

confidence: 99%

Circular Dichroism in Low-Cost Plasmonics: 2D Arrays of Nanoholes in Silver

et al. 2020

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Arrays of nanoholes in metal are important plasmonic devices, proposed for applications spanning from biosensing to communications. In this work, we show that in such arrays the symmetry can be broken by means of the elliptical shape of the nanoholes, combined with the in-plane tilt of the ellipse axes away from the array symmetry lines. The array then differently interacts with circular polarizations of opposite handedness at normal incidence, i.e., it becomes intrinsically chiral. The measure of this difference is called circular dichroism (CD). The nanosphere lithography combined with tilted silver evaporation was employed as a low-cost fabrication technique. In this paper, we demonstrate intrinsic chirality and CD by measuring the extinction in the near-infrared range. We further employ numerical analysis to visualize the circular polarization coupling with the nanostructure. We find a good agreement between simulations and the experiment, meaning that the optimization can be used to further increase CD.

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Section: Introductionmentioning

confidence: 99%

Circular Dichroism in Low-Cost Plasmonics: 2D Arrays of Nanoholes in Silver

et al. 2020

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“…We further verified, using photoacoustic spectroscopy, that when such GaAs NWs were partially covered in gold they exhibited strong extrinsic chirality due to the breaking of the symmetry induced by the asymmetric metal coating [11,12]. We also numerically investigated nearfield chiral effects in high-refractive-index nanowires with [22] and without [23] an asymmetric plasmonic layer.…”

Section: Methodsmentioning

confidence: 66%

Circular Dichroism in the Second Harmonic Field Evidenced by Asymmetric Au Coated GaAs Nanowires

et al. 2020

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Optical circular dichroism (CD) is an important phenomenon in nanophotonics, that addresses top level applications such as circular polarized photon generation in optics, enantiomeric recognition in biophotonics and so on. Chiral nanostructures can lead to high CD, but the fabrication process usually requires a large effort, and extrinsic chiral samples can be produced by simpler techniques. Glancing angle deposition of gold on GaAs nanowires can (NWs) induces a symmetry breaking that leads to an optical CD response that mimics chiral behavior. The GaAs NWs have been fabricated by a self-catalyzed, bottom-up approach, leading to large surfaces and high-quality samples at a relatively low cost. Here, we investigate the second harmonic generation circular dichroism (SHG-CD) signal on GaAs nanowires partially covered with Au. SHG is a nonlinear process of even order, and thus extremely sensitive to symmetry breaking. Therefore, the visibility of the signal is very high when the fabricated samples present resonances at first and second harmonic frequencies (i.e., 800 and 400 nm, in our case).

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“…[52,53] Hence, besides suggesting the possibility of using photonic integrated platforms for chiral applications, these findings may lay the groundwork for a greater variety of chiroptical effects. [54,55]…”

Section: Introductionmentioning

confidence: 99%

Toward Chiral Sensing and Spectroscopy Enabled by All‐Dielectric Integrated Photonic Waveguides

Vázquez‐Lozano

Martı́nez

2020

Laser & Photonics Reviews

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Chiral spectroscopy is a powerful technique enabling to identify optically the chirality of matter. So far, most experiments to check the chirality of matter or nanostructures have been performed through arrangements wherein both the optical excitation and detection are realized via circularly polarized light propagating in free space. However, for the sake of miniaturization, it would be desirable to perform chiral spectroscopy in photonic integrated platforms, with the additional benefit of massive parallel detection, low‐cost production, repeatability, and portability. Here it is shown that all‐dielectric photonic waveguides can support chiral modes under proper combination of fundamental eigenmodes. Two mainstream configurations are investigated: a dielectric wire with square cross section and a slotted waveguide. Three different scenarios in which such waveguides could be used for chiral detection are numerically analyzed: waveguides as near‐field probes, evanescent‐induced chiral fields, and chiroptical interaction in void slots. In all the cases, a metallic nanohelix is considered as a chiral probe, though all the approaches can be extended to other kinds of chiral nanostructures as well as matter. These results establish that chiral applications such as sensing and spectroscopy could be realized in standard integrated optics, in particular, with silicon‐based technology.

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Enhanced Near-Field Chirality in Periodic Arrays of Si Nanowires for Chiral Sensing

Cited by 12 publications

References 36 publications

Circular Dichroism in Low-Cost Plasmonics: 2D Arrays of Nanoholes in Silver

Circular Dichroism in Low-Cost Plasmonics: 2D Arrays of Nanoholes in Silver

Circular Dichroism in the Second Harmonic Field Evidenced by Asymmetric Au Coated GaAs Nanowires

Toward Chiral Sensing and Spectroscopy Enabled by All‐Dielectric Integrated Photonic Waveguides

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