Applications and Potentials of Reciprocal Bianisotropic Metasurfaces

Albooyeh, Mohammad; Asadchy, Viktar; Zeng, Jinwei; Kazemi, Hamidreza; Capolino, Filippo

doi:10.23919/ursi-emts.2019.8931447

Cited by 5 publications

(7 citation statements)

References 14 publications

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“…It is worth mentioning that LP-base responses could be used in determining the origin of the CD of some structures, whether it is chirality or in-plane anisotropy. However, in our case, the structure is reflective (the transmission is almost zero), so we have only the reflection data available, which is not enough to determine the origin of the CD . Nevertheless, it is interesting to observe the results based on LP incidence here, which show the agreement between simulation and experiment and also verifies the fabrication and measurement setup.…”

Section: Resultssupporting

confidence: 53%

“…Here, our structured surface is a reflective structure (transmission is almost zero), so we have only the reflection data, and not the transmission response, to analyze it and infer its properties. It can be shown that determining the origin of CD, that is, whether it is from chirality or from in-plane anisotropy, is not possible from only the amplitude of the reflection data . Therefore, we cannot necessarily attribute the observed CD from our structure to chirality, although our structure is indeed geometrically chiral.…”

mentioning

confidence: 90%

“…It is important to note that, although a structure may be chiral or in-plane anisotropic (by looking at the geometry), its electromagnetic response may or may not carry the signature of chirality or in-plane anisotropy since the scattered signature depends on the kind of chosen excitation. In other words, one should select a proper excitation depending on what geometrical property is investigated . Therefore, if a CD is obtained from a broken symmetry structure, referring to that structure as chiral or anisotropic may be confusing, and more analysis is required to determine the origin of the CD.…”

mentioning

confidence: 99%

“…Therefore, if a CD is obtained from a broken symmetry structure, referring to that structure as chiral or anisotropic may be confusing, and more analysis is required to determine the origin of the CD. A complete and thorough explanation about the origin of CD has been given in ref . Here, our structured surface is a reflective structure (transmission is almost zero), so we have only the reflection data, and not the transmission response, to analyze it and infer its properties.…”

mentioning

confidence: 99%

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Giant Circular Dichroism at Visible Frequencies Enabled by Plasmonic Ramp-Shaped Nanostructures

et al. 2019

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Plasmonic nanostructures with spatial symmetry breaking have a variety of applications, from enhancing the enantioselective detection of chiral molecules to creating photonics devices such as circular polarizers. Compared to their molecular counterparts, engineered nanostructures exhibit orders of magnitude larger circular dichroism (CD) at optical frequencies. Although 3D nanostructures such as nanohelices have been reported with high CD at mid-IR frequencies, such high CDs have not yet been achieved at visible frequencies with decent efficiencies. Here, we propose a planar array of plasmonic ramp-shaped nanostructures with an azimuthally gradient depth that exhibits a giant CD and dissymmetry factor at visible frequencies. The structure is fabricated on a gold-coated glass slide using focused ion beam (FIB) with gradient intensity to induce the required gradient depth, hence, breaking symmetry. Optical experimental characterization in the reflection spectrum shows a CD up to 64% and a dissymmetry factor up to 1.13 at 678 nm, in a good agreement with numerical simulations. We envision our proposed structure together with the suggested fabrication method to inspire the design of novel optical devices such as nanoscale circular polarizers and a host of chiral molecules to improve enantioselectivity in the pharmaceutical industry.

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Section: Resultssupporting

confidence: 53%

mentioning

confidence: 90%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Giant Circular Dichroism at Visible Frequencies Enabled by Plasmonic Ramp-Shaped Nanostructures

et al. 2019

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“…The normal component of the susceptibility tensors χ are often zero or negligible [32] [33], and are discarded in this work, for simplicity. Furthermore, we will simplify to a uniaxial surface with no cross-coupling, so the equations simplify and can be written in the time domain as [34]…”

Section: Space-time Modulated Metasurfaces a Problem Statementmentioning

confidence: 99%

Floquet Analysis of Space-Time Modulated Huygens' Metasurfaces with Lorentz Dispersion

Tiukuvaara,

Smy,

Gupta

2020

Preprint

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A rigorous semi-analytical Floquet analysis is proposed for a zero-thickness space-time modulated Huygens' metasurface to model and determine the strengths of the new harmonic components of the scattered fields. The proposed method is based on Generalized Sheet Transition Conditions (GSTCs) treating a metasurface as a spatial discontinuity. The metasurface is described in terms of Lorentzian electric and magnetic surface susceptibilities, χe and χm, respectively, with parameters (e.g. resonant frequency) that are periodically modulated in both space and time. The unknown scattered fields are expressed in terms of Floquet harmonics, for which the amplitudes can be found by numerically solving a set of linear equations, leading to the total scattered fields. Using existing computational techniques, the method is validated using several examples of pure-space and pure-time modulation with different modulation strengths and pumping frequencies. Finally, two cases of spacetime modulation (standing wave perturbation and a travelling wave perturbation) are presented to demonstrate the breaking of Lorentz reciprocity. The proposed method is simple and versatile and able to determine the steady-state response of a space-time modulated Huygen's metasurface that is excited with an oblique plane wave, or a general incident field such as a Gaussian beam.

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Intrinsic Superchirality in Planar Plasmonic Metasurfaces

Palermo,

Rippa,

Aceti

et al. 2024

Nano Lett.

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Plasmonic metasurfaces with spatial symmetry breaking are crucial materials with significant applications in fields such as polarization-controlled photonic devices and nanophotonic platforms for chiral sensing. In this paper, we introduce planar plasmonic metasurfaces, less than one-tenth of a wavelength thick, featuring nanocavities formed by three equilateral triangles. This configuration creates uniform, thin metasurfaces. Through a combination of experimental measurements and numerical modeling, we demonstrate the inherent superchirality of these plasmonic metasurfaces. We address the challenge of achieving a strong enhancement of optical chirality in the visible spectrum, reaching levels comparable to those of 3D chiral metasurfaces.

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Applications and Potentials of Reciprocal Bianisotropic Metasurfaces

Cited by 5 publications

References 14 publications

Giant Circular Dichroism at Visible Frequencies Enabled by Plasmonic Ramp-Shaped Nanostructures

Giant Circular Dichroism at Visible Frequencies Enabled by Plasmonic Ramp-Shaped Nanostructures

Floquet Analysis of Space-Time Modulated Huygens' Metasurfaces with Lorentz Dispersion

Intrinsic Superchirality in Planar Plasmonic Metasurfaces

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