Ultrathin Suspended Chiral Metasurfaces for Enantiodiscrimination

Cen, Mengjia; Wang, Jiawei; Liu, Jianxun; He, Huilin; Li, Ké; Cai, Wenfeng; Cao, Tun; Liu, Yan Jun

doi:10.1002/adma.202203956

Cited by 25 publications

(23 citation statements)

References 72 publications

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“…It can be clearly seen from Figure S6 that the core–shell UCNPs are distributed uniformly over the film, and there is no obvious CD signal in the visible-NIR regime, which further confirms that the CD response is mainly attributed to the suspended bilayer chiral metasurface. As known, electromagnetic fields with intense optical chirality can be formed in the near field of plasmonic chiral nanostructures. ,, Subsequently, we have used the finite-difference time-domain (FDTD) method to simulate the localized optical chirality (indicating the cross-coupling intensity between the magnetic and electric fields) distribution at the XY ( Z = 0 and 26 nm) plane with LCP and RCP incident light (at the CD peak of 830 nm). Figures b and S7 exhibit that the optical chirality is mainly localized in the close vicinity of the Au nanostructures, hence presenting a remarkable asymmetric distribution for LCP and RCP incident light at the wavelength of 830 nm.…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, asymmetric transmission, namely, the difference in optical response between backward (i.e., from bottom to top) and forward (i.e., from top to bottom) incidence, is an extraordinary chiroptical effect in the planar chiral structures. − Thus, we have also experimentally measured the asymmetric transmission of the chiral metasurface via backward and forward incidence. In Figure S5c and d, the CD curves from backward and forward incidence show a difference in peak position and intensity, which is ascribed to the asymmetric transmission of LCP and RCP through the bilayer chiral metasurface . As a control experiment, the core–shell UCNPs were also spin-coated on a blank Si 3 N 4 film to characterize the CD properties.…”

Section: Resultsmentioning

confidence: 99%

“…The structural parameters of gold chiral nanoblocks used for simulation were retrieved from the SEM images. The wavelength-dependent refractive indices of Au and Si 3 N 4 were based on the data from the Johnson and Christy model and our previous work, 44 respectively. In addition, the reflective index of the surrounding medium was set to 1 for air.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…In Figure S5c and d, the CD curves from backward and forward incidence show a difference in peak position and intensity, which is ascribed to the asymmetric transmission of LCP and RCP through the bilayer chiral metasurface. 44 As a control experiment, the core−shell UCNPs were also spin-coated on a blank Si 3 N 4 film to characterize the CD properties. It can be clearly seen from Figure S6 that the core−shell UCNPs are distributed uniformly over the film, and there is no obvious CD signal in the visible-NIR regime, which further confirms that the CD response is mainly attributed to the suspended bilayer chiral metasurface.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Fabrication of the Plasmonic Chiral Metasurface. The gold chiral metasufaces were fabricated on a suspended silicon nitride (Si 3 N 4 ) membrane as reported in our previous work 44 via electronbeam lithography (EBL) followed by an evaporation and lift-off process. A commercial suspended Si 3 N 4 membrane with a thickness of 50 nm (CleanSiN, China) was selected as the substrate, treated with UV ozone, further ultrasonically cleaned with propanol, isopropanol, and ethanol, respectively, and finally dried for use.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Plasmonic Chiral Metasurface-Induced Upconverted Circularly Polarized Luminescence from Achiral Upconversion Nanoparticles

Cen

Wang

et al. 2022

ACS Appl. Mater. Interfaces

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Chirality induction, transfer, and manipulation have aroused great interest in achiral nanomaterials. Here, we demonstrate strong upconverted circularly polarized luminescence from achiral core–shell upconversion nanoparticles (UCNPs) via a plasmonic chiral metasurface-induced optical chirality transfer. The Yb3+-sensitized core–shell UCNPs with good dispersity exhibit intense upconversion luminescence of Tm3+ and Nd3+ through the energy transfer process. By spin-coating the core–shell UCNPs on this chiral metasurface, strong enhancement and circular polarization modulation of upconversion luminescence can be achieved due to resonant coupling between surface plasmons and upconversion nanoparticles. In the UCNPs-on-metasurface composite, a significant upconversion luminescence enhancement can be achieved with a maximum enhancement factor of 32.63 at 878 nm and an overall enhancement factor of 11.61. The luminescence dissymmetry factor of the induced upconverted circularly polarized luminescence can reach 0.95 at the emission wavelength of 895 nm. The UCNPs-on-metasurface composite yields efficient modulation for the emission intensity and polarization of UCNPs, paving new pathways to many potential applications in imaging, sensing, and anticounterfeiting fields.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 3 more Smart Citations

Plasmonic Chiral Metasurface-Induced Upconverted Circularly Polarized Luminescence from Achiral Upconversion Nanoparticles

Cen

Wang

et al. 2022

ACS Appl. Mater. Interfaces

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Near‐Field Coupling Induced Less Chiral Responses in Chiral Metamaterials for Surface‐Enhanced Vibrational Circular Dichroism

Xu,

Ren,

Zhou

et al. 2023

Adv Funct Materials

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Chiral metamaterials play vital roles in manipulating the circular polarization of electromagnetic waves. Although planar chiral metamaterials are believed to have no true/intrinsic chirality, the design of structural anisotropy can still create enormous circular dichroism, while the mechanism is fully explored. Here, for the first time, it is observed that strong near‐field coupling induces less chiral response in chiral metamaterials. Selective exposure methods to manipulate the near‐field coupling strength, and experimentally validate the circular dichroism difference from tailored near‐field coupling effect are leveraged, which provides strong evidence for the assumption and can be utilized for the structural design framework. Besides, using the enhanced near‐field (over 750‐fold), surface‐enhanced vibrational circular dichroism (SEVCD) for glucose enantiomers, which shows a larger‐than‐one normalized sensitivity compared with metamaterials with chiral response is demonstrated. Furthermore, The potential of SEVCD by detecting a broadband signal using arrayed metamaterials is explored. These findings pave the way toward chiroptical nanophotonic designs for potential biomedical and healthcare applications.

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Recent Advances in Ultrathin Chiral Metasurfaces by Twisted Stacking

et al. 2022

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chiral plasmonic nanoparticles and their self-assembled structures as colloidal suspensions. [6][7][8][9] Recently, beyond noble metal plasmonics, solid-state layered nanomaterials that are rotationally aligned with a defined twist angle are becoming increasingly investigated (Figure 1). Among these are twisted 2D van der Waals (vdW) materials, [10][11][12] twisted single-crystal slabs, [13,14] twisted aligned nanowire thin films, [15][16][17][18] and twisted metasurfaces with periodic subunits [19][20][21] (Figure 2). These chiral stacked materials possessing geometric handedness and optical chirality can be seen as truncated and minimalistic versions of supramolecular liquid crystals in the chiral nematic phase or of 3D chiral photonic crystals. [22][23][24] Compared to their bulk or multiple-layer counterparts, the fabrication becomes greatly simplified for bilayer or few-layer chiral metamaterials, enabling precise control over the interlayer twist angle to manipulate lightmatter interactions. Ultrathin chiral metamaterials and metasurfaces with tunable optical and chiroptical responses are thus an active field for study.Twisting achiral layered nanostructures in parallel planes enables engineering of the extrinsic chirality and related optical performance. Specifically, the twist angle from counterclockwise rotation of an upper layer with respect to the beneath one is defined to be positive, θ > 0°, leading to a left-handed stacking geometry. [10,18] Accordingly, negative twist angle from clockwise rotation gives rise to the right-handed counterpart. Accurate control over the interlayer rotation angle offers flexible manipulation of properties, especially optical activity, of twisted layered systems of a wide variety of monolayer constituents and dimensions. A well-studied system is twisted bilayer graphene (TBG), catalyzing the research on twisted stacked nanostructures over the past few years, especially as many intriguing properties of magic-angle graphene are uncovered. [28][29][30] The twist angle dependencies of phonon dispersion, [31] optical absorption and reflection, [32,33] circular dichroism (CD) and birefringence, [10,34] second harmonic generation (SHG), [35] and photoresponse [36,37] of TBG have been extensively explored in the past few years. Similar realizations have been reported for twisted nanostructures of other 2D materials such as transition metal dichalcogenides, [38,39] graphitic carbon nitride, [40] and hexagonal boron nitride (hBN), [41] as well as non-2D systems like polymeric thin films or patterned plasmonic nanohole arrays. [42,43] Therefore, there exists fertile ground for chiral metasurface design Artificial chiral nanostructures have been subjected to extensive research for their unique chiroptical activities. Planarized chiral films of ultrathin thicknesses are in particular demand for easy on-chip integration and improved energy efficiency as polarization-sensitive metadevices. Recently, controlled twisted stacking of two or more layers of nanomaterials, such as 2D van der ...

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Ultrathin Suspended Chiral Metasurfaces for Enantiodiscrimination

Cited by 25 publications

References 72 publications

Plasmonic Chiral Metasurface-Induced Upconverted Circularly Polarized Luminescence from Achiral Upconversion Nanoparticles

Plasmonic Chiral Metasurface-Induced Upconverted Circularly Polarized Luminescence from Achiral Upconversion Nanoparticles

Near‐Field Coupling Induced Less Chiral Responses in Chiral Metamaterials for Surface‐Enhanced Vibrational Circular Dichroism

Recent Advances in Ultrathin Chiral Metasurfaces by Twisted Stacking

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