Enhanced circular dichroism of plasmonic chiral system due to indirect coupling of two unaligned nanorods with metal film

Li, Ying; Bai, Yu; Zhang, Ziyan; Abudukelimu, Abuduwaili; Ren, Yaqi; IKRAM, MUHAMMAD; Li, Qi; Zhang, Zhongyue

doi:10.1364/ao.432156

Cited by 5 publications

(2 citation statements)

References 38 publications

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“…Hence, the spectral versatility factor of our proposed L-shaped metamaterial platform is computed to be χ ≈ 2.17. To the best of our knowledge, this value is one of the highest spectral versatility factors ever measured compared with other experimental works that report tunable chiroptical activity from nanostructures in terms of either CD or 21 – 24 , 26 , 30 , 46 , 47 (see the relevant comparison in Supplementary Material Table S1 ). Note that a further increase in the total thickness of the GLAD fabricated metamaterials will lead to even higher χ values; this will be the subject of our future work.…”

Section: Resultsmentioning

confidence: 52%

Controlling the broadband enhanced light chirality with L-shaped dielectric metamaterials

Kilic,

Hilfiker,

Wimer

et al. 2024

Nat Commun

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The inherently weak chiroptical responses of natural materials limit their usage for controlling and enhancing chiral light-matter interactions. Recently, several nanostructures with subwavelength scale dimensions were demonstrated, mainly due to the advent of nanofabrication technologies, as a potential alternative to efficiently enhance chirality. However, the intrinsic lossy nature of metals and the inherent narrowband response of dielectric planar thin films or metasurface structures pose severe limitations toward the practical realization of broadband and tailorable chiral systems. Here, we tackle these problems by designing all-dielectric silicon-based L-shaped optical metamaterials based on tilted nanopillars that exhibit broadband and enhanced chiroptical response in transmission operation. We use an emerging bottom-up fabrication approach, named glancing angle deposition, to assemble these dielectric metamaterials on a wafer scale. The reported strong chirality and optical anisotropic properties are controllable in terms of both amplitude and operating frequency by simply varying the shape and dimensions of the nanopillars. The presented nanostructures can be used in a plethora of emerging nanophotonic applications, such as chiral sensors, polarization filters, and spin-locked nanowaveguides.

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Section: Resultsmentioning

confidence: 52%

Controlling the broadband enhanced light chirality with L-shaped dielectric metamaterials

Kilic,

Hilfiker,

Wimer

et al. 2024

Nat Commun

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show abstract

“…The structure of chiral plasmonic metamaterial is shown in figures 1(a)-(d): the chiral plasmonic metamaterial structure has a three-layer metal-insulator-metal structure, with the top layer consisting of a lightning-like resonator, the middle layer of silica, and both the bottom and top metal layers of gold. In addition, metal-insulator-metal structures with periodic ordered patterns offer rich optical responses and CD effects from the coupling between the localized plasmon of nanoparticles and the surface plasmon mode sustained by the underlying metallic layer [28]. Figure 1(e) shows the shape of the CD spectral line.…”

Section: Chiral Plasmonic Metamaterials Structurementioning

confidence: 99%

Design of chiral plasmonic metamaterials based on interpretable deep learning

Xie,

Gu,

Guo

2023

J. Phys. D: Appl. Phys.

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Chiral plasmonic metamaterials can amplify chiral signals, resulting in circular dichroism (CD) responses that are several orders of magnitude far beyond those of nature. However, the design process of chiral plasmonic metamaterials based on conventional methods is time-consuming. In recent years, the combination of deep learning (DL) and nanophotonics have accelerated the design of nanophotonic devices. Here, we construct the fully connected neural network (FC-NN) model for the forward prediction and inverse design of chiral plasmonic metamaterials structures and introduce the permutation importance approach to optimize the model and increase its interpretability. Our experimental results show that using the peak magnitude of CD and the corresponding wavelength instead of the entire spectrum as the output in the forward prediction improves the accuracy of the peak magnitude of CD prediction, avoids the introduction of auxiliary networks, and simplifies the network structure; The permutation importance analysis shows that the gold length of the resonator is the most critical structural parameter affecting the CD response. In the inverse design, the permutation importance method helps us to make feature selections for the input of the network. By reducing 251 inputs (the whole CD spectrum) to 4 inputs (the peak magnitude of CD and the corresponding wavelength), the network can still maintain a good prediction performance and decrease the training time of the network. Our proposed method can be extended not only to other DL models to study the CD response of chiral metamaterials but also to other areas where DL is combined with metamaterials to accelerate the system optimization and design process of nanophotonic devices.

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Enhanced chirality induced in a composite structure consisting of α-MoO₃ film and a silver metasurface

Yang

Huang²,

et al. 2023

Appl. Opt.

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Chiral structures have been widely used in many fields, such as biosensing and analytical chemistry. In this paper, the chiral response of a composite structure consisting of α-MoO3 film and a silver (Ag) metasurface is studied. First, the effect of the thickness of α-MoO3 film on the circular dichroism (CD) is discussed, and it is found that CD can reach 0.93 at a wavelength of 9.6 µm when the thickness of α-MoO3 film is 6.075 µm. To better understand the physical mechanism, we analyze the transverse electric and transverse magnetic wave components in the transmitted wave for the whole structure and each layer. One can see that the strong chirality of the structure is attributed to the polarization conversion of α-MoO3 film and the selective transmissivity of Ag ribbons. In addition, the influence of the filling factor of the Ag ribbons on chirality is also studied. This work combines hyperbolic material α-MoO3 with Ag ribbons to enhance CD. Also, it provides greater freedom in the tuning of chirality. We believe that this work not only deepens the understanding of the chiral response of anisotropic materials, but also gives promise for its applications in the fields of polarization optics and biosensing.

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Enhanced circular dichroism of plasmonic chiral system due to indirect coupling of two unaligned nanorods with metal film

Cited by 5 publications

References 38 publications

Controlling the broadband enhanced light chirality with L-shaped dielectric metamaterials

Controlling the broadband enhanced light chirality with L-shaped dielectric metamaterials

Design of chiral plasmonic metamaterials based on interpretable deep learning

Enhanced chirality induced in a composite structure consisting of α-MoO₃ film and a silver metasurface

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Enhanced circular dichroism of plasmonic chiral system due to indirect coupling of two unaligned nanorods with metal film

Cited by 5 publications

References 38 publications

Controlling the broadband enhanced light chirality with L-shaped dielectric metamaterials

Controlling the broadband enhanced light chirality with L-shaped dielectric metamaterials

Design of chiral plasmonic metamaterials based on interpretable deep learning

Enhanced chirality induced in a composite structure consisting of α-MoO3 film and a silver metasurface

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Enhanced chirality induced in a composite structure consisting of α-MoO₃ film and a silver metasurface