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Zhao Y, Galiautdinov A, Tie J. The N-Oscillator Born-Kuhn Model: An In-Depth Analysis of Chiro-Optical Properties in Complex Chiral Systems. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:270. [PMID: 38334541 PMCID: PMC10856515 DOI: 10.3390/nano14030270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 02/10/2024]
Abstract
A comprehensive theory is developed for the chiral optical response of two configurations of the N-oscillator Born-Kuhn model (NOBK): the helically stacked and the corner stacked models. In the helical NOBK model, there is always a chiral response regardless of the value of N, whereas in the corner NOBK, only configurations with even N demonstrate a chiral response. Generally, the magnitudes of optical rotatory dispersion (ORD) and circular dichroism (CD) increase with N when the parameters of each oscillator are fixed. In cases of weak coupling, the spectral shapes of ORD and CD remain invariant, while strong coupling significantly alters the spectral shapes. For large damping, the spectral amplitude becomes smaller, and the spectral features become broader. In the presence of small damping, strong coupling introduces degeneracy in the coupled oscillator system, leading to multiple spectral features in both ORD and CD across the entire spectral region. This simple model can not only help in the design of tunable chiral metamaterials but also enhance our understanding of chiro-optical responses in structures with different configurations.
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Affiliation(s)
- Yiping Zhao
- Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602, USA;
| | - Andrei Galiautdinov
- Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602, USA;
| | - Jingzhi Tie
- Department of Mathematics, The University of Georgia, Athens, GA 30602, USA;
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2
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Han JH, Lim YC, Kim RM, Lv J, Cho NH, Kim H, Namgung SD, Im SW, Nam KT. Neural-Network-Enabled Design of a Chiral Plasmonic Nanodimer for Target-Specific Chirality Sensing. ACS NANO 2023; 17:2306-2317. [PMID: 36648062 DOI: 10.1021/acsnano.2c08867] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Quantitative analysis of chiral molecules in various solvents is essential. However, there are still many challenges to enhancing the sensitivity in precisely determining both concentration and chirality. Here, we built an algorithmic methodology to predict and optimally design the chiroptical response of chiral plasmonic sensors for a specific target chiral analyte with the aid of deep learning. Based upon the analytic and intuitive understanding of the Born-Kuhn type plasmonic nanodimer, we designed and trained the neural networks that can successfully predict the chiroptical properties and further inversely design the plasmonic structure to achieve the intended circular dichroism. The developed algorithm could identify the optimum structure exhibiting the maximum sensitivity for the given specific analytes. Surprisingly, we discovered that sensitivity strongly depends on the various conditions of analytes and can be finely tuned with the structural parameters of plasmonic nanodimers. We envision that this study can provide a general platform to develop ultrasensitive chiral plasmonic sensors whose structure and sensitivity have been evolved algorithmically for adoption in specific applications.
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Affiliation(s)
- Jeong Hyun Han
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
| | - Yae-Chan Lim
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
| | - Ryeong Myeong Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
| | - Jiawei Lv
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
| | - Nam Heon Cho
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
| | - Hyeohn Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
| | - Seok Daniel Namgung
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
| | - Sang Won Im
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
| | - Ki Tae Nam
- Department of Materials Science and Engineering, Seoul National University, Seoul08826, Republic of Korea
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3
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Cao Z, Chen J, Deng S, Chen H. A physical interpretation of coupling chiral metaatoms. NANOSCALE 2022; 14:3849-3857. [PMID: 35195644 DOI: 10.1039/d1nr05065f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The physical origins of chiroptical responses from artificial optically active media are significant for developing high-performance circular dichroism (CD) spectroscopic techniques. Here, we present a biorthogonal approach based on temporal coupled-mode theory to unravel the underlying physics of chiral metasurfaces. Equipped with physically meaningful parameters, this approach inherits the intrinsic properties of open optical cavities, including time-reversal symmetry and non-Hermitian Hamiltonians, which are found to be in excellent agreement with numerical results. Remarkably, it identifies that the intrinsic chirality of coupled chiral nanocavities arises from (i) the asymmetric coupling between interlayer cross-polarized resonant modes and (ii) a coherent interference between doubly degenerate states. Based on this formalism, a critical coupling condition capable of achieving zero transmission for circularly polarized light is proposed.
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Affiliation(s)
- Zhaolong Cao
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Jianfa Chen
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Shaozhi Deng
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Huanjun Chen
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
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Zu S, Sun Q, Cao E, Oshikiri T, Misawa H. Revealing the Chiroptical Response of Plasmonic Nanostructures at the Nanofemto Scale. NANO LETTERS 2021; 21:4780-4786. [PMID: 34048263 DOI: 10.1021/acs.nanolett.1c01322] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The spatiotemporal origin of plasmonic chiroptical responses in nanostructures remains unexplored and unclear. Here, two orthogonally oriented Au nanorods as a prototype were investigated, with a giant chiroptical response caused by antisymmetric and symmetric mode excitations for obliquely incident left-handed circular polarization (LCP) and right-handed circular polarization (RCP) light. Time-resolved photoemission electron microscopy (PEEM) was employed to measure the near-field spatial distributions, spectra, and spatiotemporal dynamics of plasmonic modes associated with the chiroptical responses at the nanofemto scale, verifying the characteristic near-field distributions at the resonant wavelengths of the two modes and a very large spectral dichroism for LCP and RCP. More importantly, eigenmode excitations and their contributions to the ultrafast plasmonic chiroptical response in the space-time domain were directly revealed, promoting a full understanding of the ultrafast chiral origin in complex nanostructures. These findings open a way to design chiroptical nanophotonic devices for spatiotemporal control of chiral light-matter interactions.
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Affiliation(s)
- Shuai Zu
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Quan Sun
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan
| | - En Cao
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Tomoya Oshikiri
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Hiroaki Misawa
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan
- Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
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5
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Long- and short-ranged chiral interactions in DNA-assembled plasmonic chains. Nat Commun 2021; 12:2025. [PMID: 33795690 PMCID: PMC8016906 DOI: 10.1038/s41467-021-22289-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 03/04/2021] [Indexed: 02/01/2023] Open
Abstract
Circular dichroism (CD) has long been used to trace chiral molecular states and changes of protein configurations. In recent years, chiral plasmonic nanostructures have shown potential for applications ranging from pathogen sensing to novel optical materials. The plasmonic coupling of the individual elements of such metallic structures is a crucial prerequisite to obtain sizeable CD signals. We here identify and implement various coupling entities-chiral and achiral-to demonstrate chiral transfer over distances close to 100 nm. The coupling is realized by an achiral nanosphere situated between a pair of gold nanorods that are arranged far apart but in a chiral fashion using DNA origami. The transmitter particle causes a strong enhancement of the CD response, the emergence of an additional chiral feature at the resonance frequency of the nanosphere, and a redshift of the longitudinal plasmonic resonance frequency of the nanorods. Matching numerical simulations elucidate the intricate chiral optical fields in complex architectures.
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Ni J, Liu S, Hu G, Hu Y, Lao Z, Li J, Zhang Q, Wu D, Dong S, Chu J, Qiu CW. Giant Helical Dichroism of Single Chiral Nanostructures with Photonic Orbital Angular Momentum. ACS NANO 2021; 15:2893-2900. [PMID: 33497201 DOI: 10.1021/acsnano.0c08941] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Optical activity, demonstrating the chiral light-matter interaction, has attracted tremendous attention in both fundamental theoretical research and advanced applications of high-efficiency enantioselective sensing and next-generation chiroptical spectroscopic techniques. However, conventional chiroptical responses are normally limited in large assemblies of chiral materials by circularly polarized light, exhibiting extremely weak chiroptical signals in a single chiral nanostructure. Here, we demonstrate that an alternative chiral freedom of light-orbital angular momentum-can be utilized for generating strong helical dichroism in single chiral nanostructures. The helical dichroism by monochromatic vortex beams can unambiguously distinguish the intrinsic chirality of nanostructures, in an excellent agreement with theoretical predictions. The single planar-chiral nanostructure can exhibit giant helical dichroism of ∼20% at the visible wavelength. The vortex-dependent helical dichroism, expanding to single nanostructures and two-dimensional space, has implications for high-efficiency chiroptical detection of planar-chiral nanostructures in chiral optics and nanophotonic systems.
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Affiliation(s)
- Jincheng Ni
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Shunli Liu
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Guangwei Hu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Yanlei Hu
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Zhaoxin Lao
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Jiawen Li
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Qing Zhang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Dong Wu
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Shaohua Dong
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Jiaru Chu
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
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Davis MS, Zhu W, Strait J, Lee JK, Lezec HJ, Blair S, Agrawal A. Chiroptical Response of Aluminum Nanocrescents at Ultraviolet Wavelengths. NANO LETTERS 2020; 20:3656-3662. [PMID: 32315534 PMCID: PMC7539542 DOI: 10.1021/acs.nanolett.0c00586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Manipulation of plasmon modes at ultraviolet wavelengths using engineered nanophotonic devices allows for the development of high-sensitivity chiroptical spectroscopy systems. We present here an experimental framework based on aluminum-based crescent-shaped nanostructures that exhibit a strong chiroptical response at ultraviolet wavelengths. Through utilization of higher-order plasmon modes in wavelength-scale nanostructures, we address the inherent fabrication challenges in scaling the response to higher frequencies. Additionally, the distinct far-field spectral response types are analyzed within a coupled-oscillator model framework. We find two competing chiroptical response types that contribute toward potential ambiguity in the interpretation of the circular dichroism spectra. The first, optical activity, originates from the interaction between hybridized eigenmodes, whereas the second manifests as a response superficially similar to optical activity but originating instead from differential near-field absorption modes. The study of the chiroptical response from nanoplasmonic devices presented here is expected to aid the development of next-generation chiroptical spectroscopy systems.
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Affiliation(s)
- Matthew S. Davis
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Maryland NanoCenter, University of Maryland, College Park, MD 20742, USA
- Department of Electrical Engineering and Computer Science, Syracuse University, Syracuse, NY 13244, USA
| | - Wenqi Zhu
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Maryland NanoCenter, University of Maryland, College Park, MD 20742, USA
| | - Jared Strait
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Jay K. Lee
- Department of Electrical Engineering and Computer Science, Syracuse University, Syracuse, NY 13244, USA
| | - Henri J. Lezec
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Steve Blair
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA
| | - Amit Agrawal
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Maryland NanoCenter, University of Maryland, College Park, MD 20742, USA
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