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Hasebe H, Sugimoto H, Katsurayama Y, Furuyama T, Fujii M. Photosensitizing Metasurface Empowered by Enhanced Magnetic Field of Toroidal Dipole Resonance. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2302519. [PMID: 37345569 DOI: 10.1002/smll.202302519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/29/2023] [Indexed: 06/23/2023]
Abstract
Photochemical reaction exploiting an excited triplet state (T1 ) of a molecule requires two steps for the excitation, i.e., electronic transition from the ground (S0 ) to singlet excited (S1 ) states and intersystem crossing to the T1 state. A dielectric metasurface coupled with photosensitizer that enables energy efficient photochemical reaction via the enhanced S0 →T1 magnetic dipole transition is developed. In the direct S0 →T1 transition, the photon energy of several hundreds of meV is saved compared to the conventional S0 → S1 →T1 transition. To maximize the magnetic field intensity on the surface, a silicon (Si) nanodisk array metasurface with toroidal dipole resonances is designed. The surface of the metasurface is functionalized with ruthenium (Ru(II)) complexes that work as a photosensitizer for singlet oxygen generation. In the coupled system, the rate of the direct S0 →T1 transition of Ru(II) complexes is 41-fold enhanced at the toroidal dipole resonance of a Si nanodisk array. The enhancement of a singlet oxygen generation rate is observed when the toroidal dipole resonance of a Si nanodisk array is matched with the direct S0 →T1 transition wavelength of Ru(II) complexes.
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Affiliation(s)
- Hiroaki Hasebe
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Kobe, 657-8501, Japan
| | - Hiroshi Sugimoto
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Kobe, 657-8501, Japan
- JST-PRESTO, Honcho 4-1-8, Saitama, 332-0012, Japan
| | - Yoshino Katsurayama
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, 920-1192, Japan
| | - Taniyuki Furuyama
- JST-PRESTO, Honcho 4-1-8, Saitama, 332-0012, Japan
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, 920-1192, Japan
| | - Minoru Fujii
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Kobe, 657-8501, Japan
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Ma C, Zhou F, Huang P, Li M, Zhao F, Feng Z, Liu Y, Li X, Guan BO, Chen K. Deterministic Excitation of Polarization-Sensitive Extrinsic Anapole State in Si Nanodisk Clusters. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2204883. [PMID: 36323588 DOI: 10.1002/smll.202204883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 10/12/2022] [Indexed: 06/16/2023]
Abstract
Nanoparticle clusters provide new degrees of freedom for light control due to their mutual interaction compared with an individual one. Here, the authors demonstrate theoretically and experimentally a type of optical anapole (a nonradiating state) termed as extrinsic anapole, with mode field spreading across Si nanodisk dimers unlike the intrinsic one that is confined within individual nanodisks. The extrinsic anapole is sensitive to the polarized excitation. When the electric vector E of excitation is perpendicular to the dimer axis, the coupled toroidal dipole (TD) mode is largely enhanced and broadened to be spectrally overlapped with the electric dipole (ED) mode. The destructive interference of these two modes results in the generation of the extrinsic anapole. However, it vanishes when E is parallel to the dimer axis. Such polarization dependence can be relieved with the participation of the third nanodisk. Scattering spectra of Si nanodisk trimers stay almost unchanged under different polarized excitations, although the near-field distributions are quite different. Finally, enhanced white-light emission is observed in Si nanodisk clusters, which can be attributed to the near-infrared absorption enhancement induced by extrinsic anapole states. The findings manifest that high-index all-dielectric nanodisk clusters are promising for light manipulation based on mode interference.
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Affiliation(s)
- Churong Ma
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Fangrong Zhou
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Pengfei Huang
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Meng Li
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Feng Zhao
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Ziwei Feng
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Ying Liu
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Xiangping Li
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Bai-Ou Guan
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
| | - Kai Chen
- Guangdong Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, P. R. China
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Meng B, Wang J, Zhou C, Huang L. Bound states in the continuum supported by silicon oligomer metasurfaces. OPTICS LETTERS 2022; 47:1549-1552. [PMID: 35290361 DOI: 10.1364/ol.453076] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Oligomer metasurfaces have attracted a lot of attention in recent years because of their ability to drive strong resonance effects. In this work, by perturbing the symmetry of the structure, we find that there are a large number of resonance modes in the oligomer metasurfaces associated with the optical bound states in the continuum (BICs) near the communication wavelength. When the positions of two nanodisks of the hexamer oligomers are moved along the x- or y-directions at the same time, the mirror symmetry is broken, and an electric quadrupole BIC and three magnetic dipole BICs are excited. The results of near-field distribution of three-dimensional nanodisks and far-field scattering of multiple dipoles in each quasi-BIC reveal that the four BICs present different optical characteristics. It is noted that the method of symmetry breaking by moving the position of nanodisks can accurately control the asymmetric parameter of symmetry-protected BICs, which provides a route for the realization of ultrahigh quality (Q)-factor oligomer metasurfaces in experiment.
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Liu L, Ge L. Toroidal dipole resonances by a sub-wavelength all-dielectric torus. OPTICS EXPRESS 2022; 30:7491-7500. [PMID: 35299510 DOI: 10.1364/oe.451499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/06/2022] [Indexed: 06/14/2023]
Abstract
Electromagnetic toroidal excitations open up a new avenue for strong light-matter interactions. Although toroidal dipole resonances (TDRs) based on artificial meta-molecules were reported intensely, the TDRs supported in a single dielectric particle remain largely unknown. In this work, we show that an all-dielectric sub-wavelength torus can support a dominant TDR. The magnetic field can be enhanced greatly, and it shows a "vortex-like" configuration in the torus, confirming the toroidal excitation. The evolutions of the TDRs due to the geometrical parameters, dielectric permittivity, and polarization are discussed. It is found that the toroidal excitation is achieved mainly for TM polarization, while the anapole state is uncovered for TE polarization. This work suggests a new strategy for toroidal excitations based on a simple dielectric resonator.
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Dmitriev V, Santos SDS, Kupriianov AS, Tuz VR. Transition between toroidic orders in dielectric metasurfaces by polarization of the incident wave. OPTICS LETTERS 2021; 46:2964-2967. [PMID: 34129585 DOI: 10.1364/ol.428529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
We propose a design and perform a theoretical and experimental study of optical properties of a metasurface composed of hexagonal oligomers of dielectric particles that somewhat resemble characteristics of multiferroics. It can maintain both toroidic and antitoroidic orders in the dynamical response on irradiation by a linearly polarized plane wave. These orders originate from the dark states of toroidal dipole moments. Due to the consciously chosen perturbation in the oligomers, the orders are excited at the same frequency by the wave with orthogonal polarization. The excitation of these orders results in different characteristics of the electric near-field localization. This has significant potential for several applications, which are thoroughly discussed.
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Rana AS, Kim I, Ansari MA, Anwar MS, Saleem M, Tauqeer T, Danner A, Zubair M, Mehmood MQ, Rho J. Planar Achiral Metasurfaces-Induced Anomalous Chiroptical Effect of Optical Spin Isolation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:48899-48909. [PMID: 32981321 DOI: 10.1021/acsami.0c10006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Planar chiral structures respond differently for oppositely handed incident light, and thus can produce extraordinary chiroptical effects such as circular conversion dichroism (CCD) and asymmetric transmission (AT). Such chiroptical effects are powerful tools to realize the fundamental principle of optical spin isolation, which leads to a plethora of applications such as optical conversion diodes, chiral imaging, and sensing. Here, we demonstrate the chiroptical effects of simultaneous CCD and AT through meticulously designed single-layered achiral nanofins. Our metamolecule consists of four achiral hydrogenated amorphous silicon (a-Si:H) nanofins that are carefully oriented and optimized to exhibit considerable CCD and AT. The device demonstrates a circular conversion dichroism of 55% and an asymmetric transmission of 58% at a wavelength of 633 nm. Right-hand circularly polarized light (RHCP) is completely absorbed, while left-hand circularly polarized light (LHCP) is transmitted with a polarization conversion, making it a perfect circular polarization wave isolator with negligible backscattering (due to low reflectance). This unique design and its underlying working mechanism are described comprehensively with three different techniques. These methods validate the proposed design and its methodology. For practical applications such as imaging, the proposed design realizes the Pancharatnam-Berry (PB) phase, achieving a 0-2π phase coverage for transmitted circular polarization. For the proof of concept, a metahologram is designed and demonstrated by employing the achieved full-phase control. The measured response of the fabricated metadevice not only validates the CCD and AT but also exhibits a simulated polarization conversion efficiency of up to 71% and measured efficiency up to 52%, comparable to state-of-the-art metahologram demonstrations.
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Affiliation(s)
- Ahsan Sarwar Rana
- NanoTech Lab, Department of Electrical Engineering, Information Technology University of the Punjab, Ferozepur Road, Lahore 54600, Pakistan
| | - Inki Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Muhammad Afnan Ansari
- NanoTech Lab, Department of Electrical Engineering, Information Technology University of the Punjab, Ferozepur Road, Lahore 54600, Pakistan
| | - Muhammad Sabieh Anwar
- Laboratory for Quantum Technologies, Department of Physics, Syed Babar Ali School of Science and Engineering (SBASSE), Lahore University of Management Sciences (LUMS), Opposite Sector U, DHA Lahore 54792, Pakistan
| | - Murtaza Saleem
- Laboratory for Quantum Technologies, Department of Physics, Syed Babar Ali School of Science and Engineering (SBASSE), Lahore University of Management Sciences (LUMS), Opposite Sector U, DHA Lahore 54792, Pakistan
| | - Tauseef Tauqeer
- NanoTech Lab, Department of Electrical Engineering, Information Technology University of the Punjab, Ferozepur Road, Lahore 54600, Pakistan
| | - Aaron Danner
- Department of Electrical and Computer Engineering, National University of Singapore, 117583 Singapore, Singapore
| | - Muhammad Zubair
- NanoTech Lab, Department of Electrical Engineering, Information Technology University of the Punjab, Ferozepur Road, Lahore 54600, Pakistan
| | - Muhammad Qasim Mehmood
- NanoTech Lab, Department of Electrical Engineering, Information Technology University of the Punjab, Ferozepur Road, Lahore 54600, Pakistan
| | - Junsuk Rho
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- National Institute of Nanomaterials Technology (NINT), Pohang 37673, Republic of Korea
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Raad SH, Atlasbaf Z. Broadband continuous/discrete spectrum optical absorber using graphene-wrapped fractal oligomers. OPTICS EXPRESS 2020; 28:18049-18058. [PMID: 32680006 DOI: 10.1364/oe.396500] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 05/27/2020] [Indexed: 06/11/2023]
Abstract
In this paper, a second-order fractal oligomer constructed by graphene-coated cylindrical nano-rods is proposed as the unit cell of a wideband optical absorber. Nano-rods have resided on a dielectric substrate with a thick metallic mirror. The fractional bandwidth of the designed structure is 88.67% for the absorption above 90%. Broadband absorption originates from the cooperative excitation of localized surface plasmon resonances (LSPRs) of the bottom, top, and lateral surfaces of the rods, engineered by the geometrical parameters through the fractal concept. Designed full absorber has an acceptable performance concerning the incident angles up to around 35° and it is polarization insensitive. Moreover, broadband absorption can be altered to multi-band performance in the same spectrum with the desired number of frequency bands. This feature is obtained by manipulating the substrate thickness to excite multiple orders of Fabry-Perot cavity resonances. Our proposed structure has potential applications in various optical devices such as filters, sensors, and modulators.
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Wang X, Li S, Zhou C. Polarization-independent toroidal dipole resonances driven by symmetry-protected BIC in ultraviolet region. OPTICS EXPRESS 2020; 28:11983-11989. [PMID: 32403699 DOI: 10.1364/oe.389469] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/01/2020] [Indexed: 05/22/2023]
Abstract
Optical resonances have gained great attention in nanophotonics attributing to their large enhancement of local field. In this work, we investigate polarization-independent toroidal dipole responses governed by bound state in the continuum (BIC) in the ultraviolet region. By introducing symmetry breaking, an asymmetric dielectric nanohole array is employed to excite two symmetry-protected BICs. Far-field contribution and near-field analysis are performed to demonstrate the dominant role of toroidal dipole in the above two modes. Our design shows the same responses under incident plane wave with different polarizations. The calculated enhancement factors also validate that these resonances can produce strong local field enhancement. Our work may provide a route towards resonators with polarization-independent responses and good performance.
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Zhou C, Li S, Fan M, Wang X, Xu Y, Xu W, Xiao S, Hu M, Liu J. Optical radiation manipulation of Si-Ge 2Sb 2Te 5 hybrid metasurfaces. OPTICS EXPRESS 2020; 28:9690-9701. [PMID: 32225571 DOI: 10.1364/oe.389968] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/06/2020] [Indexed: 06/10/2023]
Abstract
Active optical metadevices have attracted growing interest for the use in nanophotonics owing to their flexible control of optics. In this work, by introducing the phase-changing material Ge2Sb2Te5 (GST), which exhibits remarkably different optical properties in different crystalline states, we investigate the active optical radiation manipulation of a resonant silicon metasurface. A designed double-nanodisk array supports a strong toroidal dipole excitation and an obvious electric dipole response. When GST is added, the toroidal response is suppressed, and the toroidal and electric dipoles exhibit pronounced destructive interference owing to the similarity of their far-field radiation patterns. When the crystallization ratio of GST is varied, the optical radiation strength and spectral position of the scattering minimum can be dynamically controlled. Our work provides a route to flexible optical radiation modulation using metasurfaces.
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