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Oleynik P, Berkmann F, Reiter S, Schlipf J, Ratzke M, Yamamoto Y, Fischer IA. Strong Optical Coupling of Lattice Resonances in a Top-down Fabricated Hybrid Metal-Dielectric Al/Si/Ge Metasurface. NANO LETTERS 2024; 24:3142-3149. [PMID: 38427383 PMCID: PMC10941247 DOI: 10.1021/acs.nanolett.3c05050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/02/2024]
Abstract
Optical metasurfaces enable the manipulation of the light-matter interaction in ultrathin layers. Compared with their metal or dielectric counterparts, hybrid metasurfaces resulting from the combination of dielectric and metallic nanostructures can offer increased possibilities for interactions between modes present in the system. Here, we investigate the interaction between lattice resonances in a hybrid metal-dielectric metasurface obtained from a single-step nanofabrication process. Finite-difference time domain simulations show the avoided crossing of the modes appearing in the wavelength-dependent absorptance inside the Ge upon variations in a selected geometry parameter as evidence for strong optical coupling. We find good agreement between the measured and simulated absorptance and reflectance spectra. Our metasurface design can be easily incorporated into a top-down optoelectronic device fabrication process with possible applications ranging from on-chip spectroscopy to sensing.
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Affiliation(s)
- Paul Oleynik
- Experimentalphysik
und Funktionale Materialien, Brandenburgische
Technische Universität Cottbus-Senftenberg, Erich-Weinert-Straße 1, 03046, Cottbus, Germany
| | - Fritz Berkmann
- Department
of Physics, Sapienza University of Rome, 00185 Rome, Italy
| | - Sebastian Reiter
- Experimentalphysik
und Funktionale Materialien, Brandenburgische
Technische Universität Cottbus-Senftenberg, Erich-Weinert-Straße 1, 03046, Cottbus, Germany
| | - Jon Schlipf
- Experimentalphysik
und Funktionale Materialien, Brandenburgische
Technische Universität Cottbus-Senftenberg, Erich-Weinert-Straße 1, 03046, Cottbus, Germany
| | - Markus Ratzke
- Experimentalphysik
und Funktionale Materialien, Brandenburgische
Technische Universität Cottbus-Senftenberg, Erich-Weinert-Straße 1, 03046, Cottbus, Germany
| | - Yuji Yamamoto
- IHP−Leibniz
Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236, Frankfurt (Oder), Germany
| | - Inga Anita Fischer
- Experimentalphysik
und Funktionale Materialien, Brandenburgische
Technische Universität Cottbus-Senftenberg, Erich-Weinert-Straße 1, 03046, Cottbus, Germany
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Ravishankar AP, Vennberg F, Anand S. Strong optical coupling in metallo-dielectric hybrid metasurfaces. OPTICS EXPRESS 2022; 30:42512-44524. [PMID: 36366704 DOI: 10.1364/oe.473358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Metasurfaces consisting of hybrid metal/dielectric nanostructures carry advantages of both material platforms. The hybrid structures can not only confine electromagnetic fields in subwavelength regions, but they may also lower the absorption losses. Such optical characteristics are difficult to realize in metamaterials with only metal or dielectric structures. Hybrid designs also expand the scope of material choices and the types of optical modes that can be excited in a metasurface, thereby allowing novel light matter interactions. Here, we present a metallo-dielectric hybrid metasurface design consisting of a high-index dielectric (silicon) nanodisk array on top of a metal layer (aluminum) separated by a buffer oxide (silica) layer. The dimensions of Si nanodisks are tuned to support anapole states and the period of the nanodisk array is designed to excite surface plasmon polariton (SPP) at the metal-buffer oxide interface. The physical dimensions of the Si nanodisk and the array periods are optimized to excite the anapole and the SPP at normal incidence of light in the visible-NIR (400-900 nm) wavelength range. Finite difference time domain (FDTD) simulations show that, when the nanodisk grating is placed at a specific height (∼200 nm) from the metal surface, the two modes strongly couple at zero detuning of the resonances. The strong coupling is evident from the avoided crossing of the modes observed in the reflectance spectra and in the spectral profile of light absorption inside the Si nanodisk. A vacuum Rabi splitting of up to ∼ 129 meV is achievable by optimizing the diameters of Si nanodisk and the nanodisk array grating period. The proposed metasurface design is promising to realize open cavity strongly coupled optical systems operating at room temperatures.
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Sun B, Yu Y, Zhu H, Yang W. High Q-factor with spoof-anapole mode excitation in metamaterials. OPTICS LETTERS 2021; 46:2630-2633. [PMID: 34061074 DOI: 10.1364/ol.425389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 04/30/2021] [Indexed: 06/12/2023]
Abstract
In this Letter, numerical and experimental studies for the spoof-anapole effect are presented. Different from the anapole modes, when electric and toroidal dipole intensities are minimized, the spoof-anapole effect can be generated. The spoof-anapole effect can reduce the radiation losses with a high $Q$-factor. The concept is valid in various frequency bands from microwave range for millimeter-sized objects to visible range for nanoparticles. The spoof-anapole modes are first experimentally realized in microwave metamaterials. Almost perfect spoof-anapole behavior is observed, which produces an extremely high $Q$-factor at the resonance frequency. The experimental results agree well with the analytical ones and pave way to excite the non-radiating electromagnetic sources.
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Parker JA, Sugimoto H, Coe B, Eggena D, Fujii M, Scherer NF, Gray SK, Manna U. Excitation of Nonradiating Anapoles in Dielectric Nanospheres. PHYSICAL REVIEW LETTERS 2020; 124:097402. [PMID: 32202870 DOI: 10.1103/physrevlett.124.097402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 01/27/2020] [Indexed: 05/28/2023]
Abstract
Although the study of nonradiating anapoles has long been part of fundamental physics, the dynamic anapole at optical frequencies was only recently experimentally demonstrated in a specialized silicon nanodisk structure. We report excitation of the electrodynamic anapole state in isotropic silicon nanospheres using radially polarized beam illumination. The superposition of equal and out-of-phase amplitudes of the Cartesian electric and toroidal dipoles produces a pronounced dip in the scattering spectra with the scattering intensity almost reaching zero-a signature of anapole excitation. The total scattering intensity associated with the anapole excitation is found to be more than 10 times weaker for illumination with radially vs linearly polarized beams. Our approach provides a simple, straightforward alternative path to realizing nonradiating anapole states at the optical frequencies.
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Affiliation(s)
- John A Parker
- The James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Hiroshi Sugimoto
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan
| | - Brighton Coe
- Department of Physics, Illinois State University, Normal, Illinois 61709, USA
| | - Daniel Eggena
- Department of Physics, Illinois State University, Normal, Illinois 61709, USA
| | - Minoru Fujii
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan
| | - Norbert F Scherer
- The James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, USA
| | - Stephen K Gray
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Uttam Manna
- Department of Physics, Illinois State University, Normal, Illinois 61709, USA
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Yang Y, Bozhevolnyi SI. Nonradiating anapole states in nanophotonics: from fundamentals to applications. NANOTECHNOLOGY 2019; 30:204001. [PMID: 30695763 DOI: 10.1088/1361-6528/ab02b0] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Nonradiating sources are nontrivial charge-current distributions that do not generate fields outside the source domain. The pursuit of their possible existence has fascinated several generations of physicists and triggered developments in various branches of science ranging from medical imaging to dark matter. Recently, one of the most fundamental types of nonradiating sources, named anapole states, has been realized in nanophotonics regime and soon spurred considerable research efforts and widespread interest. A series of astounding advances have been achieved within a very short period of time, uncovering the great potential of anapole states in many aspects such as lasing, sensing, metamaterials, and nonlinear optics. In this review, we provide a detailed account of anapole states in nanophotonics research, encompassing their basic concepts, historical origins, and new physical effects. We discuss the recent research frontiers in understanding and employing optical anapoles and provide an outlook for this vibrant field of research.
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Affiliation(s)
- Yuanqing Yang
- Centre for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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Guo K, Guo Z. Enhanced Second-Harmonic Generation from Fanolike Resonance in an Asymmetric Homodimer of Gold Elliptical Nanodisks. ACS OMEGA 2019; 4:1757-1762. [PMID: 31459432 PMCID: PMC6648872 DOI: 10.1021/acsomega.8b02986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 12/19/2018] [Indexed: 06/10/2023]
Abstract
In this article, we have investigated the enhanced second-harmonic generation (SHG) from Fanolike resonance in an asymmetric homodimer of gold elliptical nanodisks using a three-dimensional finite element method. We have found that the broken symmetry will cause Fanolike resonances in the extinction spectrum, resulting in the enhancement of SHG efficiency. When one of the gold elliptical nanodisks rotates, the SHG efficiency increases first and then decreases. In addition, we have also shown that the SHG signal blue-shifts with the reduction of efficiency when the separation between two nanodisks increases. Furthermore, when the nanodisks become thicker, the SHG signal also blue-shifts with the increase of efficiency. The SHG signal from this simple plasmonic structure with high efficiency and tunability may pave a way toward practical applications in sensing and generating a new light source.
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Liu SD, Wang ZX, Wang WJ, Chen JD, Chen ZH. High Q-factor with the excitation of anapole modes in dielectric split nanodisk arrays. OPTICS EXPRESS 2017; 25:22375-22387. [PMID: 29041549 DOI: 10.1364/oe.25.022375] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 08/31/2017] [Indexed: 06/07/2023]
Abstract
The simultaneous realization of high Q-factor resonances and strong near-field enhancements around and inside of dielectric nanostructures is important for many applications in nanophotonics. However, the incident fields are often confined within dielectric nanoparticles, which results in poor optical interactions with external environment. Near-field enhancements can be extended outside of dielectric nanostructures with proper design, but the Q-factor is often reduced caused by additional radiation losses. This paper shows that the obstacles to achieve high Q-factor, that is, the radiative losses can be effectively suppressed by using dielectric nanodisk arrays, where the Q-factor is about one order larger than that of the single disks associated with the nonradiating anapole modes and the collective oscillations of the arrays. When the resonance energies of the electric dipole mode and the subradiant mode are degenerate with each other, the destructive interference produces an effect analogous to electromagnetically induced transparency. Furthermore, the Q-factor can be extremely enlarged with dielectric split nanodisk arrays, where the present of the split gap does not induce additional losses. Instead, the coupling between the two interfering modes is modified by adjusting the gap width, which makes it possible to achieve high Q-factor and strong near-field enhancements around and inside of the split disks simultaneously. It is shown that the Q-factor is approaching to 106 when the gap width is about 110 nm, and the near-field enhancements around and inside of the split disks are about two orders stronger than that of the single disk.
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Shibanuma T, Grinblat G, Albella P, Maier SA. Efficient Third Harmonic Generation from Metal-Dielectric Hybrid Nanoantennas. NANO LETTERS 2017; 17:2647-2651. [PMID: 28288274 DOI: 10.1021/acs.nanolett.7b00462] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
High refractive index dielectric nanoantennas are expected to become key elements for nonlinear nano-optics applications due to their large nonlinearities, low energy losses, and ability to produce high electric field enhancements in relatively large nanoscale volumes. In this work, we show that the nonlinear response from a high-index dielectric nanoantenna can be significantly improved by adding a metallic component to build a metal-dielectric hybrid nanostructure. We demonstrate that the plasmonic resonance of a Au nanoring can boost the anapole mode supported by a Si nanodisk, strongly enhancing the electric field inside the large third-order susceptibility dielectric. As a result, a high third harmonic conversion efficiency, which reaches 0.007% at a third harmonic wavelength of 440 nm, is obtained. In addition, by suitably modifying geometrical parameters of the hybrid nanoantenna, we tune the enhanced third harmonic emission throughout the optical regime. Coupling metallic and dielectric nanoantennas to expand the potential of subwavelength structures opens new paths for efficient nonlinear optical effects in the visible range on the nanoscale.
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Affiliation(s)
- Toshihiko Shibanuma
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
- Central Technical Research Laboratory, JX Nippon Oil & Energy Corporation , 8, Chidori-cho, Naka-ku, Yokohama 231-0815, Japan
| | - Gustavo Grinblat
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
| | - Pablo Albella
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
- University Institute for Intelligent Systems and Numerical Applications in Engineering (SIANI) University of Las Palmas de Gran Canaria, 35017, Las Palmas de Gran Canaria, Spain
| | - Stefan A Maier
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
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Totero Gongora JS, Favraud G, Fratalocchi A. Fundamental and high-order anapoles in all-dielectric metamaterials via Fano-Feshbach modes competition. NANOTECHNOLOGY 2017; 28:104001. [PMID: 28145277 DOI: 10.1088/1361-6528/aa593d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
One of the most fascinating possibilities enabled by metamaterials is the strong reduction of the electromagnetic scattering from nanostructures. In dielectric nanoparticles, the formation of a minimal scattering state at specific wavelengths is associated with the excitation of photonic anapoles, which represent a peculiar type of radiationless state and whose existence has been demonstrated experimentally. In this work, we investigate the formation of anapole states in generic dielectric structures by applying a Fano-Feshbach projection scheme, a general technique widely used in the study of quantum mechanical open systems. By expressing the total scattering from the structure in terms of an orthogonal set of internal and external modes, defined in the interior and in the exterior of the dielectric structure, respectively, we show how anapole states are the result of a complex interaction among the resonances of the system and the surrounding environment. We apply our approach to a circular resonator, where we observe the formation of higher-order anapole states, which are originated by the superposition of several internal resonances of the system.
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Grinblat G, Li Y, Nielsen MP, Oulton RF, Maier SA. Efficient Third Harmonic Generation and Nonlinear Subwavelength Imaging at a Higher-Order Anapole Mode in a Single Germanium Nanodisk. ACS NANO 2017; 11:953-960. [PMID: 27977932 DOI: 10.1021/acsnano.6b07568] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Benefiting from large intrinsic nonlinearities, low absorption, and high field enhancement abilities, all-dielectric nanoantennas are considered essential for efficient nonlinear processes at subwavelength volumes. In particular, when the dielectric nanoantenna supports the nonradiating anapole mode, characterized by a minimum in the extinction cross section and a maximum electric energy within the material, third harmonic generation (THG) processes can be greatly enhanced. In this work, we demonstrate that a higher-order anapole mode in a 200 nm thick germanium nanodisk delivers the highest THG efficiency on the nanoscale at optical frequencies. By doubling the diameter of a disk supporting the fundamental anapole mode, we discover the emergence of an anapole mode of higher order, with a valley in the extinction cross section significantly narrower than that of the fundamental anapole. Under this condition, we observe a highly improved electric field confinement effect within the dielectric disk, leading to THG conversion efficiencies as large as 0.001% at a third harmonic wavelength of 550 nm. In addition, by mapping the THG emission across the nanodisk, we are able to unveil the anapole near-field intensity distributions, which show excellent agreement with numerical simulations. Our findings remarkably expand contemporary knowledge on localized modes in dielectric nanosystems, revealing crucial elements for the elaboration of highly efficient frequency upconversion nanodevices.
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Affiliation(s)
- Gustavo Grinblat
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
| | - Yi Li
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
| | - Michael P Nielsen
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
| | - Rupert F Oulton
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
| | - Stefan A Maier
- The Blackett Laboratory, Department of Physics, Imperial College London , London SW7 2AZ, United Kingdom
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