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Oubeniz H, Belkacem A, Mangach H, Kadic M, Bouzid A, Achaoui Y. Controlled Dispersion and Transmission-Absorption of Optical Energy through Scaled Metallic Plate Structures. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6146. [PMID: 37763424 PMCID: PMC10532763 DOI: 10.3390/ma16186146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/03/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023]
Abstract
The dispersive feature of metals at higher frequencies has opened up a plethora of applications in plasmonics. Besides, Extraordinary Optical Transmission (EOT) reported by Ebbesen et al. in the late 90's has sparked particular interest among the scientific community through the unprecedented and singular way to steer and enhance optical energies. The purpose of the present paper is to shed light on the effect of the scaling parameter over the whole structure, to cover the range from the near-infrared to the visible, on the transmission and the absorption properties. We further bring specific attention to the dispersive properties, easily extractable from the resonance frequency of the drilled tiny slits within the structure. A perfect matching between the analytical Rigorous Coupled Wave Analysis (RCWA), and the numerical Finite Elements Method (FEM) to describe the underlying mechanisms is obtained.
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Affiliation(s)
- Hammou Oubeniz
- Laboratory of Optics, Information Processing, Mechanics, Energetics and Electronics, Department of Physics, Moulay Ismail University, Zitoune, Meknes B.P. 11201, Morocco; (H.O.); (A.B.); (Y.A.)
| | - Abdelhaq Belkacem
- Laboratory of Optics, Information Processing, Mechanics, Energetics and Electronics, Department of Physics, Moulay Ismail University, Zitoune, Meknes B.P. 11201, Morocco; (H.O.); (A.B.); (Y.A.)
| | - Hicham Mangach
- Light, Nanomaterials Nanotechnologies (L2n), CNRS-ERL 7004, Université de Technologie de Troyes, 10000 Troyes, France
| | - Muamer Kadic
- Institut FEMTO-ST, UMR 6174, CNRS, Université de Franche-Comté, 25000 Besançon, France
| | - Abdenbi Bouzid
- Laboratory of Optics, Information Processing, Mechanics, Energetics and Electronics, Department of Physics, Moulay Ismail University, Zitoune, Meknes B.P. 11201, Morocco; (H.O.); (A.B.); (Y.A.)
| | - Younes Achaoui
- Laboratory of Optics, Information Processing, Mechanics, Energetics and Electronics, Department of Physics, Moulay Ismail University, Zitoune, Meknes B.P. 11201, Morocco; (H.O.); (A.B.); (Y.A.)
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2
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Kim S, Hong D, Sattorov M, Kim S, Yoo YJ, Park SY, Park GS. Full manipulation of transparency and absorption through direct tuning of dark modes in high-Q Fano metamaterials. OPTICS EXPRESS 2022; 30:3443-3454. [PMID: 35209602 DOI: 10.1364/oe.449968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
Controlling the line shape of Fano resonance has continued to attract significant research attention in recent years owing to its practical applications such as lasing, biosensing, and slow-light devices. However, controllable Fano resonances always require stringent alignment of complex symmetry-breaking structures; therefore, the manipulation can only be performed with limited degrees of freedom and a narrow tuning range. This work demonstrates dark-mode excitation tuning independent of the bright mode for the first time, to the authors' knowledge, in asymmetric Fano metamaterials. Metallic subwavelength slits are arranged to form asymmetric unit cells and generate a broad and bright (radiative) Fabry-Perot mode and a sharp and dark (non-radiative) surface mode. The introduction of the independent radial and angular asymmetries realizes independent control of the Fano phase (q) and quality factor (Q). This tunability provides a dynamic phase shift while maintaining a high-quality factor, enabling switching between nearly perfect transmission and absorption, which is confirmed both numerically and experimentally. The proposed scheme for fully controlled Fano systems can aid practical applications such as phase-sensitive switching devices.
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3
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Lee SG, Kim SH, Kee CS. Creation of Fano resonances and bound states in the continuum in metallic metasurface superlattices. OPTICS EXPRESS 2021; 29:21492-21501. [PMID: 34265935 DOI: 10.1364/oe.428602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/15/2021] [Indexed: 06/13/2023]
Abstract
A perfect metal film with a periodic arrangement of cut-through slits, an anisotropic metallic metamaterial film, mimics a dielectric slab and supports guided electromagnetic waves in the direction perpendicular to the slits. Since the guided Bloch modes exist only below the light line, conventional metallic metamaterial films do not exhibit interesting leaky-wave effects, such as bound states in the continuum and Fano resonances. Here, we introduce metallic metasurface superlattices that include multiple slits in a period and demonstrate that the superlattices support the Fano resonances and bound states in the continuum. We show that the number of Fano resonances and bound states depend on the number of slits in a period of superlattices through rigorous finite element method simulations. Experimental results in microwave region also support the creation of Fano resonance and bound states in the continuum by the increment of the number of slits in a period of superlattices.
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Kim J, Rana AS, Kim Y, Kim I, Badloe T, Zubair M, Mehmood MQ, Rho J. Chiroptical Metasurfaces: Principles, Classification, and Applications. SENSORS (BASEL, SWITZERLAND) 2021; 21:4381. [PMID: 34206760 PMCID: PMC8271883 DOI: 10.3390/s21134381] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/21/2021] [Accepted: 06/23/2021] [Indexed: 02/07/2023]
Abstract
Chiral materials, which show different optical behaviors when illuminated by left or right circularly polarized light due to broken mirror symmetry, have greatly impacted the field of optical sensing over the past decade. To improve the sensitivity of chiral sensing platforms, enhancing the chiroptical response is necessary. Metasurfaces, which are two-dimensional metamaterials consisting of periodic subwavelength artificial structures, have recently attracted significant attention because of their ability to enhance the chiroptical response by manipulating amplitude, phase, and polarization of electromagnetic fields. Here, we reviewed the fundamentals of chiroptical metasurfaces as well as categorized types of chiroptical metasurfaces by their intrinsic or extrinsic chirality. Finally, we introduced applications of chiral metasurfaces such as multiplexing metaholograms, metalenses, and sensors.
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Affiliation(s)
- Joohoon Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea; (J.K.); (Y.K.); (I.K.); (T.B.)
| | - Ahsan Sarwar Rana
- NanoTech Lab, Department of Electrical Engineering, Information Technology University of the Punjab, Ferozepur Road, Lahore 54600, Pakistan; (A.S.R.); (M.Z.)
| | - Yeseul Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea; (J.K.); (Y.K.); (I.K.); (T.B.)
| | - Inki Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea; (J.K.); (Y.K.); (I.K.); (T.B.)
| | - Trevon Badloe
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea; (J.K.); (Y.K.); (I.K.); (T.B.)
| | - Muhammad Zubair
- NanoTech Lab, Department of Electrical Engineering, Information Technology University of the Punjab, Ferozepur Road, Lahore 54600, Pakistan; (A.S.R.); (M.Z.)
| | - Muhammad Qasim Mehmood
- NanoTech Lab, Department of Electrical Engineering, Information Technology University of the Punjab, Ferozepur Road, Lahore 54600, Pakistan; (A.S.R.); (M.Z.)
| | - Junsuk Rho
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea; (J.K.); (Y.K.); (I.K.); (T.B.)
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea
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Corbin A, Shen JT. Ultrafast reconfigurable optical logic gates using a nonlinear metallodielectric grating. OPTICS LETTERS 2021; 46:2782-2785. [PMID: 34061112 DOI: 10.1364/ol.428737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 05/17/2021] [Indexed: 06/12/2023]
Abstract
Reconfigurable optical logic gates are developed through the design and optimization of a metallic grating with a colloidal nonlinear dielectric. The device has a structurally enhanced nonlinearity, improving power consumption and speed. Detailed design strategy and simulations for several common logic gates are provided. Using materials readily available in common CMOS processing technologies, the gates switch in sub-picosecond scales with a driving irradiance of around $200\; {{\rm MW/cm}^2}$.
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Perfect Impedance Matching with Meta-Surfaces Made of Ultra-Thin Metal Films: A Phenomenological Approach to the Ideal THz Sensors. MATERIALS 2020; 13:ma13235417. [PMID: 33260744 PMCID: PMC7730061 DOI: 10.3390/ma13235417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 11/21/2022]
Abstract
The terahertz (THz) frequency range is incredibly important as it covers electromagnetic emissions typical for biological and molecular processes. All molecules emit THz waves in a unique fingerprint pattern, although the intensity of such signals is usually too weak to be detected. To address the efficiency gap in existing THz devices it is extremely important to create surfaces with perfect anti-reflection properties. Although metals are absolutely reflective, here we show both theoretically and experimentally that by constructing meta-surfaces made of a superposition of ultra-thin metallic nano-films (a couple of nanometres thick) and oxide layers a unique property of perfect transmission and impedance matching may be realised. The perfect transmission rates can be as high as 100% and it may be achieved in both optical and THz regimes. The predicted effect has been observed for numerous meta-surfaces of different compositions. The effect found here is expected to impact the renewable energies sectors, optoelectronic and telecommunication industries, accelerating the arrival of the sensors for the new 6G-technology. The phenomenon is highly relevant to all scientific fields where minimising electromagnetic losses through reflection is important.
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Wang S, Zhai X, Shi Y, Chen L, Lv Y, Zhang Y, Ge G, Guo X. Continuous Surface Strain Tuning for NiFe-Layered Double Hydroxides Using a Multi-inlet Vortex Mixer. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c03341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shengting Wang
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, P.R. China
| | - Xingwu Zhai
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, P.R. China
- Key Laboratory of Ecophysics and Department of Physics, College of Science, Shihezi University, Shihezi 832003, P.R. China
| | - Yulin Shi
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, P.R. China
| | - Long Chen
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, P.R. China
| | - Yin Lv
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, P.R. China
| | - Yinglin Zhang
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, P.R. China
| | - Guixian Ge
- Key Laboratory of Ecophysics and Department of Physics, College of Science, Shihezi University, Shihezi 832003, P.R. China
| | - Xuhong Guo
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, P.R. China
- International Joint Research Center of Green Energy Chemical Engineering, East China University of Science and Technology, Shanghai 200237, P.R. China
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Yan R, Wang T, Jiang X, Zhong Q, Huang X, Wang L, Yue X. Design of high-performance plasmonic nanosensors by particle swarm optimization algorithm combined with machine learning. NANOTECHNOLOGY 2020; 31:375202. [PMID: 32442991 DOI: 10.1088/1361-6528/ab95b8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Metallic plasmonic nanosensors that are ultra-sensitive, label-free, and operate in real time hold great promise in the field of chemical and biological research. Conventionally, the design of these nanostructures has strongly relied on time-consuming electromagnetic simulations that iteratively solve Maxwell's equations to scan multi-dimensional parameter space until the desired sensing performance is attained. Here, we propose an algorithm based on particle swarm optimization (PSO), which in combination with a machine learning (ML) model, is used to design plasmonic sensors. The ML model is trained with the geometric structure and sensing performance of the plasmonic sensor to accurately capture the geometry-sensing performance relationships, and the well-trained ML model is then applied to the PSO algorithm to obtain the plasmonic structure with the desired sensing performance. Using the trained ML model to predict the sensing performance instead of using complex electromagnetic calculation methods allows the PSO algorithm to optimize the solutions fours orders of magnitude faster. Implementation of this composite algorithm enabled us to quickly and accurately realize a nanoridge plasmonic sensor with sensitivity as high as 142,500 nm/RIU. We expect this efficient and accurate approach to pave the way for the design of nanophotonic devices in future.
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Affiliation(s)
- Ruoqin Yan
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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Gao X, Yu FL, Cai CL, Guan CY, Shi JH, Hu F. Terahertz metamaterial with broadband and low-dispersion high refractive index. OPTICS LETTERS 2020; 45:4754-4757. [PMID: 32870849 DOI: 10.1364/ol.397230] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/07/2020] [Indexed: 06/11/2023]
Abstract
A broadband and low-dispersion high refractive index (HRI) metamaterial formed by symmetrically etching two identical metasurfaces on both sides of a dielectric slab has been numerically and experimentally demonstrated in the terahertz region. The unit cell of the metasurface is a Jerusalem cross surrounded by a square metal ring, in which there are two magnetic resonances and one electric resonance. The proposed metamaterial simultaneously possesses high effective permittivity and permeability in broadband frequencies, since the multiple resonances result in a significant bandwidth expansion of a HRI. The simulation results reveal that the refractive index of the proposed metamaterial reaches up to 27 in the frequency range of 0.39-0.65 THz, and the relative bandwidth is about 44%. Furthermore, the fluctuation of the refractive index in this frequency band is less than 6%, showing a good low-dispersion characteristic. We also fabricated a sample to verify this HRI property. Experimental results are in good agreement with numerical simulations. This broadband HRI metamaterial is desirable in many fields, such as in high-resolution imaging and optical communications.
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Chen D, Sun K, Jones AH, Campbell JC. Efficient absorption enhancement approaches for AlInAsSb avalanche photodiodes for 2-μm applications. OPTICS EXPRESS 2020; 28:24379-24388. [PMID: 32906979 DOI: 10.1364/oe.399022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
Recently, advances in imaging and LIDAR applications have stimulated the development of high-sensitivity receivers that operate at wavelengths of ≥ 2 µm, which has driven research on avalanche photodiodes (APDs) that operate in that spectral region. High quantum efficiency is a key performance parameter for these photodetectors. Increasing the thickness of the absorption region is a straightforward approach to increase the quantum efficiency. However, the primary source of dark current is the narrow-bandgap material used for 2-µm detection. Increasing its thickness results in higher noise. In this paper, we describe two approaches to enhance the quantum efficiency, both of which are superior to a conventional anti-reflection (AR) coating. For normal incidence at 2 µm, finite-difference time-domain (FDTD) simulations show the absorption can be enhanced by more than 100% with a triangular-lattice photonic crystal, and nearly 400% by applying a metal grating. This is achieved by coupling normal incidence light into the laterally propagating modes in the device. Moreover, the significantly higher absorption of the metal grating compared to the photonic crystal is due to the high coupling efficiency provided by the metal grating. This work provides promising methods and physical understanding for enhancing the quantum efficiency for 2-µm detection without increasing absorber thickness, which also enables low dark current and high bandwidth.
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11
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Dai Z, Hu G, Ou Q, Zhang L, Xia F, Garcia-Vidal FJ, Qiu CW, Bao Q. Artificial Metaphotonics Born Naturally in Two Dimensions. Chem Rev 2020; 120:6197-6246. [DOI: 10.1021/acs.chemrev.9b00592] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Zhigao Dai
- Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, 388 Lumo Road, Wuhan 430074, P.R. China
- Department of Materials Science and Engineering, ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - Guangwei Hu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore
| | - Qingdong Ou
- Department of Materials Science and Engineering, ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - Lei Zhang
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, P.R. China
| | - Fengnian Xia
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, United States
| | - Francisco J. Garcia-Vidal
- Departamento de Fisica Teorica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autonoma de Madrid, Madrid 28049, Spain
- Donostia International Physics Center (DIPC), Donostia−San Sebastian E-20018, Spain
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore
| | - Qiaoliang Bao
- Department of Materials Science and Engineering, ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), Monash University, Wellington Road, Clayton, Victoria 3800, Australia
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Mei J, Wu Y. Subwavelength acoustic monopole source emission enhancement through dual gratings. Sci Rep 2019; 9:11659. [PMID: 31406193 PMCID: PMC6690973 DOI: 10.1038/s41598-019-48215-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 07/29/2019] [Indexed: 11/17/2022] Open
Abstract
Acoustic source emission rate is generally low at low frequencies. In this work, we propose a simple design of ‘LEGO’-type acoustic metamaterial that can significantly enhance the low frequency emission rate of an acoustic monopole source. Such enhancement is resulted from the coupling between resonances of a cavity and a dual grating comprised of two concentric layers of periodically distributed narrow slits. We develop an effective medium model to characterize the enhancement. Because of its simple structure, the metamaterial is easy to fabricate and thus facilitates the applications in various domains such as oil exploration.
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Affiliation(s)
- Jun Mei
- Department of Physics, South China University of Technology, Guangzhou, 510640, China
| | - Ying Wu
- King Abdullah University of Science and Technology (KAUST), Division of Computer, Electrical and Mathematical Science and Engineering (CEMSE), Thuwal, 23955-6900, Saudi Arabia.
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Ironside DJ, Salas R, Chen PY, Le KQ, Alú A, Bank SR. Enhancing THz generation in photomixers using a metamaterial approach. OPTICS EXPRESS 2019; 27:9481-9494. [PMID: 31045099 DOI: 10.1364/oe.27.009481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/09/2019] [Indexed: 05/28/2023]
Abstract
Photomixers at THz frequencies offer an attractive solution to fill the THz gap; however, conventional photomixer designs result in low output powers, on the order of microwatts, before thermal failure. We propose an alternative photomixer design capable of orders of magnitude enhancement of continuous-wave THz generation using a metamaterial approach. By forming a metal-semiconductor-metal (MSM) cavity through layering an ultrafast semiconductor material between subwavelength metal-dielectric gratings, tailored resonance can achieve ultrathin absorbing regions and efficient heat sinking. When mounted to a tunable E-patch antenna, gratings also act as vertically biased electrodes, further enhancing photoconductive gain by reducing the carrier path length to nanoscales. Thus, through these multiplicative enhancements, the metamaterial-enhanced photomixer is projected to generate THz powers in the milliwatt range and exceed the Manley-Rowe limit for frequencies less than 2 THz.
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14
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Nanogap Engineering for Enhanced Transmission of Wire Grid Polarizers in Mid-Wavelength Infrared Region. Sci Rep 2019; 9:4201. [PMID: 30862931 PMCID: PMC6414691 DOI: 10.1038/s41598-019-40614-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 02/15/2019] [Indexed: 11/12/2022] Open
Abstract
Wire-grid polarizers (WGPs) have been widely used in various fields, such as polarimetry, imaging, display, spectroscopy, and optical isolation. However, conventional WGPs used in diverse mid-wavelength infrared (MWIR) applications show high reflection losses, which intrinsically arise from high refractive indices of their IR-transmitting substrates, such as silicon (Si) and germanium (Ge). This study demonstrated the enhanced transmittance of a transverse magnetic (TM) wave that surpassed ~80% over the entire MWIR range from 3000 to 5000 nm in a narrow air gap of a WGP, where aluminum (Al) was selectively deposited on a nanopatterned Si substrate using an oblique angle deposition method. Moreover, a higher TM wave transmittance was achieved by reducing the air gaps of the WGPs in the nanopatterns, which were distinctly different from the traditional WGPs comprising metal wires patterned directly on a flat substrate. A finite-difference time-domain simulation was performed to investigate optical properties of the proposed WGPs, which showed that the electric field in the air nanogap was remarkably enhanced. The characteristic performances were further investigated using a combination of an effective medium approximation and an admittance diagram, revealing that the broadband transmission enhancement could be attributed to a combined effect of a strong electric field and a better admittance matching. The approach and results described in this paper hold promise for the design and the fabrication of high-quality WGPs, as well as their numerous applications.
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15
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Wang R, Wu Q, Zhang Q, Lu Y, Zhao W, Cai W, Qi J, Yao J, Xu J. Conversion from terahertz-guided waves to surface waves with metasurface. OPTICS EXPRESS 2018; 26:31233-31243. [PMID: 30650712 DOI: 10.1364/oe.26.031233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 11/07/2018] [Indexed: 06/09/2023]
Abstract
Surface waves (SWs) have attracted a widespread attention due to the characteristic of subwavelength confinement and convenient manipulation in photonic integrated circuits. Though metasurface provides a powerful tool in realizing the conversion between freely propagating waves and surface modes in recent years, a gulf between guided waves (GWs) and SWs in terahertz (THz) range still exists as a bottleneck for on-chip photonic integrated devices. Here, we implemented the conversion from THz GWs to SWs through the coupling of a lithium niobate (LN) subwavelength waveguide and metasurface antennas on an all-feature on-chip THz integrated platform. The conversion process and transmission mode of the THz waves were directly visualized via a time-resolved imaging system. Based on the dynamic process, the formation of SWs could be clarified through analyzing the dispersion relation of propagating modes, which is in good agreement with numerical models. In further, relying on the numerical simulation, SWs were induced from the collective oscillations of the metasurface antenna array and the maximum coupling efficiency was around 62.6 percent. Our work provides an efficient approach to control of GWs, and promotes the practicability of THz surface integrated devices, including THz surface spectroscopy sensing.
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Gao Z, Wu L, Gao F, Luo Y, Zhang B. Spoof Plasmonics: From Metamaterial Concept to Topological Description. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1706683. [PMID: 29782662 DOI: 10.1002/adma.201706683] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/24/2018] [Indexed: 06/08/2023]
Abstract
Advances in metamaterials have offered the opportunity of engineering electromagnetic properties beyond the limits of natural materials. A typical example is "spoof" surface plasmon polaritons (SPPs), which mimic features of SPPs without penetrating into metal, but only with periodic corrugations on metal surfaces. They hold considerable promise in device applications from microwaves to the far infrared, where real SPP modes do not exist. The original spoof SPP concept is derived from the description of corrugated surfaces by a metamaterial that hosts an effective plasma frequency. Later, studies have attempted to describe spoof SPP modes with the band structure by strictly solving Maxwell's equations, which can possess band gaps from polaritonic anticrossing principle or Bragg interference. More recently, as inspired by the development of topological framework in condensed matter physics, the topological description of spoof SPPs is used to propose topologically protected waveguiding phenomena. Here, the developments of spoof SPPs from both practical and fundamental perspectives are reviewed.
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Affiliation(s)
- Zhen Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Lin Wu
- School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798, Singapore
| | - Fei Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
- State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, 310027, China
| | - Yu Luo
- School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798, Singapore
| | - Baile Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
- Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore, 637371, Singapore
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17
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Guan F, Sun S, Ma S, Fang Z, Zhu B, Li X, He Q, Xiao S, Zhou L. Transmission/reflection behaviors of surface plasmons at an interface between two plasmonic systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:114002. [PMID: 29406312 DOI: 10.1088/1361-648x/aaad2a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Although surface plasmon polaritons (SPPs) have been intensively studied in past years, the transmission/reflection properties of SPPs at an interface between two plasmonic media are still not fully understood. In this article, we employ a mode expansion method (MEM) to systematically study such a problem based on a model system jointing two superlattices, each consisting of a periodic stacking of dielectric and plasmonic slabs with different material properties. Such a generic model can represent two widely used plasmonic structures (i.e. interfaces between two single dielectric/metal systems or between two metal-insulator-metal waveguides) under certain conditions. Our MEM calculations, in excellent agreement with full-wave simulations, uncover the rich physics behind the SPP reflections at generic plasmonic interfaces. In particular, we successfully derive from the MEM several analytical formulas that can quantitatively describe the SPP reflections at different plasmonic interfaces, and show that our formulas exhibit wider applicable regions than previously proposed empirical ones.
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Affiliation(s)
- Fuxin Guan
- Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, People's Republic of China
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Zhao W, Wu Q, Wang R, Gao J, Lu Y, Zhang Q, Qi J, Zhang C, Pan C, Rupp R, Xu J. Transient establishment of the wavefronts for negative, zero, and positive refraction. OPTICS EXPRESS 2018; 26:1954-1961. [PMID: 29401916 DOI: 10.1364/oe.26.001954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 01/14/2018] [Indexed: 06/07/2023]
Abstract
We quantitatively demonstrate transient establishment of wavefronts for negative, zero, and positive refraction through a wedge-shaped metamaterial consisting of periodically arranged split-ring resonators and metallic wires. The wavefronts for the three types of refractions propagate through the second interface of the wedge along positive refraction angles at first, then reorganize, and finally propagate along the effective refraction angles after a period of establishment time respectively. The establishment time of the wavefronts prevents violating causality or superluminal propagation for negative and zero refraction. The establishment time for negative or zero refraction is longer than that for positive refraction. For all three refraction processes, transient establishment processes precede the establishment of steady propagation. Moreover, some detailed characters are proven in our research, including infinite wavelength, uniform phase inside the zero-index material, and the phase velocity being antiparallel to the group velocity in the negative-index material.
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Kolle M, Lee S. Progress and Opportunities in Soft Photonics and Biologically Inspired Optics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:1702669. [PMID: 29057519 DOI: 10.1002/adma.201702669] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 06/13/2017] [Indexed: 05/24/2023]
Abstract
Optical components made fully or partially from reconfigurable, stimuli-responsive, soft solids or fluids-collectively referred to as soft photonics-are poised to form the platform for tunable optical devices with unprecedented functionality and performance characteristics. Currently, however, soft solid and fluid material systems still represent an underutilized class of materials in the optical engineers' toolbox. This is in part due to challenges in fabrication, integration, and structural control on the nano- and microscale associated with the application of soft components in optics. These challenges might be addressed with the help of a resourceful ally: nature. Organisms from many different phyla have evolved an impressive arsenal of light manipulation strategies that rely on the ability to generate and dynamically reconfigure hierarchically structured, complex optical material designs, often involving soft or fluid components. A comprehensive understanding of design concepts, structure formation principles, material integration, and control mechanisms employed in biological photonic systems will allow this study to challenge current paradigms in optical technology. This review provides an overview of recent developments in the fields of soft photonics and biologically inspired optics, emphasizes the ties between the two fields, and outlines future opportunities that result from advancements in soft and bioinspired photonics.
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Affiliation(s)
- Mathias Kolle
- Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
| | - Seungwoo Lee
- SKKU Advanced Institute of Nanotechnology (SAINT), Department of Nano Engineering and School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
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20
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Wu HW, Han YZ, Chen HJ, Zhou Y, Li XC, Gao J, Sheng ZQ. Physical mechanism of order between electric and magnetic dipoles in spoof plasmonic structures. OPTICS LETTERS 2017; 42:4521-4524. [PMID: 29088203 DOI: 10.1364/ol.42.004521] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 10/02/2017] [Indexed: 06/07/2023]
Abstract
It has been recently shown that a solid-textured metal cylinder can support electric and magnetic dipolar resonances simultaneously [Phys. Rev. X4, 021003 (2014)PRXHAE2160-330810.1103/PhysRevX.4.021003] which are almost degenerate in a two-dimensional (2-D) structure and non-degenerate in a three-dimensional (3-D) structure, and with the magnetic dipole appearing at higher frequency. They are described as spoof localized plasmonic modes analogous to localized plasmonic resonances in optical frequencies. Here, we consider a hollow metal cylinder corrugated by periodic cut-through slits. Our results indicate that the magnetic dipole can be separated from the electric dipole in a 2-D structure, and magnetic dipolar resonance appears at lower frequency, rather than electric resonance in both 2-D and 3-D structures. In order to clarify the physical mechanism behind the abnormal phenomenon, we study the influence of the core material on the electric- and magnetic-dipole modes based on theoretical analysis and numerical simulation. It is discovered that there is a threshold of an imaginary part of permittivity for switching the order between electric and magnetic dipoles. These results may provide fundamental understanding and physical insight for spoof plasmonic modes supported in designer structures.
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21
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Liu L, Chang H, Xu T, Song Y, Zhang C, Hang ZH, Hu X. Achieving low-emissivity materials with high transmission for broadband radio-frequency signals. Sci Rep 2017; 7:4840. [PMID: 28687798 PMCID: PMC5501855 DOI: 10.1038/s41598-017-04988-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 05/22/2017] [Indexed: 11/23/2022] Open
Abstract
The use of low-emissivity (low-e) materials in modern buildings is an extremely efficient way to save energy. However, such materials are coated by metallic films, which can strongly block radio-frequency signals and prevent indoor-outdoor wireless communication. Here, we demonstrate that, when specially-designed metallic metasurfaces are covered on them, the low-e materials can remain low emissivity for thermal radiation and allow very high transmission for a broad band of radio-frequency signals. It is found that the application of air-connected metasurfaces with subwavelength periods is critical to the observed high transmission. Such effects disappear if periods are comparable to wavelengths or metal-connected structures are utilized. The conclusion is supported by both simulations and experiments. Advantages such as easy to process, low cost, large-area fabrication and design versatility of the metasurface make it a promising candidate to solve the indoor outdoor communication problem.
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Affiliation(s)
- Liu Liu
- Department of Materials Science, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education), and Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, China
| | - Huiting Chang
- Department of Materials Science, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education), and Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, China
| | - Tao Xu
- College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, China
| | - Yanan Song
- Department of Materials Science, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education), and Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, China
| | - Chi Zhang
- Department of Materials Science, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education), and Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, China
| | - Zhi Hong Hang
- College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, China.
| | - Xinhua Hu
- Department of Materials Science, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education), and Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, China.
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Tunable Terahertz Deep Subwavelength Imaging Based on a Graphene Monolayer. Sci Rep 2017; 7:46283. [PMID: 28397815 PMCID: PMC5387712 DOI: 10.1038/srep46283] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/13/2017] [Indexed: 12/19/2022] Open
Abstract
The resolution of conventional terahertz (THz) imaging techniques is limited to about half wavelength, which is not fine enough for applications of biomedical sensing and nondestructive testing. To improve the resolution, a new superlens, constructed by a monolayer graphene sheet combining with a grating voltage gate, are proposed in this paper to achieve deep super-resolution imaging in the THz frequency range. The main idea is based on the Fabry-Perot resonance of graphene edge plasmon waves. By shaping the voltage gate into a radial pattern, magnified images of subwavelength targets can be obtained. With this approach, the finest resolution can achieve up to λ/150. Besides, the superlens can be conveniently tuned to work in a large frequency band ranging from 4.3 THz to 9 THz. The proposal could find potential applications in THz near-field imaging systems.
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Lee IS, Sohn IB, Kang C, Kee CS, Yang JK, Lee JW. High refractive index metamaterials using corrugated metallic slots. OPTICS EXPRESS 2017; 25:6365-6371. [PMID: 28380988 DOI: 10.1364/oe.25.006365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on a method for realizing high refractive index metamaterials using corrugated metallic slot structures at terahertz frequencies. The effective refractive index and peak index frequency can be controlled by varying the width of the air gap in the corrugated slot arrays. The phenomenon occurs because of the secondary resonance effect due to the fundamental inductive-capacitive resonance, which generates a red-shift of the fundamental resonance determined by twice the length of the corrugated metallic slots. In addition, multiple gaps in the corrugated slots act as plasmonic hotspots which have the properties of three-dimensional subwavelength confinement due to extremely strong enhancement of the terahertz waves. The versatile characteristics of the structures may have many potential applications in designing compact optical devices incorporating various functionalities and in developing highly sensitive spectroscopic/imaging systems.
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A universal design to realize a tunable perfect absorber from infrared to microwaves. Sci Rep 2016; 6:32589. [PMID: 27599634 PMCID: PMC5013470 DOI: 10.1038/srep32589] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/04/2016] [Indexed: 11/09/2022] Open
Abstract
We propose a design for an universal absorber, characterized by a resonance frequency that can be tuned from visible to microwave frequencies independently of the choice of the metal and the dielectrics involved. An almost perfect absorption up to 99.8% is demonstrated at resonance for all polarization states of light and for a very wide angular aperture. These properties originate from a magnetic Fabry-Perot mode that is confined in a dielectric spacer of λ/100 thickness by a metamaterial layer and a mirror. An extraordinary large funneling through nano-slits explains how light can be trapped in the structure. Simple scaling laws can be used as a recipe to design ultra-thin perfect absorbers whatever the materials and the desired resonance wavelength, making our design truly universal.
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Chang T, Kim JU, Kang SK, Kim H, Kim DK, Lee YH, Shin J. Broadband giant-refractive-index material based on mesoscopic space-filling curves. Nat Commun 2016; 7:12661. [PMID: 27573337 PMCID: PMC5013611 DOI: 10.1038/ncomms12661] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 07/21/2016] [Indexed: 11/22/2022] Open
Abstract
The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials. Experimentally realized broadband refractive indices remain <40, even with intricately designed artificial media. Herein, we demonstrate a measured index >1,800 resulting from a mesoscopic crystal with a dielectric constant greater than three million. This gigantic enhancement effect originates from the space-filling curve concept from mathematics. The principle is inherently very broad band, the enhancement being nearly constant from zero up to the frequency of interest. This broadband giant-refractive-index medium promises not only enhanced resolution in imaging and raised fundamental absorption limits in solar energy devices, but also compact, power-efficient components for optical communication and increased performance in many other applications. The refractive index of natural materials only covers a limited range. Here, Chang et al. use the principle of space-filling curves to construct a mesoscopic crystal with a refractive index greater than 1000 at GHz frequencies. The concept is inherently broadband and scalable.
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Affiliation(s)
- Taeyong Chang
- Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Jong Uk Kim
- Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Seung Kyu Kang
- Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Hyowook Kim
- Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Do Kyung Kim
- Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Yong-Hee Lee
- Department of Physics, KAIST, Daejeon 34141, Republic of Korea
| | - Jonghwa Shin
- Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea
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Smaali R, Taliercio T, Centeno E. Photo-generated metasurfaces for resonant and high modulation of terahertz signals. OPTICS LETTERS 2016; 41:3900-3903. [PMID: 27519118 DOI: 10.1364/ol.41.003900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We theoretically demonstrate resonant modulation of terahertz (THz) waves with photo-designed metasurfaces. Our approach bypasses the short penetration length issue of the optical pump that prevents photo-generated thick metamaterials. We propose a three-layer semiconductor system of subwavelength thickness that presents 100% modulation of the reflection (or absorption) spectra at around 1 THz when optically actuated. This resonant modulation can be dynamically monitored at high frequency by the optical pump on a broad range of frequencies of Δν/ν=100%. Appropriate 2D photo-printed patterns make the system polarization insensitive and operational for a wide range of incident angles up to 65°.
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27
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On-chip sub-terahertz surface plasmon polariton transmission lines with mode converter in CMOS. Sci Rep 2016; 6:30063. [PMID: 27444782 PMCID: PMC4956764 DOI: 10.1038/srep30063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 06/27/2016] [Indexed: 11/09/2022] Open
Abstract
An on-chip low-loss and high conversion efficiency plasmonic waveguide converter is demonstrated at sub-THz in CMOS. By introducing a subwavelength periodic corrugated structure onto the transmission line (T-line) implemented by a top-layer metal, surface plasmon polaritons (SPP) are established to propagate signals with strongly localized surface-wave. To match both impedance and momentum of other on-chip components with TEM-wave propagation, a mode converter structure featured by a smooth bridge between the Ground coplanar waveguide (GCPW) with 50 Ω impedance and SPP T-line is proposed. To further reduce area, the converter is ultimately simplified to a gradual increment of groove with smooth gradient. The proposed SPP T-lines with the converter is designed and fabricated in the standard 65 nm CMOS process. Both near-field simulation and measurement results show excellent conversion efficiency from quasi-TEM to SPP modes in a broadband frequency range. The converter achieves wideband impedance matching (<-9 dB) with excellent transmission efficiency (averagely -1.9 dB) from 110 GHz-325 GHz. The demonstrated compact and wideband SPP T-lines with mode converter have shown great potentials to replace existing waveguides as future on-chip THz interconnects. To the best of the author's knowledge, this is the first time to demonstrate the (sub)-THz surface mode conversion on-chip in CMOS technology.
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28
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Kim SJ, Park J, Esfandyarpour M, Pecora EF, Kik PG, Brongersma ML. Superabsorbing, Artificial Metal Films Constructed from Semiconductor Nanoantennas. NANO LETTERS 2016; 16:3801-8. [PMID: 27149008 DOI: 10.1021/acs.nanolett.6b01198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In 1934, Wilhelm Woltersdorff demonstrated that the absorption of light in an ultrathin, freestanding film is fundamentally limited to 50%. He concluded that reaching this limit would require a film with a real-valued sheet resistance that is exactly equal to R = η/2 ≈ 188.5Ω/□, where [Formula: see text] is the impedance of free space. This condition can be closely approximated over a wide frequency range in metals that feature a large imaginary relative permittivity εr″, that is, a real-valued conductivity σ = ε0εr″ω. A thin, continuous sheet of semiconductor material does not facilitate such strong absorption as its complex-valued permittivity with both large real and imaginary components preclude effective impedance matching. In this work, we show how a semiconductor metafilm constructed from optically resonant semiconductor nanostructures can be created whose optical response mimics that of a metallic sheet. For this reason, the fundamental absorption limit mentioned above can also be reached with semiconductor materials, opening up new opportunities for the design of ultrathin optoelectronic and light harvesting devices.
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Affiliation(s)
- Soo Jin Kim
- Geballe Laboratory for Advanced Materials , 476 Lomita Mall, Stanford, California 94305-4045, United States
| | - Junghyun Park
- Geballe Laboratory for Advanced Materials , 476 Lomita Mall, Stanford, California 94305-4045, United States
| | - Majid Esfandyarpour
- Geballe Laboratory for Advanced Materials , 476 Lomita Mall, Stanford, California 94305-4045, United States
| | - Emanuele F Pecora
- Geballe Laboratory for Advanced Materials , 476 Lomita Mall, Stanford, California 94305-4045, United States
| | - Pieter G Kik
- Geballe Laboratory for Advanced Materials , 476 Lomita Mall, Stanford, California 94305-4045, United States
- CREOL, The College of Optics and Photonics, University of Central Florida , 4000 Central Florida Boulevard, Orlando, Florida 32816, United States
| | - Mark L Brongersma
- Geballe Laboratory for Advanced Materials , 476 Lomita Mall, Stanford, California 94305-4045, United States
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29
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Jafari M, Rais-Zadeh M. Zero-static-power phase-change optical modulator. OPTICS LETTERS 2016; 41:1177-1180. [PMID: 26977663 DOI: 10.1364/ol.41.001177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This Letter presents an innovative design of an electro-optical modulator using germanium telluride (GeTe) phase change material with an integrated nano-heater. The refractive index and the electrical conductivity of GeTe significantly change as the GeTe goes though the crystallographic phase change. Amorphization and crystallization of GeTe is achieved using the Joule heating method by passing current through an array of metal gratings, where GeTe fills the slits between the metal lines. These metal slits also increase the contrast between the amorphous (on) and crystalline (off) phases of the modulator by having extraordinary transmission and reflection response based on interactions of surface plasmon polaritons (SPPs) with the incoming light. The modulator is designed for 1550 nm wavelength, where GeTe is transparent in the amorphous phase and provides high optical on/off contrast. The metal-insulator-metal (MIM) is designed in such a way to only support SPP excitation when GeTe is crystalline and slit resonance when it is amorphous to increase the modulation index. The modulator is stable in both phases with higher than 12 dB change in transmission with zero static power consumption at room temperature.
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30
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Tang HH, Liu PK. Terahertz far-field superresolution imaging through spoof surface plasmons illumination. OPTICS LETTERS 2015; 40:5822-5825. [PMID: 26670521 DOI: 10.1364/ol.40.005822] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The applications of terahertz (THz) imaging are always restricted by the low resolution. We introduce here a new way to realize far-field superresolution imaging at THz frequency. Assisted by a new spoof surface plasmons (SSP) probe illumination, the images of two subwavelength separated slits can be reconstructed by a single shot. Although only 0.06λ resolution is numerically demonstrated at 0.3 THz, the resolution potentially can be further enhanced by scaling down the size of the SSP probe. Deep subwavelength focusing is also achieved by the SSP probe. Our work may open a new avenue for SSP-based superresolution at longer wavelengths.
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31
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Tan S, Yan F, Singh L, Cao W, Xu N, Hu X, Singh R, Wang M, Zhang W. Terahertz metasurfaces with a high refractive index enhanced by the strong nearest neighbor coupling. OPTICS EXPRESS 2015; 23:29222-29230. [PMID: 26561192 DOI: 10.1364/oe.23.029222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The realization of high refractive index is of significant interest in optical imaging with enhanced resolution. Strongly coupled subwavelength resonators were proposed and demonstrated at both optical and terahertz frequencies to enhance the refractive index due to large induced dipole moment in meta-atoms. Here, we report an alternative design for flexible free-standing terahertz metasurface in the strong coupling regime where we experimentally achieve a peak refractive index value of 14.36. We also investigate the impact of the nearest neighbor coupling in the form of frequency tuning and enhancement of the peak refractive index. We provide an analytical circuit model to explain the impact of geometrical parameters and coupling on the effective refractive index of the metasurface. The proposed meta-atom structure enables tailoring of the peak refractive index based on nearest neighbor coupling and this property offers tremendous design flexibility for transformation optics and other index-gradient devices at terahertz frequencies.
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On-chip sub-terahertz surface plasmon polariton transmission lines in CMOS. Sci Rep 2015; 5:14853. [PMID: 26445889 PMCID: PMC4597218 DOI: 10.1038/srep14853] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 08/06/2015] [Indexed: 11/10/2022] Open
Abstract
A low-loss and low-crosstalk surface-wave transmission line (T-line) is demonstrated at sub-THz in CMOS. By introducing periodical sub-wavelength structures onto the metal transmission line, surface plasmon polaritons (SPP) are excited and propagate signals via a strongly localized surface wave. Two coupled SPP T-lines and two quasi-TEM T-lines are both fabricated on-chip, each with a separation distance of 2.4 μm using standard 65 nm CMOS technology. Measurement results show that the SPP T-lines achieve wideband reflection coefficient lower than −14 dB and crosstalk ratio better than −24 dB, which is 19 dB lower on average than the traditional T-lines from 220 GHz to 325 GHz. The demonstrated compact and wideband SPP T-lines have shown great potential for future realization of highly dense on-chip sub-THz communications in CMOS.
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33
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Rupin M, Roux P, Lerosey G, Lemoult F. Symmetry issues in the hybridization of multi-mode waves with resonators: an example with Lamb waves metamaterial. Sci Rep 2015; 5:13714. [PMID: 26333601 PMCID: PMC4558541 DOI: 10.1038/srep13714] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 07/10/2015] [Indexed: 11/18/2022] Open
Abstract
Locally resonant metamaterials derive their effective properties from hybridization between their resonant unit cells and the incoming wave. This phenomenon is well understood in the case of plane waves that propagate in media where the unit cell respects the symmetry of the incident field. However, in many systems, several modes with orthogonal symmetries can coexist at a given frequency, while the resonant unit cells themselves can have asymmetric scattering cross-sections. In this paper we are interested in the influence of symmetry breaking on the hybridization of a wave field that includes multiple propagative modes. The A0 and S0 Lamb waves that propagate in a thin plate are good candidates for this study, as they are either anti-symmetric or symmetric. First we designed an experimental setup with an asymmetric metamaterial made of long rods glued to one side of a metallic plate. We show that the flexural resonances of the rods induce a break of the orthogonality between the A0/S0 modes of the free-plate. Finally, based on numerical simulations we show that the orthogonality is preserved in the case of a symmetric metamaterial leading to the presence of two independent polariton curves in the dispersion relation.
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Affiliation(s)
- Matthieu Rupin
- Institut Langevin, ESPCI ParisTech and CNRS UMR 7587, PSL Research University, 1 rue Jussieu, 75005, Paris, France
| | - Philippe Roux
- Institut des Sciences de la Terre, UMR 5275, Université Joseph Fourier, Grenoble, 38000, France
| | - Geoffroy Lerosey
- Institut Langevin, ESPCI ParisTech and CNRS UMR 7587, PSL Research University, 1 rue Jussieu, 75005, Paris, France
| | - Fabrice Lemoult
- Institut Langevin, ESPCI ParisTech and CNRS UMR 7587, PSL Research University, 1 rue Jussieu, 75005, Paris, France
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Naserpour M, Zapata-Rodríguez CJ, Díaz-Aviñó C, Hashemi M, Miret JJ. Ultrathin high-index metasurfaces for shaping focused beams. APPLIED OPTICS 2015; 54:7586-7591. [PMID: 26368881 DOI: 10.1364/ao.54.007586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The volume size of a converging wave, which plays a relevant role in image resolution, is governed by the wavelength of the radiation and the numerical aperture (NA) of the wavefront. We designed an ultrathin (λ/8 width) curved metasurface that is able to transform a focused field into a high-NA optical architecture, thus boosting the transverse and (mainly) on-axis resolution. The elements of the metasurface are metal-insulator subwavelength gratings exhibiting extreme anisotropy with ultrahigh index of refraction for TM polarization. Our results can be applied to nanolithography and optical microscopy.
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35
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Vasilantonakis N, Nasir ME, Dickson W, Wurtz GA, Zayats AV. Bulk plasmon-polaritons in hyperbolic nanorod metamaterial waveguides. LASER & PHOTONICS REVIEWS 2015; 9:345-353. [PMID: 26693254 PMCID: PMC4676384 DOI: 10.1002/lpor.201400457] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 02/24/2015] [Accepted: 03/12/2015] [Indexed: 05/21/2023]
Abstract
Hyperbolic metamaterials comprised of an array of plasmonic nanorods provide a unique platform for designing optical sensors and integrating nonlinear and active nanophotonic functionalities. In this work, the waveguiding properties and mode structure of planar anisotropic metamaterial waveguides are characterized experimentally and theoretically. While ordinary modes are the typical guided modes of the highly anisotropic waveguides, extraordinary modes, below the effective plasma frequency, exist in a hyperbolic metamaterial slab in the form of bulk plasmon-polaritons, in analogy to planar-cavity exciton-polaritons in semiconductors. They may have very low or negative group velocity with high effective refractive indices (up to 10) and have an unusual cut-off from the high-frequency side, providing deep-subwavelength (λ0/6-λ0/8 waveguide thickness) single-mode guiding. These properties, dictated by the hyperbolic anisotropy of the metamaterial, may be tuned by altering the geometrical parameters of the nanorod composite.
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Affiliation(s)
- Nikolaos Vasilantonakis
- Department of Physics, King's College LondonStrand, London, WC2R 2LS, UK
- * Corresponding author: e-mail:
| | - Mazhar E Nasir
- Department of Physics, King's College LondonStrand, London, WC2R 2LS, UK
| | - Wayne Dickson
- Department of Physics, King's College LondonStrand, London, WC2R 2LS, UK
| | - Gregory A Wurtz
- Department of Physics, King's College LondonStrand, London, WC2R 2LS, UK
| | - Anatoly V Zayats
- Department of Physics, King's College LondonStrand, London, WC2R 2LS, UK
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36
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High-order localized spoof surface plasmon resonances and experimental verifications. Sci Rep 2015; 5:9590. [PMID: 25873523 PMCID: PMC4397533 DOI: 10.1038/srep09590] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/12/2015] [Indexed: 11/08/2022] Open
Abstract
We theoretically demonstrated and experimentally verified high-order radial spoof localized surface plasmon resonances supported by textured metal particles. Through an effective medium theory and exact numerical simulations, we show the emergence of these geometrically-originated electromagnetic modes at microwave frequencies. The occurrence of high-order radial spoof plasmon resonances is experimentally verified in ultrathin disks. Their spectral and near-field properties are characterized experimentally, showing an excellent agreement with theoretical predictions. Our findings shed light into the nature of spoof localized surface plasmons, and open the way to the design of broadband plasmonic devices able to operate at very different frequency regimes.
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37
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Sadeghi MM, Li S, Xu L, Hou B, Chen H. Transformation optics with Fabry-Pérot resonances. Sci Rep 2015; 5:8680. [PMID: 25726924 PMCID: PMC4345524 DOI: 10.1038/srep08680] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 01/12/2015] [Indexed: 11/22/2022] Open
Abstract
Transformation optics is a powerful tool to design various novel devices, such as invisibility cloak. Fantastic effects from this technique are usually accompanied with singular mappings, resulting in challenging implementations and narrow bands of working frequencies. Here in this article, Fabry-Pérot resonances in materials of extreme anisotropy are used to design various transformation optical devices that are not only easy to realize but also work well for a set of resonant frequencies (multiple frequencies). As an example, a prototype of a cylindrical concentrator is fabricated for microwaves.
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Affiliation(s)
- M M Sadeghi
- College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China
| | - Sucheng Li
- College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China
| | - Lin Xu
- College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China
| | - Bo Hou
- College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China
| | - Huanyang Chen
- College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China
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38
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Experimental realization of photonic topological insulator in a uniaxial metacrystal waveguide. Nat Commun 2014; 5:5782. [PMID: 25517229 DOI: 10.1038/ncomms6782] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 11/07/2014] [Indexed: 11/08/2022] Open
Abstract
Photonic analogue of topological insulator was recently predicted by arranging ε/μ (permittivity/permeability)-matched bianisotropic metamaterials into two-dimensional superlattices. However, the experimental observation of such photonic topological insulator is challenging as bianisotropic metamaterial is usually highly dispersive, so that the ε/μ-matching condition can only be satisfied in a narrow frequency range. Here we experimentally realize a photonic topological insulator by embedding non-bianisotropic and non-resonant metacrystal into a waveguide. The cross coupling between transverse electric and transverse magnetic modes exists in metacrystal waveguide. Using this approach, the ε/μ-matching condition is satisfied in a broad frequency range which facilitates experimental observation. The topologically non-trivial bandgap is confirmed by experimentally measured transmission spectra and calculated non-zero spin Chern numbers. Gapless spin-filtered edge states are demonstrated experimentally by measuring the magnitude and phase of the fields. The transport robustness of the edge states is also observed when an obstacle was introduced near the edge.
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39
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Zharov AA, Zharov AA, Zharova NA. Spontaneous reorientations of meta-atoms and electromagnetic spatial solitons in a liquid metacrystal. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:023207. [PMID: 25215843 DOI: 10.1103/physreve.90.023207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Indexed: 06/03/2023]
Abstract
We show that transverse electromagnetic waves propagating along an external static electric field in liquid metacrystal (LMC) can provoke spontaneous rearrangement of elongated meta-atoms that changes the direction of the anisotropy axis of the LMC. This kind of instability may reorient the meta-atoms from the equilibrium state parallel to a static field to the state along a high-frequency field and back at the different threshold intensities of electromagnetic waves in such a way that bistability in the system takes place. Reorientation of meta-atoms causes a change in the effective refraction index of LMC that creates, in turn, the conditions for the formation of bright spatial solitons. Such spatial solitons are the self-consistent domains of redirected meta-atoms with trapped photons. We find that the instability thresholds as well as energy flux captured by the spatial soliton can be easily managed by variation of the static electric field applied to the LMC. We study the effects of soliton excitation and collisions via numerical simulations.
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Affiliation(s)
- Alexander A Zharov
- Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhny Novgorod, 603950 Russia and N.I. Lobachevsky State University, Nizhny Novgorod, 603950 Russia
| | - Alexander A Zharov
- Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhny Novgorod, 603950 Russia and N.I. Lobachevsky State University, Nizhny Novgorod, 603950 Russia
| | - Nina A Zharova
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, 603950 Russia
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40
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Colombi A, Roux P, Rupin M. Sub-wavelength energy trapping of elastic waves in a metamaterial. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2014; 136:EL192-EL198. [PMID: 25096146 DOI: 10.1121/1.4890942] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Deep sub-wavelength focusing has been demonstrated for locally resonant metamaterials using electromagnetic and acoustic waves. The elastic equivalents of such objects are made of sub-wavelength resonating beams fixed to a two-dimensional plate, as presented here. Independent of a random or regular arrangement of the resonators, the metamaterial shows large bandgaps that are independent of the incident wave direction. Numerical simulations demonstrate that the insertion of a defect in the layout, as a shorter resonator, creates strong amplification of the wave-field on the defect. This energy trapping, which is localized on a spatial scale that is much smaller than the wavelength in the two-dimensional plate, leads to a >1 factor in terms of the local density of energy.
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Affiliation(s)
- Andrea Colombi
- ISTerre, Université Joseph Fourier, Grenoble, BP 53 38041, Grenoble CEDEX 9, France , ,
| | - Philippe Roux
- ISTerre, Université Joseph Fourier, Grenoble, BP 53 38041, Grenoble CEDEX 9, France , ,
| | - Matthieu Rupin
- ISTerre, Université Joseph Fourier, Grenoble, BP 53 38041, Grenoble CEDEX 9, France , ,
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41
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Akarid A, Ourir A, Maurel A, Félix S, Mercier JF. Extraordinary transmission through subwavelength dielectric gratings in the microwave range. OPTICS LETTERS 2014; 39:3752-3755. [PMID: 24978728 DOI: 10.1364/ol.39.003752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We address the problem of the transmission through subwavelength dielectric gratings. Following Maurel et al. [Phys. Rev. B 88, 115416 (2013)], the problem is reduced to the transmission by an homogeneous slab, either anisotropic (for transverse magnetic waves, TM) or isotropic (for transverse electric waves, TE), and an explicit expression of the transmission coefficient is derived. The optimum angle realizing perfect impedance matching (Brewster angle) is shown to depend on the contrasts of the dielectric layers with respect to the air. Besides, we show that the Fabry-Perot resonances may be dependent on the incident angle, in addition to the dependence on the frequency. These facts depart from the case of metallic gratings usually considered; they are confirmed experimentally both for TE and TM waves in the microwave regime.
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42
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Rupin M, Lemoult F, Lerosey G, Roux P. Experimental demonstration of ordered and disordered multiresonant metamaterials for lamb waves. PHYSICAL REVIEW LETTERS 2014; 112:234301. [PMID: 24972210 DOI: 10.1103/physrevlett.112.234301] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Indexed: 06/03/2023]
Abstract
We demonstrate the experimental realization of a multiresonant metamaterial for Lamb waves, i.e., elastic waves propagating in plates. The metamaterial effect comes from the resonances of long aluminum rods that are attached to an aluminum plate. Using time-dependent measurements, we experimentally prove that this metamaterial exhibits wide band gaps as well as sub- and suprawavelength modes for both a periodic and a random arrangement of the resonators. The dispersion curve inside the metamaterial is predicted through hybridizations between flexural and compressional resonances in the rods and slow and fast Lamb modes in the plate. We finally underline how the various degrees of freedom of such system paves the way to the design of metamaterials for the control of Lamb waves in unprecedented ways.
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Affiliation(s)
- Matthieu Rupin
- Institut des Sciences de la Terre, UMR 5275, Université Joseph Fourier, 38000 Grenoble, France
| | - Fabrice Lemoult
- Institut Langevin, ESPCI ParisTech and CNRS UMR 7587, PSL Research University, 1 rue Jussieu, 75005, Paris, France
| | - Geoffroy Lerosey
- Institut Langevin, ESPCI ParisTech and CNRS UMR 7587, PSL Research University, 1 rue Jussieu, 75005, Paris, France
| | - Philippe Roux
- Institut des Sciences de la Terre, UMR 5275, Université Joseph Fourier, 38000 Grenoble, France
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43
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Realization of deep subwavelength resolution with singular media. Sci Rep 2014; 4:5212. [PMID: 24909738 PMCID: PMC4048882 DOI: 10.1038/srep05212] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 05/07/2014] [Indexed: 11/09/2022] Open
Abstract
The record of imaging resolution has kept being refreshed in the past decades and the best resolution of hyperlenses and superlenses so far is about one out of tens in terms of wavelength. In this paper, by adopting a hybrid concept of transformation optics and singular media, we report a broadband meta-lens design methodology with ultra-high resolution. The meta-lens is made of subwavelength metal/air layers, which exhibit singular medium property over a broad band. As a proof of concept, the subwavelength imaging ability is demonstrated over a broad frequency band from 1.5-10 GHz with the resolution varying from 1/117 to 1/17 wavelength experimentally.
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44
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Kim KJ, Kim JE, Park HY, Lee YH, Kim SH, Lee SG, Kee CS. Propagation of spoof surface plasmon on metallic square lattice: bending and splitting of self-collimated beams. OPTICS EXPRESS 2014; 22:4050-4058. [PMID: 24663726 DOI: 10.1364/oe.22.004050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The propagation characteristics of spoof surface plasmon modes are studied in both real and reciprocal spaces. From the metallic square lattice, we obtain constant frequency contours by directly measuring electric fields in the microwave frequency regime. The anisotropy of the measured constant frequency contour supports the presence of the negative refraction and the self-collimation which are confirmed from measured electric fields. Additionally, we demonstrate the spoof surface plasmon beam splitter in which the splitting ratio of the self-collimated beam is controlled by varying the height of rods.
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45
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Bera A, Barik RK, Sattorov M, Kwon O, Min SH, Baek IK, Kim S, So JK, Park GS. Surface-coupling of Cerenkov radiation from a modified metallic metamaterial slab via Brillouin-band folding. OPTICS EXPRESS 2014; 22:3039-3044. [PMID: 24663594 DOI: 10.1364/oe.22.003039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Metallic metamaterials with positive dielectric responses are promising as an alternative to dielectrics for the generation of Cerenkov radiation [J.-K. So et al., Appl. Phys. Lett. 97(15), 151107 (2010)]. We propose here by theoretical analysis a mechanism to couple out Cerenkov radiation from the slab surfaces in the transverse direction. The proposed method based on Brillouin-zone folding is to periodically modify the thickness of the metamaterial slab in the axial direction. Moreover, the intensity of the surface-coupled radiation by this mechanism shows an order-of-magnitude enhancement compared to that of ordinary Smith-Purcell radiation.
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46
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Zhou J, Guo LJ. Transition from a spectrum filter to a polarizer in a metallic nano-slit array. Sci Rep 2014; 4:3614. [PMID: 24402443 PMCID: PMC3885878 DOI: 10.1038/srep03614] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 11/29/2013] [Indexed: 11/09/2022] Open
Abstract
The transition from a spectrum filter (resonant transmission) to a polarizer (broadband transmission) for TM polarized light is observed in a metallic nano-slit array as period is decreased. A theoretical model is developed and shows that the spectrum filter behavior is caused by the coupled slit/grating resonance. With decreasing period, the slit resonance is decoupled from the grating resonance, which then dominates the transmission spectrum and broadens the transmission peak. With further reducing period, the slit resonance diminishes and the peak spectrum transforms to a broadband transmission. This effect is the basis for the operation of wire grid polarizers. The transition is explained by the change of the impedance to the incoming wave.
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Affiliation(s)
- Jing Zhou
- Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, Michigan 48109, USA
| | - L Jay Guo
- Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, Michigan 48109, USA
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47
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Hooper IR, Philbin TG. Transmutation of singularities and zeros in graded index optical instruments: a methodology for designing practical devices. OPTICS EXPRESS 2013; 21:32313-32326. [PMID: 24514824 DOI: 10.1364/oe.21.032313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We describe a design methodology for modifying the refractive index profile of graded-index optical instruments that incorporate singularities or zeros in their refractive index. The process maintains the device performance whilst resulting in graded profiles that are all-dielectric, do not require materials with unrealistic values, and that are impedance matched to the bounding medium. This is achieved by transmuting the singularities (or zeros) using the formalism of transformation optics, but with an additional boundary condition requiring the gradient of the co-ordinate transformation be continuous. This additional boundary condition ensures that the device is impedance matched to the bounding medium when the spatially varying permittivity and permeability profiles are scaled to realizable values. We demonstrate the method in some detail for an Eaton lens, before describing the profiles for an "invisible disc" and "multipole" lenses.
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48
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Kaina N, Fink M, Lerosey G. Composite media mixing Bragg and local resonances for highly attenuating and broad bandgaps. Sci Rep 2013; 3:3240. [PMID: 24247617 PMCID: PMC3832873 DOI: 10.1038/srep03240] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 10/29/2013] [Indexed: 11/19/2022] Open
Abstract
In this article, we investigate composite media which present both a local resonance and a periodic structure. We numerically and experimentally consider the case of a very academic and simplified system that is a quasi-one dimensional split ring resonator medium. We modify its periodicity to shift the position of the Bragg bandgap relative to the local resonance one. We observe that for a well-chosen lattice constant, the local resonance frequency matches the Bragg frequency thus opening a single bandgap which is at the same time very wide and strongly attenuating. We explain this interesting phenomenon by the dispersive nature of the unit cell of the medium, using an analogy with the concept of white light cavities. Our results provide new ways to design wide and efficient bandgap materials.
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Affiliation(s)
- Nadège Kaina
- Institut Langevin, ESPCI ParisTech & CNRS UMR 7587, 1 rue Jussieu, 75005 Paris, France
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49
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Guo L, Marthaler M, Schön G. Phase space crystals: a new way to create a quasienergy band structure. PHYSICAL REVIEW LETTERS 2013; 111:205303. [PMID: 24289695 DOI: 10.1103/physrevlett.111.205303] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Indexed: 06/02/2023]
Abstract
A novel way to create a band structure of the quasienergy spectrum for driven systems is proposed based on the discrete symmetry in phase space. The system, e.g., an ion or ultracold atom trapped in a potential, shows no spatial periodicity, but it is driven by a time-dependent field coupling highly nonlinearly to one of its degrees of freedom (e.g., ∼q(n)). The band structure in quasienergy arises as a consequence of the n-fold discrete periodicity in phase space induced by this driving field. We propose an explicit model to realize such a phase space crystal and analyze its band structure in the frame of a tight-binding approximation. The phase space crystal opens new ways to engineer energy band structures, with the added advantage that its properties can be changed in situ by tuning the driving field's parameters.
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Affiliation(s)
- Lingzhen Guo
- Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany and Department of Physics, Beijing Normal University, Beijing 100875, China and DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany
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50
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Luk TS, Kim I, Campione S, Howell SW, Subramania GS, Grubbs RK, Brener I, Chen HT, Fan S, Sinclair MB. Near-infrared surface plasmon polariton dispersion control with hyperbolic metamaterials. OPTICS EXPRESS 2013; 21:11107-11114. [PMID: 23669967 DOI: 10.1364/oe.21.011107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We demonstrate experimentally signatures and dispersion control of surface plasmon polaritons from 1 to 1.8 µm using periodic multilayer metallo-dielectric hyperbolic metamaterials. The fabricated structures are comprised of smooth films with very low metal filling factor. The measured dispersion properties of these hyperbolic metamaterials agree well with calculations using transfer matrix, finite-difference time-domain, and effective medium approximation methods despite using only 2.5 periods. The enhancement factor in the local photonic density of states from the studied samples in the near-infrared wavelength region is determined to be 2.5-3.5. Development of this type of metamaterial is relevant to sub-wavelength imaging, spontaneous emission and thermophotovoltaic applications.
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Affiliation(s)
- Ting S Luk
- Sandia National Laboratories, 1515 Eubank SE, Albuquerque, NM 87123, USA.
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