The Experts below are selected from a list of 98499 Experts worldwide ranked by ideXlab platform
Geoffroy Lerosey - One of the best experts on this subject based on the ideXlab platform.
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negative refractive index and acoustic superlens from multiple scattering in single negative Metamaterials
Nature, 2015Co-Authors: Nadege Kaina, Fabrice Lemoult, Mathias Fink, Geoffroy LeroseyAbstract:A negative refractive index, a property that does not exist in natural materials, can be produced in so-called Metamaterials by combining two building blocks; here it is shown that it is possible to design and fabricate a metamaterial with a negative refractive index that consists of only one type of building block by taking advantage of its crystalline structure, and this approach is demonstrated through an acoustic superlens. Negative refractive index, a property that doesn't exist in nature, can be produced in Metamaterials that have simultaneous negative permittivity and negative permeability. This is normally achieved by combining two different building blocks. However, Nadege Kaina et al. now show that it is possible to design and fabricate media with a negative refractive index that consist of only one type of building block. In such a 'single negative' metamaterial, multiple scattering of waves leads to 'double negative' properties. The approach is demonstrated for acoustics, and the authors show that it is possible to make an acoustic metamaterial with superlensing properties, the hallmark of a negative refractive index. The method could open up a simpler way of designing and constructing Metamaterials with interesting properties. Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves1,2,3,4,5,6. One of the most interesting of these is the ability to achieve superlensing—that is, to focus or image beyond the diffraction limit7. This originates from the left-handed behaviour—the property of refracting waves negatively—that is typical of negative index Metamaterials8,9,10. Yet reaching this goal requires the design of ‘double negative’ Metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics11,12, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks13,14 or specific particles presenting multiple overlapping resonances15,16,17. Such a requirement limits the applicability of double negative Metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic Metamaterials18. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic Metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the physics of Metamaterials, highlighting the role of their subwavelength crystalline structure, and hence entering the realm of metamaterial crystals. This widens the scope of possibilities for designing composite media with novel properties in a much simpler way than has been possible so far.
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negative refractive index and acoustic superlens from multiple scattering in single negative Metamaterials
Nature, 2015Co-Authors: Nadege Kaina, Fabrice Lemoult, Mathias Fink, Geoffroy LeroseyAbstract:Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves. One of the most interesting of these is the ability to achieve superlensing--that is, to focus or image beyond the diffraction limit. This originates from the left-handed behavior--the property of refracting waves negatively--that is typical of negative index Metamaterials. Yet reaching this goal requires the design of 'double negative' Metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks or specific particles presenting multiple overlapping resonances. Such a requirement limits the applicability of double negative Metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic Metamaterials. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic Metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the physics of Metamaterials, highlighting the role of their subwavelength crystalline structure, and hence entering the realm of metamaterial crystals. This widens the scope of possibilities for designing composite media with novel properties in a much simpler way than has been possible so far.
N I Zheludev - One of the best experts on this subject based on the ideXlab platform.
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Nano-optomechanical Metamaterials
2018Co-Authors: Dimitrios Papas, Eric Plum, Artemios Karvounis, N I ZheludevAbstract:The development of Metamaterials has led to demonstrations of fascinating optical properties such as negative refraction, invisibility, ultra-thin lenses and many more. However, the unique properties of Metamaterials are usually fixed and narrowband. Here we develop nano-optomechanical Metamaterials that offer a flexible platform for static and fast dynamic control of metamaterial optical properties using electrostatic, magnetic, optical forces and ultrasound.
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an electromechanically reconfigurable plasmonic metamaterial operating in the near infrared
Nature Nanotechnology, 2013Co-Authors: Junyu Ou, Eric Plum, Jianfa Zhang, N I ZheludevAbstract:Current efforts in Metamaterials research focus on dynamic functionalities such as tunability, switching and modulation of electromagnetic waves. To this end, various approaches have appeared, including embedded varactors, phase-change media, use of liquid crystals, electrical modulation with graphene and superconductors, and carrier injection or depletion in semiconductor substrates. However, tuning, switching and modulating metamaterial properties in the visible and near-infrared range remain major technological challenges: the existing microelectromechanical solutions for the subTHz and THz regimes cannot be shrunk by 2-3 orders of magnitude to enter the optical spectral range. Here we develop a new type of metamaterial operating in the optical part of the spectrum which is 3 orders of magnitude faster than previously reported electrically reconfigurable Metamaterials. The metamaterial is actuated by electrostatic forces arising from the application of only a few volts to its nanoscale building blocks, the plasmonic metamolecules, which are supported by pairs of parallel strings cut from a nanoscale thickness flexible silicon nitride membrane. These strings of picogram mass can be synchronously driven to megahertz frequencies to electromechanically reconfigure the metamolecules and dramatically change the metamaterial’s transmission and reflection spectra. The metamaterial’s colossal electro-optical response allows for both fast continuous tuning of its optical properties (up to 8% optical signal modulation at up to megahertz rates) and high-contrast irreversible switching in a device of only 100 nm thickness without the need for external polarizers and analyzers.
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An electromechanically reconfigurable plasmonic metamaterial operating in the near-infrared
Nature Nanotechnology, 2013Co-Authors: Junyu Ou, Eric Plum, Jianfa Zhang, N I ZheludevAbstract:Current efforts in Metamaterials research focus on attaining dynamic functionalities such as tunability, switching and modulation of electromagnetic waves^ 1 . To this end, various approaches have emerged, including embedded varactors^ 2 , phase-change media^ 3 , 4 , the use of liquid crystals^ 5 , 6 , electrical modulation with graphene^ 7 , 8 and superconductors^ 9 , and carrier injection or depletion in semiconductor substrates^ 10 , 11 . However, tuning, switching and modulating metamaterial properties in the visible and near-infrared range remain major technological challenges: indeed, the existing microelectromechanical solutions used for the sub-terahertz^ 12 and terahertz^ 13 , 14 , 15 regimes cannot be shrunk by two to three orders of magnitude to enter the optical spectral range. Here, we develop a new type of metamaterial operating in the optical part of the spectrum that is three orders of magnitude faster than previously reported electrically reconfigurable Metamaterials. The metamaterial is actuated by electrostatic forces arising from the application of only a few volts to its nanoscale building blocks—the plasmonic metamolecules—that are supported by pairs of parallel strings cut from a flexible silicon nitride membrane of nanoscale thickness. These strings, of picogram mass, can be driven synchronously to megahertz frequencies to electromechanically reconfigure the metamolecules and dramatically change the transmission and reflection spectra of the metamaterial. The metamaterial's colossal electro-optical response (on the order of 10^−5–10^−6 m V^−1) allows for either fast continuous tuning of its optical properties (up to 8% optical signal modulation at up to megahertz rates) or high-contrast irreversible switching in a device only 100 nm thick, without the need for external polarizers and analysers. Electrostatic forces drive mechanical reconfiguration of a photonic metamaterial and enable megahertz-frequency electric modulation of its optical properties.
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Reconfiguring photonic Metamaterials
2012Co-Authors: Eric Plum, Jianfa Zhang, João Valente, N I ZheludevAbstract:Dynamic control over metamaterial optical properties is key for the use of Metamaterials as active elements ranging from modulators and switches to tunable filters and programmable transformation optics devices. Here we exploit that the properties of virtually any metamaterial structure strongly depend on the spatial arrangement of its components. By manufacturing plasmonic Metamaterials on a grid of elastic dielectric bridges of nanoscale thickness, we are able to dynamically rearrange sub-micron sized plasmonic building blocks across the entire metamaterial array (see figure). We demonstrate that this approach provides a flexible platform for continuous tuning, fast modulation and high-contrast switching of photonic Metamaterials via external stimuli such as electric voltages, optical excitation and magnetic fields.
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Micromachined tunable Metamaterials: a review
Journal of Optics, 2012Co-Authors: Ai Qun Liu, Weiming Zhu, Din Ping Tsai, N I ZheludevAbstract:This paper reviews micromachined tunable Metamaterials, whereby the tuning capabilities are based on the mechanical reconfiguration of the lattice and/or the metamaterial element geometry. The primary focus of this review is the feasibility of the realization of micromachined tunable Metamaterials via structure reconfiguration and the current state of the art in the fabrication technologies of structurally reconfigurable metamaterial elements. The micromachined reconfigurable microstructures not only offer a new tuning method for Metamaterials without being limited by the nonlinearity of constituent materials, but also enable a new paradigm of reconfigurable metamaterial-based devices with mechanical actuations. With recent development in nanomachining technology, it is possible to develop structurally reconfigurable Metamaterials with faster tuning speed, higher density of integration and more flexible choice of the working frequencies.
Nadege Kaina - One of the best experts on this subject based on the ideXlab platform.
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negative refractive index and acoustic superlens from multiple scattering in single negative Metamaterials
Nature, 2015Co-Authors: Nadege Kaina, Fabrice Lemoult, Mathias Fink, Geoffroy LeroseyAbstract:A negative refractive index, a property that does not exist in natural materials, can be produced in so-called Metamaterials by combining two building blocks; here it is shown that it is possible to design and fabricate a metamaterial with a negative refractive index that consists of only one type of building block by taking advantage of its crystalline structure, and this approach is demonstrated through an acoustic superlens. Negative refractive index, a property that doesn't exist in nature, can be produced in Metamaterials that have simultaneous negative permittivity and negative permeability. This is normally achieved by combining two different building blocks. However, Nadege Kaina et al. now show that it is possible to design and fabricate media with a negative refractive index that consist of only one type of building block. In such a 'single negative' metamaterial, multiple scattering of waves leads to 'double negative' properties. The approach is demonstrated for acoustics, and the authors show that it is possible to make an acoustic metamaterial with superlensing properties, the hallmark of a negative refractive index. The method could open up a simpler way of designing and constructing Metamaterials with interesting properties. Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves1,2,3,4,5,6. One of the most interesting of these is the ability to achieve superlensing—that is, to focus or image beyond the diffraction limit7. This originates from the left-handed behaviour—the property of refracting waves negatively—that is typical of negative index Metamaterials8,9,10. Yet reaching this goal requires the design of ‘double negative’ Metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics11,12, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks13,14 or specific particles presenting multiple overlapping resonances15,16,17. Such a requirement limits the applicability of double negative Metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic Metamaterials18. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic Metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the physics of Metamaterials, highlighting the role of their subwavelength crystalline structure, and hence entering the realm of metamaterial crystals. This widens the scope of possibilities for designing composite media with novel properties in a much simpler way than has been possible so far.
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negative refractive index and acoustic superlens from multiple scattering in single negative Metamaterials
Nature, 2015Co-Authors: Nadege Kaina, Fabrice Lemoult, Mathias Fink, Geoffroy LeroseyAbstract:Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves. One of the most interesting of these is the ability to achieve superlensing--that is, to focus or image beyond the diffraction limit. This originates from the left-handed behavior--the property of refracting waves negatively--that is typical of negative index Metamaterials. Yet reaching this goal requires the design of 'double negative' Metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks or specific particles presenting multiple overlapping resonances. Such a requirement limits the applicability of double negative Metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic Metamaterials. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic Metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the physics of Metamaterials, highlighting the role of their subwavelength crystalline structure, and hence entering the realm of metamaterial crystals. This widens the scope of possibilities for designing composite media with novel properties in a much simpler way than has been possible so far.
Xiaoming Zhou - One of the best experts on this subject based on the ideXlab platform.
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acoustic Metamaterials capable of both sound insulation and energy harvesting
Smart Materials and Structures, 2016Co-Authors: Junfei Li, Xiaoming Zhou, G L Huang, Gengkai HuAbstract:Membrane-type acoustic Metamaterials are well known for low-frequency sound insulation. In this work, by introducing a flexible piezoelectric patch, we propose sound-insulation Metamaterials with the ability of energy harvesting from sound waves. The dual functionality of the metamaterial device has been verified by experimental results, which show an over 20 dB sound transmission loss and a maximum energy conversion efficiency up to 15.3% simultaneously. This novel property makes the metamaterial device more suitable for noise control applications.
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Subwavelength acoustic focusing by surface-wave-resonance enhanced transmission in doubly negative acoustic Metamaterials
Journal of Applied Physics, 2014Co-Authors: Xiaoming Zhou, M. Badreddine Assouar, Mourad OudichAbstract:We present analytical and numerical analyses of a yet unseen lensing paradigm that is based on a solid metamaterial slab in which the wave excitation source is attached. We propose and demonstrate sub-diffraction-limited acoustic focusing induced by surface resonant states in doubly negative Metamaterials. The enhancement of evanescent waves across the metamaterial slab produced by their resonant coupling to surface waves is evidenced and quantitatively determined. The effect of metamaterial parameters on surface states, transmission, and wavenumber bandwidth is clearly identified. Based on this concept consisting of a wave source attached on the metamaterial, a high resolution of lambda/28.4 is obtained with the optimum effective physical parameters, opening then an exciting way to design acoustic Metamaterials for ultrasonic focused imaging.
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Thin-plate Metamaterials: physics and applications
Proceedings of SPIE, 2012Co-Authors: Pei Li, Xiaoming Zhou, Guoliang Huang, Gengkai HuAbstract:A thin-plate metamaterial made of a thin plate periodically attached with mass-spring oscillators is analyzed. Based on the analytic solutions of sound waves incident on the metamaterial, effective mass density can be defined. Approximate expressions of effective mass can be derived when the first-order vibration mode of the plate is considered. It is found that the Lorentz and Drude behavior of effective mass can be obtained. As an example of potential applications, the sound insulation effects of multilayered thin-plate Metamaterials are studied. High transmission loss can be achieved in a finite-layered Metamaterials at negative-mass frequencies. Their applications to noise control can be anticipated.
Mourad Oudich - One of the best experts on this subject based on the ideXlab platform.
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Subwavelength acoustic focusing by surface-wave-resonance enhanced transmission in doubly negative acoustic Metamaterials
Journal of Applied Physics, 2014Co-Authors: Xiaoming Zhou, M. Badreddine Assouar, Mourad OudichAbstract:We present analytical and numerical analyses of a yet unseen lensing paradigm that is based on a solid metamaterial slab in which the wave excitation source is attached. We propose and demonstrate sub-diffraction-limited acoustic focusing induced by surface resonant states in doubly negative Metamaterials. The enhancement of evanescent waves across the metamaterial slab produced by their resonant coupling to surface waves is evidenced and quantitatively determined. The effect of metamaterial parameters on surface states, transmission, and wavenumber bandwidth is clearly identified. Based on this concept consisting of a wave source attached on the metamaterial, a high resolution of lambda/28.4 is obtained with the optimum effective physical parameters, opening then an exciting way to design acoustic Metamaterials for ultrasonic focused imaging.
