A holey-structured metamaterial for acoustic deep-subwavelength imaging

Zhu, Jie; Christensen, Johan; Jung, Jesper; Martín‐Moreno, Luis; Yin, Xiaobo; Fok, Lee; Zhang, Xiang; García‐Vidal, F. J.

doi:10.1038/nphys1804

Cited by 578 publications

(395 citation statements)

References 36 publications

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“…This kind of anisotropic acoustic metamaterial was later utilized in the fabrication of a 3D holey-structured metamaterial for acoustic deep-subwavelength imaging 89 . A 2D object with a line width of 3.18 mm can be clearly resolved at the operating frequency of 2.18 kHz, demonstrating a subwavelength resolution of l/50 (ref.…”

Section: Extraordinary Imaging Properties Of the Hyperbolic Metalensmentioning

confidence: 99%

“…A 2D object with a line width of 3.18 mm can be clearly resolved at the operating frequency of 2.18 kHz, demonstrating a subwavelength resolution of l/50 (ref. 89). This was achieved by the effective transmission of evanescent wave components carrying deep-subwavelength details to the output side through the Fabry-Pérot resonances excited inside the holey structure.…”

Section: Extraordinary Imaging Properties Of the Hyperbolic Metalensmentioning

confidence: 99%

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Hyperlenses and metalenses for far-field super-resolution imaging

2012

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The resolution of conventional optical lens systems is always hampered by the diffraction limit. Recent developments in artificial metamaterials provide new avenues to build hyperlenses and metalenses that are able to image beyond the diffraction limit. Hyperlenses project super-resolution information to the far field through a magnification mechanism, whereas metalenses not only super-resolve subwavelength details but also enable optical Fourier transforms. Recently, there have been numerous designs for hyperlenses and metalenses, bringing fresh theoretical and experimental advances, though future directions and challenges remain to be overcome.O ptical microscopy has revolutionized many fields such as microelectronics, biology and medicine. However, the resolution of a conventional optical lens system is always limited by diffraction to about half the wavelength of light. This diffraction barrier arises from the fact that subwavelength information from an object is carried by high spatial-frequency evanescent waves, which only exist in the near field. To overcome this diffraction limit, pioneering work has been carried out, including near-field scanning microscopy 1 , as well as fluorescence-based imaging methods 2,3 . These scanning-or random sampling-based nonprojection techniques achieve super-resolving power by sacrificing imaging speed, making them uncompetitive for dynamic imaging.Lens-based projection imaging remains the best option for high-speed microscopy. Immersion techniques have been proposed to enhance resolution, but they are limited by the low refractive indices of natural materials 4 . Emerging within the last decade, the fields of plasmonics and metamaterials provide solutions for engineering extraordinary material properties not found in nature, such as negative index of refraction 5,6 or strongly anisotropic materials 7,8 . This has provided tremendous opportunities for novel lens designs with unprecedented resolution 9 . Initiated by Pendry's seminal concept of the perfect lens 10 , a number of superlenses were demonstrated with resolving powers beyond the diffraction limit [11][12][13][14][15][16][17] . The optical superlens first achieved sub-diffraction-limited resolution by enhancing evanescent waves through a slab of silver 11 . As the evanescent-field enhancement is enabled by surface plasmon excitation, the subwavelength image is typically limited to the near field of the metal slab. However, the hyperlens-a metamaterial-based lens-can send super-resolution images into the far field by introducing a magnification mechanism. This has been considered as one of the most promising candidates for practical applications since its first demonstration in 2007 (refs 13,14). Recently, various other metamaterial-based lenses, that is, metalenses, have also been developed with both

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Section: Extraordinary Imaging Properties Of the Hyperbolic Metalensmentioning

confidence: 99%

Section: Extraordinary Imaging Properties Of the Hyperbolic Metalensmentioning

confidence: 99%

Hyperlenses and metalenses for far-field super-resolution imaging

2012

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“…Recent advancements in man-made materials ("metamaterials") have resulted in intriguing achievements in acoustic and phononic transport manipulation [1]. These discoveries include dynamic negative density and a bulk modulus [2][3][4][5][6][7][8], subwavelength imaging [9][10][11], acoustic and surface wave cloaking [12][13][14][15], a phononic band gap [16,17], extraordinary acoustic transmission [18,19], Anderson localization [20], and asymmetric transmission [21][22][23][24][25]. These works, so far, are based on the modulation of the real part of the acoustic parameters.…”

Section: Introductionmentioning

confidence: 99%

PT-Symmetric Acoustics

et al. 2014

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We introduce here the concept of acoustic parity-time (PT ) symmetry and demonstrate the extraordinary scattering characteristics of the acoustic PT medium. On the basis of exact calculations, we show how an acoustic PT -symmetric medium can become unidirectionally transparent at given frequencies. Combining such a PT -symmetric medium with transformation acoustics, we design two-dimensional symmetric acoustic cloaks that are unidirectionally invisible in a prescribed direction. Our results open new possibilities for designing functional acoustic devices with directional responses.

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“…A peculiar kind of metamaterial can be produced by stacking non-interacting waveguides together [47]. A rigid pipe filled with fluid or gas supports acoustic waveguide modes with wavelengths much greater than the diameter of the pipe.…”

Section: Solid Immersion Lenses With Metamaterialsmentioning

confidence: 99%

“…A rigid pipe filled with fluid or gas supports acoustic waveguide modes with wavelengths much greater than the diameter of the pipe. If we stack many such pipes and make every pipe carry one pixel of an image [47], we get what appears to be deeply subwavelength imaging. And if we use expanding pipes to make a 'magnifying hyperlens' [48], then deeply-subwavelength focusing also appears possible.…”

Section: Solid Immersion Lenses With Metamaterialsmentioning

confidence: 99%

Upholding the diffraction limit in the focusing of light and sound

Maznev

Wright

2017

Wave Motion

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The concept of the diffraction limit put forth by Ernst Abbe and others has been an important guiding principle limiting our ability to tightly focus classical waves, such as light and sound, in the far field. In the past decade, numerous reports have described focusing or imaging with light and sound 'below the diffraction limit'. We argue that the diffraction limit defined in a reasonable way, for example in terms of the upper bound on the wave numbers corresponding to the spatial Fourier components of the intensity profile, or in terms of the spot size into which at least 50% of the incident power can be focused, still stands unbroken to this day. We review experimental observations of 'subwavelength' or 'sub-diffraction-limit' focusing, which can be principally broken down into three broad categories: (i) 'super-resolution', i.e. the technique based on the modification of the pupil of the optical system to reduce the width of the central maximum in the intensity distribution at the expense of increasing side bands; (ii) solid immersion lenses, making use of metamaterials with a high effective index; (iii) concentration of intensity by a subwavelength structure such as an antenna. Even though a lot of interesting work has been done along these lines, none of the hitherto performed experiments violated the sensibly defined diffraction limit.

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A holey-structured metamaterial for acoustic deep-subwavelength imaging

Cited by 578 publications

References 36 publications

Hyperlenses and metalenses for far-field super-resolution imaging

Hyperlenses and metalenses for far-field super-resolution imaging

PT-Symmetric Acoustics

Upholding the diffraction limit in the focusing of light and sound

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