Ray Optics at a Deep-Subwavelength Scale: A Transformation Optics Approach

Han, Seung-Hoon; Xiong, Yi; Genov, Dentcho A.; Liu, Zhaowei; Bartal, Guy; Zhang, Xiang

doi:10.1021/nl801942x

Cited by 79 publications

(66 citation statements)

References 38 publications

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“…Practical configurations of the hyperlens were proposed by different groups, including a cylindrical geometry 15,25,26 , tapered metallic wire arrays [27][28][29][30] or uniquely designed material dispersions [31][32][33][34] . To circumvent the problem of absorption in real materials and thereby avoid image distortions in the far field, proper configurational design must ensure that all rays originating from the object plane travel equal path lengths through the metamaterial.…”

Section: Physics Of the Hyperlensmentioning

confidence: 99%

“…Owing to its use of curved surfaces, the cylindrical hyperlens design may not be convenient for bio-imaging. Design of the planar hyperlens has been shown to be theoretically feasible via specific material dispersion based on transformation optics 31,32,37 . In such designs, the metamaterial properties are designed to bend light rays from subwavelength features in such a way as to form a resolvable image on a flat output plane.…”

Section: Physics Of the Hyperlensmentioning

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: Physics Of the Hyperlensmentioning

confidence: 99%

Section: Physics Of the Hyperlensmentioning

confidence: 99%

Hyperlenses and metalenses for far-field super-resolution imaging

2012

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“…Consequently, the sub-diffraction details of the objects are magnified to be above the diffraction limit and can be transmitted to the far field. Since the first experimental demonstration of the cylindrical hyperlens in one dimension 9 , newly improved designs as well as fabrication techniques, such as the impedance-matched 11 , flat 12 , oblate 13,14 , aperiodic 15 and acoustic 16 hyperlenses, have been proposed in the framework of transformational optics [17][18][19] . Nevertheless, all the experimental demonstrations of hyperlenses so far were limited to one-dimensional magnification and ultraviolet (UV) wavelengths, whereas for any practical imaging applications it is critical to demonstrate two-dimensional imaging, with resolution below the diffraction limit in the visible spectrum.…”

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confidence: 99%

Spherical hyperlens for two-dimensional sub-diffractional imaging at visible frequencies

et al. 2010

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Hyperlenses have generated much interest recently, not only because of their intriguing physics but also for their ability to achieve sub-diffraction imaging in the far field in real time. All previous efforts have been limited to sub-wavelength confinement in one dimension only and at ultraviolet frequencies, hindering the use of hyperlenses in practical applications. Here, we report the first experimental demonstration of far-field imaging at a visible wavelength, with resolution beyond the diffraction limit in two lateral dimensions. The spherical hyperlens is designed with flat hyperbolic dispersion that supports wave propagation with very large spatial frequency and yet same phase speed. This allows us to resolve features down to 160 nm, much smaller than the diffraction limit at visible wavelengths, that is, 410 nm. The hyperlens can be integrated into conventional microscopes, expanding their capabilities beyond the diffraction limit and opening a new realm in real-time nanoscopic optical imaging.

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“…The object and image surfaces of a hyperlens are both cylindrical surfaces, which are not convenient for practical applications. Although TO has been utilized to reshape the object or image surface of a hyper-lens (see, e.g., [22,23]), these methods require complicated mathematical calculations/derivations/formulas (and new calculations should be made if the size of the hyper-lens changes).…”

Section: Methods and An Examplementioning

confidence: 99%

Surface Transformation With Homogenous Optic-Null Medium

Sun¹,

He²

2015

PIER

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Abstract-An optical surface transformation (OST) method is proposed briefly in this short paper. Compared with Transformation Optics (TO), we do not need to consider what kinds of coordinate transformation should be used when designing a novel device, but only need to choose the shapes of two end surfaces (namely, the input and output surfaces of the device), which are linked by an optic-null medium (ONM) that is a highly anisotropic homogeneous medium. All devices designed by OST can be realized by some ONM. The design process of an optical device with some pre-designed function can be converted to the simple choice of the shape and size of the optical surfaces with the OST, which will become a simple and yet innovative way to design electromagnetic/optical devices.

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Ray Optics at a Deep-Subwavelength Scale: A Transformation Optics Approach

Cited by 79 publications

References 38 publications

Hyperlenses and metalenses for far-field super-resolution imaging

Hyperlenses and metalenses for far-field super-resolution imaging

Spherical hyperlens for two-dimensional sub-diffractional imaging at visible frequencies

Surface Transformation With Homogenous Optic-Null Medium

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