Refractive transmission of light and beam shapingwith metallic nano-optic lenses

Sun, Zhijun; Kim, Hong Koo

doi:10.1063/1.1776327

Cited by 249 publications

(147 citation statements)

References 18 publications

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“…The underlying design principle is to satisfy the phase matching condition to constructively bring plane waves from air into deep subwavelength focus inside the metamaterial. This can be accomplished by either geometric variations, such as plasmonic waveguide couplers (PWC) 18,[51][52][53] and shaped metamaterial-air interfaces 19,54 , or material refractive-index variations like gradient-index (GRIN) metamaterials 20 . For example, a PWC, composed of an array of specially designed non-periodic metalinsulator-metal waveguides, can turn non-flat wave-fronts at the metamaterial-PWC interface into flat ones at the PWC-air interface, thus matching the phase condition for realizing a deep subwavelength focus inside the metamaterial slab 18,51 .…”

Section: Principles Of the Metalensmentioning

confidence: 99%

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: Principles Of the Metalensmentioning

confidence: 99%

Hyperlenses and metalenses for far-field super-resolution imaging

2012

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“…The basic degrees of freedom include changing the width of the slits, assuming a cylindrical holey lens, their relative positions and the shape of the entrance and exit surfaces. An early idea inspired in thick left-handed metamaterial lenses is based on creating metallic lenses with curved surfaces, resembling glass lenses in their shape, such that each nanoslit transmits light with a phase retardation which is controlled by the metal thickness [32]. However, efficient fabrication processes may benefit from keeping the film thickness fixed but tailoring alternate geometrical parameters of the holey metallic device.…”

Section: Gradient-index Metalensesmentioning

confidence: 99%

Recent Progress in Far-Field Optical Metalenses

Naserpour¹,

Hashemi²,

Rodríguez³

2017

Metamaterials - Devices and Applications

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In this chapter, a review of the recent advances in optical metalenses is presented, with special emphasis in their experimental implementation. First, the Huygens' principle applied to ultrathin engineered metamaterials is introduced for the purpose of giving curvature to the wavefront of free-space wave fields. Primary designs based on metallic nanoslits and holey screens occasionally with variant width are first examined. Holographic plasmonic lenses are also explored offering a promising route to realize nanophotonic components. More recent metasurfaces based on nano-antenna resonators, either plasmonic or high-index dielectric, are analyzed in detail. Furthermore, 2D material lenses in the scale of a few nanometers enabling the thinnest lenses to date are here considered. Finally, dynamically reconfigurable focusing devices are reported for creating a scenario with new functionalities.

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“…However, diffraction may put the usefulness of the microlens in question in sub-2 m pixels [28]. Recent progress in nanotechnology and the theory of plasmonics has led to rapidly growing interest in the implementation of metallic optical elements on a nano-scale for light beam manipulation [29][30][31][32][33][34][35][36][37][38][39]. Especially, lots of theoretical predictions [30][31][32][33][34][35] and experimental demonstration [28,[36][37][38][39] have been reported on both one-dimensional (1D) and 2D PLs.…”

Section: Introductionmentioning

confidence: 99%