Realization of deep subwavelength resolution with singular media

Xu, Su; Jiang, Yuyu; Xu, Hongyi; Wang, Junxia; Lin, Shisheng; Chen, Hongsheng; Zhang, Baile

doi:10.1038/srep05212

Cited by 19 publications

(18 citation statements)

References 54 publications

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“…As discussed in detail below, this alternative approach has strong potential to enable a low-loss hyperlenses. However, until now, it had only been designed and demonstrated in the microwave frequency range and in acoustics 29 30 31 , while the challenge of fabricating such structures in the optical frequency range has still not been overcome.…”

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confidence: 99%

Experimental demonstration of a non-resonant hyperlens in the visible spectral range

2015

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A metamaterial hyperlens offers a solution to overcome the diffraction limit by transforming evanescent waves responsible for imaging subwavelength features of an object into propagating waves. However, the first realizations of optical hyperlenses were limited by significant resonance-induced losses. Here we report the experimental demonstration of a non-resonant waveguide-coupled hyperlens operating in the visible wavelength range. A detailed investigation of various materials systems proves that a radial fan-shaped configuration is superior to the concentric layer-based configuration in that it relies on non-resonant negative dielectric response, and, as a result, enables low-loss performance in the visible range.

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confidence: 99%

Experimental demonstration of a non-resonant hyperlens in the visible spectral range

2015

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“…Emission modeling is a more complex process. The only emission related quantity found in our model, to the band-edge [25,26]. Thus, the luminescence is on/off when: (i) by Auger recombination of the photoexcited carriers on the trapping states the QD becomes neutral/charged [27] or (ii) charge fluctuations make the trapping sites inactive/active [20,28].…”

Section: Emission Considerationsmentioning

confidence: 92%

Strain influence on optical absorption of giant semiconductor colloidal quantum dots

Pahomi

Cheche

2014

Chemical Physics Letters

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Abstract. The lattice mismatch strain field of core/multishell structures with spherical symmetry is modeled by a linear continuum elasticity approach. The effect of the strain on the energy structure and linear optical absorption in large core/shell/shell spherical semiconductor quantum dots is analyzed. Localization of the photoexcited carriers induced by coating is found to play an important role in explaining the optical stability of large CdSe/CdS/ZnS and ZnTe/ZnSe/ZnS quantum dots. IntroductionAs 'The Next Big Thing' in photovoltaics [1], the colloidal multishell semiconductor quantum dots (QDs) have led to the development of high-efficiency solar cells. To overcome the crystal irregularities induced by the lattice mismatch in the synthesis of these colloidal nanocrystals, the use of a strain-adapting intermediate shell in core/shell (CS) QDs has been proposed. Thus, 'giant' core/shell/shell (CSS) QDs of 18-19 monolayers shell thickness of are synthesized [2,3]. There are several theoretical studies of multi-component nanocrystals, in which the role of the strain is considered by first-principle calculations, by using, for example, the density-functional tight-binding method [4] or local density approximation [5] or densityfunctional theory [6]. Unfortunately, limitations of these ab-initio calculations (e.g., bandgap underestimation) make difficult comparison of their results with the experiment. More important, the main problem of the first-principle calculations, the computational cost, can make the method inadequate for larger structures, such as the large CSS QDs. On the other hand, the widely used for analyzing the linear elasticity of epitaxial strained heterointerfaces, the valence force field method (see, e.g., Ref. [7]) is dependent on a priori information regarding the interface structure and surface passivation. The continuum elasticity approach in the limits of homogeneous and isotropic materials has been shown to be in good agreement with the valence force field models * E-mail: cheche@gate.sinica.edu.twTel.: +40 724 536 908 2 for semiconductor QDs of spherical shape and cubic symmetry (see, e.g., Ref. [8]). In this context, we propose a continuum elasticity model for the lattice mismatch strain field in such nanocrystals. Keeping justified simplicity, based on our strain field model, we consider a twoband model within the effective mass approximation to theoretically investigate the energy structure and light absorption of a CSS QD with thick shells. In our model, we consider ideal multilayer structures. We assume the defects and impurities with low concentration are located at the interfaces, as reported by experiment, (see, e.g., Ref.[9]), and consequently, do not significantly influence the lattice mismatch strain field. Theoretical model Strain field and the band lineup in the presence of strainFirst, we describe our method for calculus of the lattice mismatch strain field. For spherical core/shell nanocrystals the displacement ( u ) has radial symmetry, that is the field is irrotation...

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“…The Ag(111) substrate was cleaned by cycles of Ar + bombardment and annealing, then Si was evaporated onto Ag(111) substrate from a high-purity silicon wafer to form silicene films. The detailed growth method of silicene films is described elsewhere [13,14]. Ag was deposited from a standard Knudsen cell onto the as-grown silicene films at 150 K. All STM/STS and Raman spectroscopy measurements were performed at 77 K. The differential conductance dI/dV spectra were acquired by using a standard lock-in technique with a 20 mV modulation at 937 Hz.…”

Section: Methodsmentioning

confidence: 99%

Metal–silicene interaction studied by scanning tunneling microscopy

Feng

Zhuang

et al. 2015

J. Phys.: Condens. Matter

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Ag atoms have been deposited on 3 × 3 silicene and √3 × √3 silicene films by molecular beam epitaxy method in ultrahigh vacuum. Using scanning tunneling microscopy and Raman spectroscopy, we found that Ag atoms do not form chemical bonds with both 3 × 3 silicene and √3 × √3 silicene films, which is due to the chemically inert surface of silicene. On 3 × 3 silicene films, Ag atoms mostly form into stable flat-top Ag islands. In contrast, Ag atoms form nanoclusters and glide on silicene films, suggesting a more inert nature. Raman spectroscopy suggests that there is more sp (2) hybridization in √3 × √3 than in √7 × √7/3 × 3 silicene films.

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Realization of deep subwavelength resolution with singular media

Cited by 19 publications

References 54 publications

Experimental demonstration of a non-resonant hyperlens in the visible spectral range

Experimental demonstration of a non-resonant hyperlens in the visible spectral range

Strain influence on optical absorption of giant semiconductor colloidal quantum dots

Metal–silicene interaction studied by scanning tunneling microscopy

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