Super-resolution imaging through a planar silver layer

Optics Express (Impact Factor: 3.49). 04/2005; 13(6):2127-34. DOI: 10.1364/OPEX.13.002127
Source: PubMed


It has been proposed that a planar silver layer could be used to project a super-resolution image in the near field when illuminated near its plasma frequency [J. B. Pendry, Phys. Rev. Lett. 86, 3966 (2000)]. This has been investigated experimentally using a modified form of conformal-mask photolithography, where dielectric spacers and silver layers are coated onto a tungsten-on-glass mask. We report here on the experimental confirmation that super-resolution imaging can be achieved using a 50-nm thick planar silver layer as a near-field lens at wavelengths around 365 nm. Gratings with periods down to 145 nm have been resolved, which agrees well with our finite-difference time domain (FDTD) simulations.

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    • "Consideration of just the first term in Eq. (4) would lead to the conclusion that a flat lens simply requires < 0. However, the higher order term in Eq. (4) has a sign opposite to that of the first term, indicating that increases in the thickness of a negative permittivity layer generally counteract phase conditions necessary to make a flat lens. Given the connection we have shown between a real paraxial image and a super-resolution image, this could explain why an early attempt to make a flat lens using a thicker silver layer did not achieve super-resolution [9] [10], whereas later attempts using thinner silver layers did [12] [13] [14]. "
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    ABSTRACT: We show that a classical imaging criterion based on angular dependence of small-angle phase can be applied to any system composed of planar, uniform media to determine if it is a flat lens capable of forming a real paraxial image and to estimate the image location. The real paraxial image location obtained by this method shows agreement with past demonstrations of far-field flat-lens imaging and can even predict the location of super-resolved images in the near-field. The generality of this criterion leads to several new predictions: flat lenses for transverse-electric polarization using dielectric layers, a broadband flat lens working across the ultraviolet-visible spectrum, and a flat lens configuration with an image plane located up to several wavelengths from the exit surface. These predictions are supported by full-wave simulations. Our work shows that small-angle phase can be used as a generic metric to categorize and design flat lenses.
    Optics Express 12/2014; 22(24). DOI:10.1364/OE.22.029340 · 3.49 Impact Factor
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    • "At present, the near-field superresolution optical imaging with silver layer superlens, photonic crystal, metal or medium metamaterial has been realized in the world. Among which, the use of SPPs (surface plasmon polaritons ) with metal nano structure to enhance the evanescent wave of the nanoscale structure information to realize optical superresolution imaging receives more attention from the researchers [8] [9] [10]. "
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    ABSTRACT: The optical transfer function of the far-field superlens imaging system is established in this thesis to make it easy to describe the corresponding relation between the far-field angular spectrum and the near-field object superresolution information. We utilized the established optical transfer function to make detailed research on the imaging characteristics of the far-field superresolution, also reconstruct the near-field nano-information through the far-field angular spectrum, which proves that the resolution of the far-field superlens with structure coupled with metal grating can reach 50 nm, and provides a helpful reference for the study of the new optical microscope imaging of superresolution. Crown Copyright
    Optik - International Journal for Light and Electron Optics 01/2014; 125(1):208-211. DOI:10.1016/j.ijleo.2013.06.018 · 0.68 Impact Factor
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    • "The electric permittivities of the layers are selected so that an effective refractive index of the composite material be equal to n = −1. Experiments on the superresolution through superlenses were reported in [2] [3]. In the experiments, a superresolution of 0.4λ was achieved [2]. "
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    ABSTRACT: By solving Helmholtz equations, relationships to describe propagating modes in an arbitrary graded-index planar waveguide are derived. We show that in the quadratic- and secant-index waveguides a minimal mode width is 0.4 λ / n , where λ is the wavelength in free space and n is the refractive index on the fiber axis. By modeling in FullWAVE, we show that the high-resolution imaging can be achieved with half-pitch graded-index Mikaelian microlenses (ML) and Maxwell’s “fisheye” lenses. It is shown that using a 2D ML, the point source can be imaged near the lens surface as a light spot with the full width at half maximum (FWHM) of 0.12λ. This value is close to the diffraction limit for silicon ( n = 3.47 ) in 2D media FWHM = 0.44 λ / n = 0.127 λ. We also show that half-pitch ML is able to resolve at half-maximum two close point sources separated by a 0.3λ distance.
    Advances in Optical Technologies 01/2012; 2012(21). DOI:10.1155/2012/647165
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