1,720,974 research outputs found
Optical superresolution without evanescent waves
No full textWe show that arbitrarily small localization of light of prescribed profile can be created within a finite area of space using a mask illuminated by a monochromatic plane wave, without evanescent waves
Near-Field Plasmonics of an Individual Dielectric Nanoparticle above a Metallic Substrate
No full textWe simulate and discuss the local electric-field enhancement in a system of a dielectric nanoparticle placed very near to a metallic substrate. We use finite-element numerical simulations in order to understand the field-enhancement mechanism in this dielectric NP-on-mirror system. Under appropriate excitation conditions, the gap between the particle and the substrate becomes a "hot spot", i.e., a region of intense electromagnetic field. We also show how the optical properties of the dielectric NP placed on a metallic substrate affect the plasmonic field enhancement in the nanogap and characterize the confinement in the gap. Our study helps to understand and design systems with dielectric NPs on metallic substrates which can be equally as effective for SERS, fluorescence, and nonlinear phenomena as conventional all plasmonic structures.</p
Super-resolution without evanescent waves
No full textThe past decade has seen numerous efforts to achieve imaging resolution beyond that of the Abbe-Rayleigh diffraction limit. The main direction of research aiming to break this limit seeks to exploit the evanescent components containing fine detail of the electromagnetic field distribution at the immediate proximity of the object. Here, we propose a solution that removes the need for evanescent fields. The object being imaged or stimulated with subwavelength accuracy does not need to be in the immediate proximity of the superlens or field concentrator: an optical mask can be designed that creates constructive interference of waves known as superoscillation, leading to a subwavelength focus of prescribed size and shape in a field of view beyond the evanescent fields, when illuminated by a monochromatic wave. Moreover, we demonstrate that such a mask may be used not only as a focusing device but also as a super-resolution imaging device
Focal-plane arrays: nanohole arrays enable multiple-point-source imaging
No full textA new type of focal-plane array made of a nanoscale metal screen mimics the function of a lens, focuses light (and plasmons) into subwavelength hot spots, and achieves high-resolution imaging of complex sources
Subwavelength localization of light on double-periodic nanowire metamaterials
No full textWe relate localization of light to resonant transmission of planar metamaterial nano-wire array and show that due to plasmon resonance optical near-field distributions show a strong dependence on the wavelength and polarization
Optical super-resolution through super-oscillations
Full text linkWe demonstrate that a quasi-periodic array of nanoholes in a metal screen can focus light into subwavelength spots in the far-field without contributions from evanescent fields. The subwavelength spots were observed with a conventional optical microscope and mapped to the far-field. We relate the formation of subwavelength light localizations in the far-field to the phenomenon of super-oscillations. This effect offers a new way to achieve subwavelength imaging, which differs from approaches based on the recovery of evanescent fields
Subwavelength focusing of light without evanescent waves by an array of nanoholes
No full textWe provide the first evidence of free-space subwavelength focusing without evanescent fields using a photonic nano-structure. Hot-spots smaller than half of the wavelength were observed at distances of tens of wavelengths from the structure
Lensless focusing with subwavelength resolution by an array of nanoholes
Full text linkWe provide the first experimental evidence of focusing light into subwavelength spots by a 2-dimensional planar photonic structure. When a quasi-periodic array of nanoholes was illuminated with coherent light sources, it created very rich diffraction patterns at different heights to the array. At specific heights, we observed diffraction patterns containing subwavelength spots. The ability to focus light into subwavelength spots is of fundamental importance for applications in a wide range of areas, e.g. microscopy, photo lithography, data storage etc
Far-field subwavelength focusing of light and plasmons by the Talbot effect
Full text linkWe demonstrate experimentally and theoretically that the Talbot effect on arrays of nano-holes may be used to achieve subwavelength localizations of optical and plasmonic fields
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