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Superfocusing of optical beams below the diffraction limit by media with negative refraction
Author(s) -
Husakou A.,
Herrmann J.
Publication year - 2007
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200776402
Subject(s) - optics , diffraction , wavelength , light beam , slab , aperture (computer memory) , lithography , beam (structure) , physics , superlens , photonic crystal , negative refraction , refraction , near field optics , light field , focus (optics) , limit (mathematics) , optoelectronics , evanescent wave , metamaterial , optical microscope , mathematical analysis , mathematics , scanning electron microscope , geophysics , acoustics
Usual optical elements cannot focus a light beam to a spot with diameter smaller than half of the wavelength of the light; however overcoming this limit is of great importance in several high‐tech applications such as optical lithography, magneto‐optical data storage, and numerous other fields of science and industry. Here we show that it is possible to focus light to spots below the diffraction limit (superfocusing) by the combination of two main elements: one which creates weak near‐field evanescent components of the beam, and one which amplifies these evanescent fields, such as a slab of a photonic crystal with negative refraction. For the creation of seed evanescent components a wavelength‐scale aperture can be used. For superfocusing of scanning beams a light‐controlled saturable absorber or a nonlinear material with a Kerr‐type nonlinearity enables focusing of beams without spatial near‐field control to spots in the range of 0.2 λ . (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)