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Proceedings Paper

Optimisation of a plasmonic nanolens: increase of transmission and focal length
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Paper Abstract

In a numerical experiment, we optimise performance of plasmonic lenses with different structures of single metal nanolayers. The nanolenses, either with double sided grooved or with slits act like classical, high-numerical aperture, refractive objectives. Their focal regions are well defined and different from those of diffractive optical elements. The narrowest rotationally symmetric foci are achieved for a Laguerre-Gauss intensity profile with radial polarization. The highest transmission reaching 80% is achieved for high slit width-to-lattice constant ratios when light is waveguided in annular slits. In grooved and continuous metal lenses transmission reaches 30% due to resonant tunnelling of plasmons. Location of slit/groove edges, which act as sources of spherical waves, and light intensity at them decides on interference of radial and longitudinal electric field components in focal region. Proper choice of lattice constants and surface structure allows for focal length several times larger than the free space light wavelength. All simulations are made using body-of-revolution finite difference time domain method and Drude model parameters of silver. In simulations we accept parameters of the nanolenses which are possible to fabricate with technical equipment available to us.

Paper Details

Date Published: 29 April 2010
PDF: 7 pages
Proc. SPIE 7711, Metamaterials V, 77110I (29 April 2010); doi: 10.1117/12.855511
Show Author Affiliations
Piotr Wróbel, Univ. of Warsaw (Poland)
Tomasz J. Antosiewicz, Univ. of Warsaw (Poland)
Tomasz Szoplik, Univ. of Warsaw (Poland)

Published in SPIE Proceedings Vol. 7711:
Metamaterials V
Nigel P. Johnson; Ekmel Özbay; Richard W. Ziolkowski; Nikolay I. Zheludev, Editor(s)

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