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Journal of Atomic, Molecular, and Optical Physics
Volume 2012 (2012), Article ID 123872, 3 pages
http://dx.doi.org/10.1155/2012/123872
Research Article

Elongated Photonic Nanojet from Truncated Cylindrical Zone Plate

Laser Measurements Laboratory, Image Processing Systems Institute, Russian Academy of Sciences, 151 Molodogvardeyskaya Street, Samara 443001, Russia

Received 31 July 2012; Accepted 18 October 2012

Academic Editor: Keli Han

Copyright © 2012 Sergey S. Stafeev and Victor V. Kotlyar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Previously (Chen et al., 2004), it was shown that dielectric cylinder can form focal spots with small diameters and long depth. This type of focal spot was called photonic nanojet. In this paper, it was shown that dielectric cylinder of radius 595 nm (1.12 of wavelength) forms near the surface a photonic nanojet with diameter equal to 0.31 of wavelength and depth of focus equal to 0.57 of wavelength. Adding truncated concentric rings with radiuses equal to radiuses of zone plate to the cylinder increases the depth of focus to 1.18 of the wavelength. The diameter and intensity of focal spot near the cylinder surface remain unchanged.