Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/260
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Article Citation - WoS: 38Citation - Scopus: 42Propagation Factor of Partially Coherent Flat-Topped Beam Array in Free Space and Turbulent Atmosphere(Elsevier Sci Ltd, 2012) Yuan, Yangsheng; Cai, Yangjian; Eyyuboglu, Halil T.; Baykal, Yahya; Chen, JunAnalytical expressions for the propagation factor of partially coherent radial flat-topped (FT) beam array in free-space and turbulent atmosphere are derived. Our formulae can be applied to study the beam propagation factors of partially coherent Gaussian beam, partially coherent FT beam and partially coherent radial Gaussian beam array. The evolution properties of the propagation factors of those beams in turbulent atmosphere are studied numerically and comparatively. From the aspect of the propagation factor, our results show that partially coherent radial FT beam array is less affected by turbulence than partially coherent Gaussian beam, partially coherent FT beam and partially coherent radial Gaussian beam array. (C) 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 9Scintillation Properties of a Truncated Flat-Topped Beam in a Weakly Turbulent Atmosphere(Elsevier Sci Ltd, 2013) Liu, Xianlong; Liang, Chunhao; Yuan, Yangsheng; Cai, Yangjian; Eyyuboglu, Halil T.We derive derive an explicit expression for the scintillation index of a truncated flat-topped (FT) beam in a weakly turbulent atmosphere. Under suitable conditions, the derived formula reduces to the expression for the scintillation index of a FT beam or Gaussian beam without truncation. The scintillation properties of a truncated FT beam in a weakly turbulent atmosphere are illustrated numerically. It is found that the truncation parameter has strong influence on the scintillation properties, and the advantage of a FT beam over a Gaussian beam for reducing the negative influence of turbulence disappears gradually as the truncation parameter decreases. (C) 2012 Elsevier Ltd. All rights reserved.Article Citation - WoS: 26Citation - Scopus: 33Propagation Factors of Hermite-Gaussian Beams in Turbulent Atmosphere(Elsevier Sci Ltd, 2010) Yuan, Yangsheng; Cai, Yangjian; Qu, Jun; Eyyuboglu, Halil T.; Baykal, YahyaBased on the extended Huygens-Fresnel integral and the second-order moments of the Wigner distribution function, an analytical formulae for the propagation factors (M-2-factors) of coherent and partially coherent one-dimensional Hermite-Gaussian beams in a turbulent atmosphere are derived. Evolution properties of the M-2-factor of the Hermite-Gaussian beam in a turbulent atmosphere are studied numerically in detail. Our results show that the M-2-factor of the Hermite-Gaussian beam increases upon propagation in a turbulent atmosphere. The M-2-factor of the Hermite-Gaussian beam with larger beam order (or lower coherence) increases slower that of the Hermite-Gaussian beam with smaller beam order (or higher coherence) in a turbulent atmosphere, which means that the Hermite-Gaussian beam with a larger beam order and lower coherence is less affected by a turbulent atmosphere. Our results will be useful in long-distance free-space optical communications. (c) 2010 Elsevier Ltd. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 10Propagation of Various Dark Hollow Beams Through an Optical System in Turbulent Atmosphere(Elsevier Sci Ltd, 2010) Cai, Yangjian; Eyyuboglu, Halil T.; Baykal, Yahya; Eyyubolu, Halil T.The propagation of a dark hollow beam (DHB) of circular, elliptical or rectangular symmetry through aligned and misaligned ABCD optical systems in turbulent atmosphere is investigated. Analytical propagation formulae for the average intensities of various DHBs are derived based on the extended Huygens-Fresnel integral. As a numerical example, the focusing properties of various DHBs in turbulent atmosphere are studied It is found that the focusing properties of various DHBs in turbulent atmosphere are much different from their focusing properties in free space (C) 2010 Elsevier Ltd. All rights reserved.