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: 136Citation - Scopus: 148M<sup>2</Sup>-factor of Coherent and Partially Coherent Dark Hollow Beams Propagating in Turbulent Atmosphere(Optical Soc Amer, 2009) Yuan, Yangsheng; Cai, Yangjian; Qu, Jun; Eyyuboglu, Halil T.; Bayka, Yahya; Korotkova, Olga; Baykal, YahyaAnalytical formula is derived for the M-2-factor of coherent and partially coherent dark hollow beams (DHB) in turbulent atmosphere based on the extended Huygens-Fresnel integral and the second-order moments of the Wigner distribution function. Our numerical results show that the M-2-factor of a DHB in turbulent atmosphere increases on propagation, which is much different from its invariant properties in free-space, and is mainly determined by the parameters of the beam and the atmosphere. The relative M-2-factor of a DHB increases slower than that of Gaussian and flat-topped beams on propagation, which means a DHB is less affected by the atmospheric turbulence than Gaussian and flat-topped beams. Furthermore, the relative M-2-factor of a DHB with lower coherence, longer wavelength and larger dark size is less affected by the atmospheric turbulence. Our results will be useful in long-distance free-space optical communications. (C) 2009 Optical Society of AmericaArticle Citation - WoS: 53Citation - Scopus: 58Average Intensity and Spreading of an Elegant Hermite-Gaussian Beam in Turbulent Atmosphere(Optical Soc Amer, 2009) Yuan, Yangsheng; Cai, Yangjian; Qu, Jun; Eyyuboglu, Halil T.; Baykal, YahyaThe propagation of an elegant Hermite-Gaussian beam (EHGB) in turbulent atmosphere is investigated. Analytical propagation formulae for the average intensity and effective beam size of an EHGB in turbulent atmosphere are derived based on the extended Huygens-Fresnel integral. The corresponding results of a standard Hermite-Gaussian beam (SHGB) in turbulent atmosphere are also derived for the convenience of comparison. The intensity and spreading properties of EHGBs and SHGBs in turbulent atmosphere are studied numerically and comparatively. It is found that the propagation properties of EHGBs and SHGBs are much different from their properties in free space, and the EHGB and SHGB with higher orders are less affected by the turbulence. What's more, the SHGB spreads more rapidly than the EHGB in turbulent atmosphere under the same conditions. Our results will be useful in long-distance free-space optical communications. (C) 2009 Optical Society of America