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Elektronik ve Haberleşme Mühendisliği Bölümü

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Browsing Elektronik ve Haberleşme Mühendisliği Bölümü by Subject "Coherence"

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    Citation - WoS: 34
    Citation - Scopus: 35
    Average Transmittance in Turbulence for Partially Coherent Sources
    (Elsevier, 2004) Baykal, Y
    Average intensity and power-transmittance in turbulence are formulated for a source with arbitrary degree of coherence (both spatial and temporal). Average power-transmittance is shown to reduce to the average intensity-transmittance if the receiver dimension is much less than the beam size. The average transmittance is found to attain its minimum value when the source is on the order of the Fresnel zone, irrespective of the degree of coherence of the source. We obtain the correct average intensity when the source is coherent, partially coherent and incoherent. Average transmittances due to turbulence are found for practical FSO (Free Space Optics) communication links. (C) 2003 Elsevier B.V. All rights reserved.
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    Article
    Citation - WoS: 41
    Citation - Scopus: 46
    Transmittance of Partially Coherent Cosh-Gaussian, Cos-Gaussian and Annular Beams in Turbulence
    (Elsevier Science Bv, 2007) Eyyuboglu, Halil T.; Baykal, Yahya
    Average relative power transmittance is evaluated, by incorporating atmospheric turbulence, for partially coherent cosh-Gaussian, cos-Gaussian, Gaussian and annular beams. For all the collimated versions of these beams, against the increasing propagation length, there is a typical trend of the decrease in the relative average power transmittance with incremental drop being much less for partially coherent cos-Gaussian beams. The change in the transmittance versus the propagation length will be similar to the corresponding collimated cases, when these beams are focused at a certain focal length. Also partially coherent beams are less sensitive to propagation length changes, except for cos-Gaussian case. Partially coherent cosh-Gaussian beams exhibit a drop in the transmittance as the displacement parameter of the beam is made larger, whereas this trend is just the opposite for partially coherent cos-Gaussian beams. When examined versus the source size, for all the four types of beams, the transmittance has a similar behavior, i.e., it becomes high at small source sizes, falling with increasing source size, and following a dip, it starts to rise, eventually approaching the plane wave limit of unity. The occurrence of the dip coincides with the smallest source size for cosh-Gaussian, with the largest for cos-Gaussian, and about the same source size for Gaussian and annular beams. In general, the average relative power transmittance of coherent beam is affected much more than the partially coherent beams against the variations in source properties. (c) 2007 Elsevier B.V. All rights reserved.