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: 6Citation - Scopus: 6Field Correlations for Off-Axis Gaussian Laser Beams in Atmospheric Turbulence(Amer Geophysical Union, 2014) Baykal, YahyaThe absolute field correlations in atmospheric turbulence are evaluated for the off-axis optical Gaussian beam incidence. Evaluations in the practical range of the source and the turbulent medium parameters show that an increase in the diagonal length at the receiver plane causes the absolute field correlations of the off-axis Gaussian beam to decrease. At a fixed receiver diagonal length, the off-axis Gaussian beams having smaller displacement parameters and larger source sizes exhibit larger absolute field correlations. Comparing the absolute field correlations of the off-axis Gaussian beams in atmospheric turbulence with their no turbulence counterparts, it is observed that the behavior of the absolute field correlation variations remains the same; however, the diminishing of the absolute field correlations in turbulence occurs at smaller diagonal lengths.Article Citation - WoS: 16Citation - Scopus: 17Sinusoidal Gaussian Beam Field Correlations(Iop Publishing Ltd, 2012) Baykal, YahyaField correlations of sinusoidal Gaussian beams are formulated in turbulence, and specifically cos Gaussian (cG) and cosh Gaussian (chG) beam field correlations are evaluated versus the diagonal length at the receiver plane. The effects of the displacement parameters, the coordinates of the first receiver point and the source sizes on the field correlations of monochromatic light sources having cG and chG field distributions are investigated when such beams traverse turbulent media. Such parameters affect spatial heterodyne measurement. Field correlations found at the receiver plane reflect the combined variations of diffraction patterns and turbulence effects. To differentiate the diffraction patterns and the turbulence effects, field correlations of cG and chG beams in turbulence and in the absence of turbulence are compared. For cG beams, the oscillatory behaviour of the field correlations versus the diagonal length at the receiver plane in the absence of turbulence becomes smoother in the presence of turbulence. The received fields of cG and chG beams become decorrelated at shorter diagonal distances in turbulence.Article Citation - WoS: 18Citation - Scopus: 19Field Correlations of Flat-Topped Gaussian and Annular Beams in Turbulence(Elsevier Sci Ltd, 2011) Baykal, YahyaStarting from the second order moment formulation for multi-beam incidence, field correlations at the receiver plane of flat-topped Gaussian and annular beams are found in turbulence. Reflecting the information on both the randomness due to turbulence and the field profile of the incident field, field correlations of the fiat-topped Gaussian beams are found to become larger at larger source size, smaller flatness parameters and smaller turbulence strengths. For the annular beam structures, field correlations are larger for thicker beams. Field correlations of larger primary beam sized annular incidences are smaller at smaller diagonal distances and larger at larger diagonal distances. As expected, annular beam field correlations are found to be larger at smaller structure constants and at smaller wavelengths. However, at large link lengths, field correlations could be larger than at smaller link lengths due to fact that for annular beams, the field at the centre of the receiver attains very small value at smaller link lengths, however, on propagation in turbulence, receiver field distribution changes to a Gaussian profile. (C) 2011 Elsevier Ltd. All rights reserved.