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: 183Citation - Scopus: 193Analysis of Reciprocity of Cos-Gaussian and Cosh-Gaussian Laser Beams in a Turbulent Atmosphere(Optical Soc Amer, 2004) Eyyuboglu, HT; Baykal, YIn a turbulent atmosphere, starting with a cos-Gaussian excitation at the source plane, the average intensity profile at the receiver plane is formulated. This average intensity profile is evaluated against the variations of link lengths, turbulence levels, two frequently used free-space optics wavelengths, and beam displacement parameters. We show that a cos-Gaussian beam, following a natural diffraction, is eventually transformed into a cosh-Gaussian beam. Combining our earlier results with the current findings, we conclude that cos-Gaussian and cosh-Gaussian beams act in a reciprocal manner after propagation in turbulence. The rates (paces) of conversion in the two directions are not the same. Although the conversion of cos-Gaussian beams to cosh-Gaussian beams can happen over a wide range of turbulence levels (low to moderate to high), the conversion of cosh-Gaussian beams to cos-Gaussian beams is pronounced under relatively stronger turbulence conditions. Source and propagation parameters that affect this reciprocity have been analyzed. (C) 2004 Optical Society of America.Article Citation - WoS: 127Citation - Scopus: 135Average Intensity and Spreading of Cosh-Gaussian Laser Beams in the Turbulent Atmosphere(Optical Soc Amer, 2005) Eyyuboglu, HT; Baykal, YThe average intensity and spreading of cosh-Gaussian laser beams in the turbulent atmosphere are examined. Our research is based principally on formulating the average-intensity profile at the receiver plane for cosh-Gaussian excitation. The limiting cases of our formulation for the average intensity are found to reduce correctly to the existing Gaussian beam wave result in turbulence and the cosh-Gaussian beam result in free space (in the absence of turbulence). The average intensity and the broadening of the cosh-Gaussian beam wave after it propagates in the turbulent atmosphere are numerically evaluated versus source size, beam displacement, link length, structure constant, and two wavelengths of 0.85 and 1.55 mum, which are most widely used in currently employed free-space-optical links. Results indicate that in turbulence the beam is widened beyond its free-space diffraction values. At the receiver plane, analogous to the case of free space, this diffraction eventually leads to transformation of the cosh-Gaussian beam into an oscillatory average-intensity profile with a Gaussian envelope. (C) 2005 Optical Society of America.Article Citation - WoS: 83Citation - Scopus: 86Hermite-Cosine Laser Beam and Its Propagation Characteristics in Turbulent Atmosphere(Optical Soc Amer, 2005) Eyyuboglu, HTHermite-cosine-Gaussian (HcosG) laser beams are studied. The source plane intensity of the HcosG beam is introduced and its dependence on the source parameters is examined. By application of the Fresnel diffraction integral, the average receiver intensity of HcosG beam is formulated for the case of propagation in turbulent atmosphere. The average receiver intensity is seen to reduce appropriately to various special cases. When traveling in turbulence, the HcosG beam initially experiences the merging of neighboring beam lobes, and then a TEM-type cosh-Gaussian beam is formed, temporarily leading to a plain cosh-Gaussian beam. Eventually a pure Gaussian beam results. The numerical evaluation of the normalized beam size along the propagation axis at selected mode indices indicates that relative spreading of higher-order HcosG beam modes is less than that of the lower-order counterparts. Consequently, it is possible at some propagation distances to capture more power by using higher-mode-indexed HcosG beams. (C) 2005 Optical Society of America.Article Citation - WoS: 62Citation - Scopus: 72Hermite-Sine and Hermite-Sinh Laser Beams in Turbulent Atmosphere(Optical Soc Amer, 2005) Eyyuboglu, HT; Baykal, YHermite-sine-Gaussian and Hermite-sinh-Gaussian laser beam intensities in a turbulent atmosphere are investigated. The received intensity is formulated by applying the extended Huygens-Fresnel principle to generalized Hermite-hyperbolic-Gaussian and Hermite-sinusoidal-Gaussian beam incidences. From this result, the association to different types of Hermite-hyperbolic-Gaussian and Hermite-sinusoidal-Gaussian beams are defined. The average receiver intensity expressions for Hermite-sine-Gaussian and Hermite-sinh-Gaussian laser beams are evaluated and plotted against the variations in source parameters and propagation conditions. It is observed that the propagation of Hermite-sine-Gaussian and Hermite-sinh-Gaussian laser beams in turbulence have many similarities to their counterparts, Hermite-cosine-Gaussian and Hermite-cosh-Gaussian laser beams, that are examined earlier. It is further observed that under certain conditions the main features of the previously established reciprocity concept between cosine-Gaussian and cosh-Gaussian beams are mostly applicable to Hermite-sine-Gaussian and Hermite-sinh-Gaussian laser beams. (c) 2005 Optical Society of America.