Elektrik Elektronik Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/411
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Article Citation - WoS: 3Citation - Scopus: 3Performance Evaluation of Aeronautical Uplink/Downlink Free-Space Optical Communication System With Adaptive Optics Over Gamma-Gamma Turbulence Channel(Iop Publishing Ltd, 2022) Baykal, Yahya; Gokce, Muhsin Caner; Ata, YalcinIn this study, we analyze the effect of adaptive optics corrections on the performance of an aeronautical free-space optical (FSO) system with bidirectional slant path uplink and downlink communication channels. The aeronautical FSO communication (FSOC) system operates in a gamma-gamma atmospheric turbulence channel and employs adaptive optics corrections for the distorted wave front of the Gaussian beam wave. The modulation type of the aeronautical FSOC system is chosen to be M-ary phase-shift-keying-subcarrier intensity modulation and the type of the employed photodetector is positive-intrinsic-negative. In analysis, the effect of system parameters such as zenith angle, the height of transmitter/receiver on the ground, M-ary level, filter bandwidth, link distance, and the adaptive optics correction modes on bit-error-rate are demonstrated.Article Citation - WoS: 5Effect of Anisotropy on Performance of M-Ary Phase Shift Keying Subcarrier Intensity-Modulated Optical Wireless Communication Links Operating in Strong Oceanic Turbulence(Iop Publishing Ltd, 2020) Baykal, Yahya; Ata, Yalcin; Gokce, Muhsin CanerIn strong oceanic turbulence, the performance of M-ary phase shift keying subcarrier intensity-modulated optical wireless communication (OWC) links is investigated in terms of the bit-error-rate (BER) by considering the effect of anisotropy of the oceanic channel. To calculate the BER of the OWC link, a gamma-gamma statistical channel model is adopted. The extended Huygens-Fresnel principle and the asymptotic Rytov theory are used to obtain the received optical power and the large-scale and small-scale log-intensity variances, respectively. Our graphical illustrations include the BER versus anisotropic factor for various system parameters such as the modulation order, filter bandwidth, link distance, peak amplitude of each subcarrier and the oceanic turbulence parameters.Article Citation - WoS: 26Citation - Scopus: 35Propagation of a Radially Polarized Twisted Gaussian Schell-Model Beam in Turbulent Atmosphere(Iop Publishing Ltd, 2016) Peng, Xiaofeng; Liu, Lin; Yu, Jiayi; Liu, Xianlong; Cai, Yangjian; Baykal, Yahya; Li, WeiPropagation properties of a scalar twisted Gaussian Schell-model (TGSM) beam in turbulent atmosphere has been studied in detail. In this paper, we explore the propagation properties of a radially polarized TGSM beam in turbulent atmosphere. Analytical formulae for the elements of the cross-spectral density matrix of a radially polarized TGSM beam propagating in turbulent atmosphere are derived based on the extended Huygens-Fresnel integral. We find that the atmospheric turbulence induces degeneration of the intensity distribution and depolarization of a radially polarized TGSM beam on propagation, while the twist phase plays a role in antidegradation and anti-depolarization. Furthermore, we also find that the twist phase induces not only the rotation of the beam spot but also changes of the state of polarization on propagation, which are caused by the fact that the twist phase imposes orbital angular momentum on the beam. Thus, the twist phase can be used to control the propagation properties of radially polarized partially coherent beam. Our results will be useful in some applications, such as optical trapping and free-space optical communications.