Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651
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Article Citation - WoS: 4Citation - Scopus: 4The Performance Bounds of an Optical Communication System Using Irradiance Profile Modulation(Taylor & Francis Ltd, 2017) Eyyuboglu, Halil T.We assess the performance bounds of an optical communication system that uses irradiance profile modulation. This modulation is based on the four different orders of vortex beams. To this end, we find the turbulence induced average irradiance profiles of Gaussian, Bessel-Gaussian and modified Bessel-Gaussian vortex beams on the receiver plane. Each one is then cross correlated against the free space equivalents. Plotting the cross-correlation coefficients, it becomes possible to identify the borders of correct decision and error regions, thus, deduce the performance bounds of such a system. When measured in terms of structure constant, i.e. the turbulence strength and the propagation length being fixed to 3km, it is seen that the error region extends beyond the structure constant values of 10(-13) m(-2/3) and higher. There seem to be some variations with the beam type and the order of the vortex beam. The performance of Bessel-Gaussian vortex beam comes out to be slightly better than the rest.Article Citation - WoS: 1Citation - Scopus: 1Mode Coupling in Vortex Beams(Elsevier Sci Ltd, 2018) Eyyuboglu, Halil T.We examine the mode coupling in vortex beams. Mode coupling also known as the crosstalk takes place due to turbulent characteristics of the atmospheric communication medium. This way, the transmitted intrinsic mode of the vortex beam leaks power to other extrinsic modes, thus preventing the correct detection of the transmitted symbol which is usually encoded into the mode index or the orbital angular momentum state of the vortex beam. Here we investigate the normalized power mode coupling ratios of several types of vortex beams, namely, Gaussian vortex beam, Bessel Gaussian beam, hypergeometric Gaussian beam and Laguerre Gaussian beam. It is found that smaller mode numbers lead to less mode coupling. The same is partially observed for increasing source sizes. Comparing the vortex beams amongst themselves, it is seen that hypergeometric Gaussian beam is the one retaining the most power in intrinsic mode during propagation, but only at lowest mode index of unity. At higher mode indices this advantage passes over to the Gaussian vortex beam. (C) 2017 Elsevier Ltd. All rights reserved.