Effect of anisotropy on intensity fluctuations in oceanic turbulence

Baykal, Yahya

doi:10.1080/09500340.2017.1404652

Cited by 24 publications

(8 citation statements)

References 37 publications

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“…Under weak fluctuation conditions, the scintillation index is approximately equal to the log-irradiance variance, i.e., m 2 = σ 2 ln I [37]. Previous studies [15,41] show that the scintillation index σ 2 ln I is strongly related to the log-amplitude variance σ 2 χ . The log-irradiance variance can be expressed as [42]…”

Section: Scintillation Index For Spherical Wave With Aperture Average...mentioning

confidence: 95%

“…In reality, oceanic turbulence exhibits asymmetric spatial frequencies in various directions, resulting in an anisotropic spatial power spectral density due to the rotation of the Earth [14]. The effect of anisotropic oceanic turbulence on the intensity fluctuations was discussed by Baykal [15,16]. Thereafter, the effect of anisotropic turbulence on the average bit error rate (BER) was further investigated when an asymmetrical Gaussian beam propagates in anisotropic turbulence [17].…”

Section: Introductionmentioning

confidence: 99%

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Scintillation Index for Spherical Wave Propagation in Anisotropic Weak Oceanic Turbulence with Aperture Averaging under the Effect of Inner Scale and Outer Scale

Lin

Zhang

et al. 2022

Photonics

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Due to the advantages of high transmission rate, lower power consumption, high security, etc., underwater wireless optical communication (UWOC) has been widely studied and considered as a potential technique for underwater communication. However, its performance is severely degraded by oceanic turbulence due to refractive index fluctuations, which is caused by the change of inhomogeneous ocean environment. Within our derived spatial power spectrum model under anisotropic oceanic turbulence, we conducted a detailed investigation for a spherical wave propagating in weak anisotropic turbulence in this paper. Based on the derived oceanic spectrum, we proposed a scintillation index model for spherical wave in anisotropic oceanic turbulence considering the aperture averaging effect at non-zero inner scale and limited outer scale. Besides, we analyze the aperture averaging scintillation index under the influence of channel parameters such as inner and outer scales. Simulation results reveal that the scintillation index increases with the increase of the outer scale, while the inner scale induces an opposite trend on the scintillation index. Moreover, the inner scale exhibits a larger impact than the outer scale on the UWOC system over weak oceanic turbulence.

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Section: Scintillation Index For Spherical Wave With Aperture Average...mentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Scintillation Index for Spherical Wave Propagation in Anisotropic Weak Oceanic Turbulence with Aperture Averaging under the Effect of Inner Scale and Outer Scale

Lin

Zhang

et al. 2022

Photonics

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“…As for an-isotropic oceanic turbulence, the power spectrum of refractive-index fluctuations is given by [32][33][34]…”

Section: Wave Structure Function Of Beam Wavesmentioning

confidence: 99%

Effects of Turbulence on the Vortex Modes Carried by Quasi-Diffracting Free Finite Energy Beam in Ocean

Liang

Zhang

Yang

2020

JMSE

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By developing new wave structure function of a beam waves, we derive the transmitting probability of signal vortex modes in oceanic turbulence based on Rytov approximation theory. Applying this transmitting probability of signal vortex modes, we study the influence of oceanic turbulence on the transmittance of the vortex modes carried by Mathieu-Gaussian beam. This model shows the transmitting probability of Mathieu-Gaussian beam with narrow initial beam width, long wavelength, and small ellipticity parameter is higher than the transmitting probability of the signal vortex modes in case of the beam with wide initial beam width, short wavelength, and great ellipticity parameter. Furthermore, when Mathieu-Gaussian beam has a suitable semi-cone angle, the effect of weak-turbulence channel on the transmitting probability of signal vortex modes with different topological charge can be ignored. Mathieu-Gaussian beam is a more suitable carrier for high information channel of underwater wireless optical communication than Laguerre-Gaussian beam.

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“…Many studies have shown that the atmospheric turbulence [19,[29][30][31] as well as the underwater [32,33] are anisotropic. Recently, many papers have been published about the effects of anisotropic underwater turbulence on the optical communication systems [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48].…”

Section: Introductionmentioning

confidence: 99%

Study of anisotropy of convective optical underwater turbulence and the effect of the mean water temperature in the presence of a varying temperature gradient on it

Razi¹,

Shokoohi²,

Rasouli³

2022

Laser Phys.

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In this paper, the anisotropy of optical convective underwater turbulence is investigated in terms of the variance of angle of arrival (AOA) fluctuations of a narrow laser beam propagating through it in different sections of the medium. The collimated laser beam with a wavelength 532 nm and a diameter 1 cm, which passes through a convective underwater turbulence. The turbulence is generated in a water tank with dimensions of 20 cm × 36 cm × 20 cm, which is installed on a flat surface electrical heater. During the experiments, the mean water temperature (MWT) can be changed from room temperature to 34 ∘C by increasing the heater temperature. The use of the heater also generates a temperature gradient in the medium. The laser beam propagates along a horizontal path with a length of 20 cm inside the tank at different altitudes from the heater source, as well as at different distances from one of the side walls of the turbulent medium. After passing the laser beam through the turbulent medium, the fluctuations of the AOA components in the vertical and horizontal directions are measured. From the time series of the measured AOA fluctuations, their variances are determined. The anisotropy of the medium is investigated by comparing the variance of AOA components measured in the vertical and horizontal directions. We show that the variances of both of vertical and horizontal components of the AOA fluctuations are increased with the MWT, and they are saturated at higher MWTs. In addition, different anisotropic behaviors are observed for the variances of the measured AOA fluctuations at the vicinity of the lateral wall and upper surface of the water. At the vicinity of the lateral wall the variances of the AOA fluctuations in the horizontal component are larger, but at the vicinity of the upper surface the variances of the AOA fluctuations in the vertical component are dominant. This behavior may be caused by the change of the convection motion direction in the turbulent fluid.

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Effect of anisotropy on intensity fluctuations in oceanic turbulence

Cited by 24 publications

References 37 publications

Scintillation Index for Spherical Wave Propagation in Anisotropic Weak Oceanic Turbulence with Aperture Averaging under the Effect of Inner Scale and Outer Scale

Scintillation Index for Spherical Wave Propagation in Anisotropic Weak Oceanic Turbulence with Aperture Averaging under the Effect of Inner Scale and Outer Scale

Effects of Turbulence on the Vortex Modes Carried by Quasi-Diffracting Free Finite Energy Beam in Ocean

Study of anisotropy of convective optical underwater turbulence and the effect of the mean water temperature in the presence of a varying temperature gradient on it

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