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Propagation of the Bessel-Gaussian Beams Generated by Coherent Beam Combining in oceanic turbulence

Journal of Communications and Information Networks 2019年第3期4卷 25-37页

作者： Peng Yue Dongling Xu Xiang Yi State Key Laboratory of Integrated Service Networks Xidian UniversityXi’an 710071China

Coherent beam combining(CBC)is recently used to generate high power vortex beams which are strongly required in specific *** this paper,based on the extended Huygens-Fresnel principle,the exact theoretical forms for the intensity distribution of CBC Bessel-Gaussian beams(BGBs)in turbulent ocean are *** show the superiority of CBC BGBs in turbulent channels,the comparison in the intensity evolution of CBC BGBs with ideal BGBs is *** is found that the beam spreading of CBC BGBs is smaller than that of ideal BGBs under the same oceanic turbulence ***,the effect of the beam parameters and channel parameters on the quality of CBC BGBs is also *** results show that the oceanic turbulence with a higher rate of dissipation of kinetic energy per unit mass of fluid,lower dissipation rate of the mean-squared temperature,or smaller ratio of temperature and salinity contributions to the refractive index spectrum has smaller impact on CBC ***,the increasing number of the beamlets,the increasing waist width of each beamlet,and the decreasing radius of the beam distribution cause the optical energy to be more concentrated,and thus leading to a longer non-diffraction propagation distance.

关键词： CBC technology BGBs beam spreading oceanic turbulence

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Diffraction deep neural network based orbital angular momentum mode recognition scheme in oceanic turbulence

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Chinese Physics B 2023年第4期32卷 364-369页

作者：詹海潮陈兵彭怡翔王乐王文鼐赵生妹 Institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications(NUPT)Nanjing 210003China Key Laboratory of Broadband Wireless Communication and Sensor Network Technology(Ministry of Education) Nanjing University of Posts and TelecommunicationsNanjing 210003China

Orbital angular momentum(OAM)has the characteristics of mutual orthogonality between modes,and has been applied to underwater wireless optical communication(UWOC)systems to increase the channel *** this work,we propose a diffractive deep neural network(DDNN)based OAM mode recognition scheme,where the DDNN is trained to capture the features of the intensity distribution of the OAM modes and output the corresponding azimuthal indices and radial *** results show that the proposed scheme can recognize the azimuthal indices and radial indices of the OAM modes accurately and *** addition,the proposed scheme can resist weak oceanic turbulence(OT),and exhibit excellent ability to recognize OAM modes in a strong OT *** DDNN-based OAM mode recognition scheme has potential applications in UWOC systems.

关键词： orbital angular momentum diffractive deep neural network mode recognition oceanic turbulence

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Propagation Properties of Multi-Hyperbolic Sine-Correlated Beams in oceanic turbulence

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Optics and Photonics Journal 2022年第4期12卷 64-77页

作者： Chaoran Hu College of Science University of Shanghai for Science and Technology Shanghai China

As a new partially coherent beam, the propagation properties of the multi-hyperbolic sine-correlated (MHSC) beams in turbulent atmospheres have been studied. But as another important medium, the propagation properties of MHSC beams in oceanic turbulence. This paper has studied these questions in detail. The analytical formulas of spectral density and degree of coherence for the propagation are derived and the numerical simulations are represented. It is found that the intensity patterns of MHSC beams will evolve from dark-hollow profiles into Gaussian profiles caused by oceanic turbulence and will degenerate more rapidly with stronger oceanic turbulence. In addition, the coherence region becomes larger with decreasing in the dissipation rate of turbulence kinetic energy in unit mass liquid or increasing in the relative intensity of temperature and salinity fluctuations, mean square temperature dissipation rate. We also find that the degree of coherence of MHSC beams with a higher-order N will decrease more slowly than those of hyperbolic sine-correlated (HSC) beams.

关键词： Multi-Hyperbolic Sine-Correlated Beams oceanic turbulence Spectral Density Degree of Coherence Propagate

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Large-eddy simulation of the influence of a wavy lower boundary on the turbulence kinetic energy budget redistribution

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Journal of Oceanology and Limnology 2018年第4期36卷 1178-1188页

作者： LU Zongze FAN Wei LI Shuang GE Jianzhong Ocean College Zhejiang UniversityZhoushan 316000China State Key Laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai 200062China

oceanic turbulence plays an important role in coastal flow. However, as the effect of an uneven lower boundary on the adjacent turbulence is still not well understood, we explore the mechanics of nearshore turbulence with a turbulence-resolving numerical model known as a large-eddy-simulation model for an idealized scenario in a coastal region for which the lower boundary is a solid sinusoidal wave. The numerical simulation demonstrates how the mechanical energy of the current is transferred into local turbulence mixing, and shows the changes in turbulent intensity over the continuous phase change of the lower topography. The strongest turbulent kinetic energy is concentrated above the trough of the wavy surface. The turbulence mixing is mainly generated by the shear forces; the magnitude of shear production has a local maximum over the crest of the seabed topography, and there is an asymmetry in the shear production between the leeward and windward slopes. The numerical results are consistent with results from laboratory experiments. Our analysis provides an important insight into the mechanism of turbulent kinetic energy production and development.

关键词： large-eddy simulation wavy lower boundary oceanic turbulence nearshore

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Diagnostic of the diurnal cycle of turbulence of the Equatorial Atlantic Ocean upper boundary layer

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Natural Science 2011年第6期3卷 444-455页

作者： Udo T.Skielka Jacyra Soares Amauri P.Oliveira Jacques Servain Department of Atmospheric Sciences University of Sao PauloSao PauloBrazil Institut de Recherche pour le Developpement(IRD) ParisFrance

This work is an attempt to diagnose the turbu-lence field of the equatorial Atlantic Ocean dur-ing the dry period when the mixed layer is more highly developed using the General Ocean turbulence Model (GOTM). A relaxation scheme assimilates the vertical profiles of in situ ob-servations (current velocity, sea temperature and salinity) during simulations. In the absence of direct turbulence observations and modeling studies of the equatorial Atlantic Ocean, the results are compared qualitatively to observed and simulated results for the equatorial Pacific Ocean. Similarities are noted between the At-lantic simulation and previous studies per-formed in the Pacific Ocean. The mechanism of nocturnal turbulence production, namely deep- cycle turbulence, is well captured by GOTM si-mulations. This deep nocturnal turbulence ap-pears rather suddenly during the night in the simulations and consequently seems to be un-related to surface wind and radiation forcing.

关键词： oceanic Boundary Layer oceanic turbulence Tropical Oceanography Equatorial Atlantic Ocean

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