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Reducing orbital angular momentum crosstalk of the Bessel Gaussian beam for underwater optical communications
摘要： We derive the analytical expressions of the probabilities for the signal and the crosstalk orbital angular momentum (OAM) states of a high order Bessel Gaussian beam used in underwater optical communications. Our numerical results show that the probabilities of the signal and crosstalk OAM states are effected by the propagation distance and the parameters of the oceanic turbulence. The receiver aperture can be used to reduce the probabilities of the crosstalk OAM states and the probability of the detected signal OAM states keeps almost unchanged. Our results may improve the quality of the optical communications system.
关键词： Bessel Gaussian beam,orbital angular momentum,oceanic turbulence,underwater optical communications
更新于2025-09-23 15:21:01
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Influence of anisotropic turbulence on the Second-order statistics of a general-type partially coherent beam in the ocean
摘要： We investigate detailedly evolution properties of the angular spread and propagation factor (?? 2-factor) of a general-type partially coherent beam with Schell-model correlator in anisotropic oceanic turbulence. According to the extended Huygens–Fresnel principle, analytical expressions for the second-order moments of Wigner distribution function (WDF) in anisotropic oceanic turbulence are derived. In order to measure the resistance of a general partially coherent beam to effects of anisotropic oceanic turbulence, we introduce deviation percentage of the normalized angular spread and ?? 2-factor respectively between the general-type partially coherent beam and conventional Gaussian Schell-model (GSM) beam. Numerical results show that influence of anisotropy on the angular spread and ?? 2-factor is less for a general-type partially coherent beam than a conventional GSM beam in oceanic turbulence. Besides, the initial beam parameters have a significant effect on the angular spread and ?? 2-factor of a general-type partially coherent beam. Our results may be useful for underwater communication.
关键词： General-type partially coherent beams,Statistical properties,Anisotropy,Oceanic turbulence
更新于2025-09-19 17:15:36
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Probability distribution of the orbital angular momentum mode of the ultrashort Laguerre-Gaussian pulsed beam propagation in oceanic turbulence
摘要： By introducing the orbital angular momentum (OAM) eigenfunctions of the pulsed beam and two-frequency mutual coherence function in oceanic turbulence, we establish the received probability distribution of OAM modes of the ultrashort Laguerre-Gaussian pulsed beam propagating through oceanic turbulence. Our results show that the higher rate of dissipation of kinetic energy per unit mass of fluid, larger inner scale, smaller ratio of temperature and salinity contributions to the refractive index spectrum, or lower dissipation rate of the mean-squared temperature will cause the smaller pulse duration by its full-width half-maximum. The pulse duration has a weak dependence on the OAM quantum number. In addition, the smaller OAM quantum number and the larger transmission distance cause the smaller pulse delay. Our results will be useful for vortex pulsed beam in the optical ocean communication and remote sensing.
关键词： Pulse,Vortex beams,Oceanic turbulence,Orbital angular momentum,Optical communication
更新于2025-09-19 17:15:36
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Effects of anisotropic oceanic turbulence on the propagation of the OAM mode of a partially coherent modified Bessel correlated vortex beam
摘要： We have studied the impacts of anisotropic turbulence on the orbital angular momentum (OAM) mode of a partially coherent modified Bessel correlated vortex beam propagation in an oceanic channel. In the weak turbulence paraxial channel, a new model of the probability density of OAM modes has been established. Effects of specific parameters of the oceanic turbulence on it have been studied, it is shown that there is an optimizing receiving aperture diameter in the specific interval of the ratio of temperature and salinity (cid:2) , which can reduce the effect of (cid:2) on the normalized energy weight of OAM modes and the reception of fluctuation signal. The effect of oceanic turbulence with higher anisotropy on the OAM signal is weaker than the turbulence possessing lower anisotropy. We can choose the mode carrying lower OAM quantum number to transfer information more efficiently, and we can utilize the OAM mode with large energy level difference between modes and so on to reduce mode interference and enhance the information capacity of optical communication links.
关键词： optical communication,partially coherent modified Bessel correlated vortex beam,propagation,OAM mode,anisotropic oceanic turbulence
更新于2025-09-04 15:30:14