Propagation characteristics of the perfect vortex beam in anisotropic oceanic turbulence

2020 ◽  
Vol 59 (32) ◽  
pp. 9956
Author(s):  
Zonghua Hu ◽  
Huilong Liu ◽  
Jing Xia ◽  
Aga He ◽  
Hongbo Li ◽  
...  
2021 ◽  
Vol 9 (4) ◽  
pp. 442
Author(s):  
Xinguang Wang ◽  
Le Wang ◽  
Shengmei Zhao

In this paper, we use two methods to research the propagation characteristics of a Hypergeometric-Gaussian (HyGG) vortex beam under oceanic turbulence. One is numerical calculation based on the Rytov approximation theory, where the theoretical detection probability equation of the HyGG vortex beam propagating through oceanic turbulence is derived. The other is numerical simulation based on random phase screens model of oceanic turbulence, where the influences generated by oceanic turbulence on the phase and intensity of the propagation beam as well as the propagation of the beam through several independent phase screens, kept at the same distance, have the same effect. The effects of oceanic turbulence parameters and initial beam parameters on the detection probability of the HyGG vortex beam at the receiver are discussed. The results of theoretical derivation are well in agreement with those of numerical simulation, which demonstrated that the numerical simulation method could effectively simulate the complex theoretical derivation. Both results show that with higher dissipation rate of kinetic energy per unit mass of fluid, smaller dissipation rate of mean-squared temperature and lower temperature-salinity contribution ratio comes the better detection probability. Meanwhile, a HyGG vortex beam with smaller topological charge and longer wavelength has a superior turbulent resistance property. It provides a promising way to estimate the propagation characteristics of the optical beams in an underwater environment.


2020 ◽  
Vol 49 (7) ◽  
pp. 20190452
Author(s):  
牛超君 Chaojun Niu ◽  
王晓斌 Xiaobin Wang ◽  
卢芳 Fang Lu ◽  
韩香娥 Xiang’e Han

2020 ◽  
Vol 49 (7) ◽  
pp. 20190452
Author(s):  
牛超君 Chaojun Niu ◽  
王晓斌 Xiaobin Wang ◽  
卢芳 Fang Lu ◽  
韩香娥 Xiang’e Han

2021 ◽  
Vol 9 (10) ◽  
pp. 1139
Author(s):  
Xinguang Wang ◽  
Le Wang ◽  
Shengmei Zhao

Based on the extended Huygens–Fresnel principle and the power spectrum of anisotropic oceanic turbulence, the analytical expressions of the average intensity and coherence properties of an off-axis hollow Gaussian-Schell model (OAHGSM) vortex beam propagating through anisotropic oceanic turbulence were derived. The effects of turbulent ocean and beam characteristic parameters on the evolution properties of the OAHGSM vortex beam were analyzed in detail. Our numerical simulation results showed that the OAHGSM vortex beam with a larger position factor is more focusable. Meanwhile, the OAHGSM vortex beam eventually evolves into a Gaussian-like beam after propagating through the anisotropic oceanic turbulent channel. The speed of this process can be accelerated by the decrease of the hollow order, topological charge, beam width, and transverse coherence width of the beam. The results also indicated that the normalized average intensity spreads more greatly and the spectral degree of coherence decays more rapidly for the smaller dissipation rate of the kinetic energy per unit mass of fluid, the smaller anisotropic coefficient, the smaller inner scale factor, the larger dissipation rate of the mean-squared temperature, and the higher temperature–salinity contribution ratio.


Author(s):  
Wei Wang ◽  
Ping Wang ◽  
Weina Pang ◽  
Yuting Pan ◽  
Yuanhao Nie ◽  
...  

2020 ◽  
Vol 49 (6) ◽  
pp. 20190370
Author(s):  
王明军 Mingjun Wang ◽  
张佳琳 Jialin Zhang ◽  
王姣 Jiao Wang

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sunxiang Pan ◽  
Le Wang ◽  
Wennai Wang ◽  
Shengmei Zhao

Abstract In this paper, we present an effective way for simulating oceanic turbulence channel on the beam carrying orbital angular momentum (OAM). The influence caused by oceanic turbulence channel on the phase and intensity of the propagation beam is equivalent to that the beam passing through several individual phase screens generated by power spectrum inversion method at regular intervals. A modified subharmonic compensation method is then further balance the phase screen for the losses of lower frequency components in the power spectrum inversion method. The feasibility is verified by the theoretical phase structure function and the propagation characteristics of an OAM beam in underwater environment. The results show that the phase structure function and the propagation characteristics of the OAM beam evaluated by the phase screen model all coincide with those theoretical results at high spatial frequency. Simultaneously, the low frequency components could be effectively compensated by the modified subharmonic method. With the increase of the subharmonic order and sample level, the performance evaluated by the phase screen model are closer to the theoretical ones. It has provided an effective way for simulating oceanic turbulence channel for the underwater optical communications.


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