Propagation Characteristics Of Non-uniformly Correlated Blue-green Laser Beams In Ocean Turbulence

In recent years,a non-uniformly correlated laser beam with spatially varying correlation characteristics has some novel propagation characteristics.When the laser beam is propagated in seawater,ocean turbulence is an important influencing factor.Studies have shown that the propagation loss of the blue-green laser in seawater is small.Therefore,combining the characteristics of the non-uniformly correlated laser beam and the blue-green laser,establish the non-uniformly correlated blue-green laser beam propagation model in the ocean turbulence,research the propagation characteristics of non-uniformly correlated blue-green laser beam propagation in ocean turbulence are of important significance.This thesis focuses on the transmission characteristics of three non-uniformly correlated blue-green laser beam models in ocean turbulence,the main work is as follows:1.According to the generalized Huygens-Fresnel principle,the propagation models of non-uniformly Gaussian,non-uniformly Sinc and high-order non-uniformly Sinc correlated blue-green laser beams in ocean turbulence are established.The variation characteristics of the degree of coherence and cross-spectral density of the three non-uniformly correlated blue-green laser beams in the source plane are discussed.The influence of ocean turbulence on the intensity and lateral shifted intensity maximum of the three non-uniformly correlated blue-green laser beams is studied.The research shows that the degree of coherence of the three non-uniformly correlated blue-green laser beams is related to the horizontal coordinate.With the increase of the propagation distance,ocean turbulence suppresses its intensity.2.When the strength of ocean turbulence is constant,the effect of ocean turbulence on the intensity of non-uniformly Gaussian and non-uniformly Sinc correlated blue-green laser beams is studied.When the transmission distance is constant,the effects of the rate of dissipation of mean-square temperature,the rate of dissipation of kinetic energy,and the relative strength of temperature and salinity fluctuations on the intensity and lateral shifted intensity maximum are discussed separately.The research shows that the intensity distribution of the two non-uniformly correlated blue-green laser beams has an abrupt phenomenon near the source plane,and the ocean turbulence has a serious effect on the inhomogeneity of intensity distribution.The effect of different ocean turbulence parameters on the intensity and lateral shifted intensity maximum are obviously different.3.When the strength of ocean turbulence is constant,the influence of transmission distance and order on high-order non-uniformly Sinc correlation blue-green laser beam is studied.Studies have shown that as the order increases,the abrupt phenomenon of the intensity distribution disappears,and the beam transmission quality deteriorates.Through the above three aspects,this thesis studies the influence of ocean turbulence on the propagation characteristics of three non-uniformly correlated blue-green laser beams.The research results provide a theoretical basis for laser underwater transmission.