Propagation Of A Stochastic Electromagnetic Vortex Beam And Non-uniformly Correlated Beam In Oceanic Turbulence

The coherence and polarization are two fundamental concepts in statistical optics to deal with observable quantity. The unified theory of coherence and polarization of a stochastic electromagnetic beam on propagation was presented by Wolf in2003.It said that the spectral degree of coherence and polarization are two closely related aspects, and we can discuss the spectral density, the spectral degree of coherence and the spectral degree of polarization of a stochastic electromagnetic beam whether propagating through deterministic media or random media by using a general method called the2×2electric cross-spectral density matrix. The unified theory of coherence and polarization has not only enriched the theory of optics, but also brought unique ingenuities into many aspects in statistical optics. This theory has some important applications. Most of the studies are assumed sources with so-called Gaussian Schell-model correlations where the typical correlation is uniform over the whole field. Recently, there has been substantial interest in investigating the properties of a new type of random beams with nonuniform correlations. Atmospheric optical turbulence is primarily caused by fluctuating temperature which can be understood easily so a lot of work has been done to discuss the properties of a stochastic electromagnetic laser beam on propagation in atmospheric turbulence.Oceanic turbulence is induced by temperature and salinity fluctuations, there has been some interests in the applications since a comprehensive model of salinity and temperature fluctuation for the ocean has been presented. In this paper, we study the propagation of a stochastic electromagnetic vortex beam and an electromagnetic non-uniformly correlated beam in the oceanic turbulence. The spectral density, the spectral degree of coherence and the spectral degree of polarization are investigated in detail.The dissertation is divided into four chapters:In Chapter1, we introduce the develop process of the unified theory of coherence and polarization. Analyzing the situation and trend at inland and abroad in the related field, we emphasize the motivation and significance of this dissertation. Then we introduce the theoretical basis and fundamental method used in our work.In Chapter2, we derive a general formula for the elements of cross-spectral density matrix of a stochastic electromagnetic vortex beam while propagating in the oceanic turbulence by using the extended Huygens-Fresnel integral with the help of the unified theory of coherence and polarization of stochastic electromagnetic beams. With the help of numerical calculations we have then studied the changes in the spectral density, the spectral degree of coherence and the spectral degree of polarization. It is shown that the normalized average intensity will be affected by the oceanic turbulence. The changes of the spectral degree of coherence are investigated as well. It is also interesting to find that the spectral degree of polarization of the isotropic source will tend to the same value as it has in the source plane after propagation in the oceanic turbulence over sufficiently long propagation distance.In Chapter3, an electromagnetic non-uniformly correlated beam passing through oceanic turbulence has been discussed. With the help of numerical calculations we have then studied the spectral density and the spectral degree of polarization of such a beam on propagation through oceanic turbulence. It is shown that the oceanic turbulence will affect the intensity self-focusing of such a beam. The spectral degree of polarization of such a beam on propagation through oceanic turbulence will also be affected.In Chapter4, We summarize the work which has been done and draw up a plan for the future work.