余弦高斯谢尔模涡旋光束在自由空间和海洋湍流中的统计特性

Statistical Properties of Cosine Gaussian Schell model Vortex Beams in Free Space and Oceanic Turbulence

利用广义惠更斯菲涅尔原理,推导出余弦高斯谢尔模涡旋光束在海洋湍流中传输的交叉谱密度函数表达式,并结合海洋空间功率谱模型函数,用数值模拟方法研究余弦高斯谢尔模涡旋光束在海洋湍流中的演变情况.结果表明:当光束在自由空间传输时,光束的光谱密度会逐渐自分裂为四束光,且在较短的传输距离内,每束光保持中心暗环,但随着传输距离的增大,暗环会逐渐消失;当光束在海洋湍流传输时,光束的光谱密度分布和相干度分布均会被湍流效应破坏.

In this paper,the analytical expressions for the cross spectral density of Cosine Gaussian Schell model Vortex(CGSMV)beams propagating through oceanic turbulence are derived by using the extended Huygens Fresnel principle.Combined with the spatial power spectrum of oceanic turbulence,the evolution behavior of CGSMV beams through oceanic turbulence is studied in detail by numerical simulation.It is shown that when the beams propagate in free space,the spectral density distribution gradually split into four beams and each individual lobe remains as the dark core at the short propagation distance.With the propagation distance increases,the dark core will gradually disappear.However,when the beams propagate in oceanic turbulence,both spectral density distribution and spectral degree of coherence distribution will be destroyed by turbulence effect.