部分相干环状偏心光束通过海洋湍流的传输特性

Propagation characteristics of partially coherent decentred annular beams propagating through oceanic turbulence

推导出了部分相干环状偏心光束在海洋湍流中传输的平均光强和光束质心位置的解析表达式,并给出了最大光强位置满足的传输方程.研究发现:经足够长距离传输后,在自由空间中最大光强位置比光束质心更靠近传输z轴,并且其位置随着光束相干参数的增大而靠近传输z轴,随着光束偏心参数和遮拦比的增大而远离传输z轴.但是,在海洋湍流中最大光强位置趋于质心位置,并且海洋湍流的增强会加速最大光强位置趋于质心位置的进程.在海洋湍流中光束的相干性对光束传输特性的影响明显减小.另一方面,光束质心位置与光束的相干性、光束传输距离以及海洋湍流均无关系,并且光束质心位置随着光束偏心参数和遮拦比的增大而远离传输z轴.所得结果对工作于水下湍流环境中的部分相干环状偏心光束的应用具有重要意义.

The analytical expressions for the average intensity and the centroid position of partially coherent decentred annular beams propagating through oceanic turbulence are derived,and the propagation equation of the position of the maximum intensity is also given.Changes of the average intensity,the centroid position and the position of the maximum intensity of partially coherent decentred annular beams during propagation are studied in detail.It is shown that both in free space and in oceanic turbulence,the position of the maximum intensity moves to the propagation z-axis with increasing the propagation distance,and is kept unchanged when the propagation distance is large enough.Furthermore,in free space the position of the maximum intensity is closer to the propagation z-axis than to the centroid position when the propagation distance is large enough.The position of the maximum intensity is closer to the propagation z-axis with increasing the correlation parameter,and far from the propagation z-axis with increasing the decentered parameter and the obscure ratio.However,in oceanic turbulence the position of the maximum intensity is close to the centroid position when the propagation distance is large enough,and the evolution is speeded with increasing the strength of oceanic turbulence.The influence of the beam coherence on propagation characteristics decreases due to oceanic turbulence.On the other hand,the centroid position is independent of the beam coherence,the propagation distance and the oceanic turbulence.The centroid position is far from the propagation z-axis with increasing the decentered parameter and the obscure ratio.In addition,the hollow core of partially coherent decentred annular beams is filled up as the propagation distance increases,and the evolution is speeded with increasing the strength of oceanic turbulence.The results obtained in this paper are very useful for applications of partially coherent decentred annular beams in oceanic turbulence.