大气湍流中部分相干径向偏振光束的光斑及偏振度研究

Research on Beam and Degree of Polarization of Partially Coherent Radially Polarized Beam in Turbulent Atmosphere

基于广义惠更斯理论及相干偏振统一理论,研究部分相干径向偏振光束在大气湍流中传输时,光源波长对光强分布,相干性、湍流强度、光斑尺寸及光源波长对偏振度(DOP)分布的影响。理论推导与数值模拟发现:部分相干径向偏振光束在大气湍流中传输时,光强分布受光源波长的影响明显,随着传输距离的增大,光强逐渐由空心分布演化为实心分布。光强完成这一演化所需的传输距离与光源波长有关,光源波长的减小,会造成光强由空心分布演化为实心分布所需的传输距离增大。另一方面,光束DOP分布也与相干性、大气湍流强度、光斑尺寸及光源波长相关,在确定的传输距离处,光源相干性越高、大气湍流越弱、光斑尺寸越大及光源波长越短,DOP随半径变化的曲线斜率也越大。随着光束传输距离的增加,这种趋势会逐渐突现。

Based on the theory of generalized Huygens theory and the unified theory of coherence and polarization, distribution of the intensity of partially coherent radially polarized beams influenced by source wavelength, and degree of polarization （DOP） influenced by coherence, atmosphere turbulence intensity, spot size and source wavelength, are investigated while propagating in turbulent atmosphere. It is shown that while the partially coherent radially polarized beams propagate in turbulent atmosphere, the distribution of intensity is affected by source wavelength obviously. With the increase of propagation distance, the doughnut beam spot of the partially coherent radially polarized beam becomes a solid beam, which is related to source wavelength. The shorter the source wavelength is, the longer distance the partially coherent radially polarized beam propagates to form a solid beam shape. In addition, distribution of DOP is also affected by coherence, atmosphere turbulence intensity, spot size and source wavelength. At a certain propagation distance, the rate of DOP with radius increases with the larger original coherence, the weaker atmosphere turbulence intensity, the bigger spot size and the shorter source wavelength. Such tendency becomes more obvious with longer propagation distance.