PCELG光束通过光阑传输后偏振度的研究

Research of degree of polarization of PCELG beam propagating through a circular aperture

为了研究部分相干复宗量拉盖尔-高斯(PCELG)光束通过环形光阑后在湍流大气中传输时的偏振特性,基于拓展的惠更斯-菲涅耳原理,经理论推导,得出PCELG光束偏振度的解析表达式,并进行了相应的数值计算。结果表明,光阑的衍射效应将会造成PCELG光束偏振度振荡加剧的现象;当PCELG光束在湍流大气或自由空间中传输时,近轴处横向的偏振度有着剧烈的振荡,而在较远点处,其偏振度都是趋于1,且随着传输距离的增加,横向的偏振度趋于1时所对应的离轴距离也增大;当PCELG光束通过光阑后在自由空间中传输时,经过足够长的距离,偏振度将趋近于不同于初始偏振度的值,而在湍流大气中传输时,偏振度将趋近于初始偏振度。该结果对光束在大气中的传输及其应用具有实际意义。

To study the degree of polarization of partially coherent elegant Laguerre-Ganssian （PCELG） beam propagating through a circular aperture in turbulent atmosphere, based on extended Huygens-Fresnel principle, the formulas for the degree of polarization of PCELG beam were derived via theoretical calculation and the corresponding numerical calculation was carried out. The results indicate that the aperture diffraction effect will result in increasing oscillations of the polarization of PCELG beam. In turbulent atmosphere or in free space, the transverse degree of polarization near to the axis has a dramatic oscillation while the degree of polarization far from the axis approaches to 1. The further the propagation distance is, the larger the off-axis distance is. After propagating for a sufficiently long distance through the circular aperture in free space, the degree of polarization of PCELG beam approaches a value different from the initial one. However, it tends to the initial value in turbulent atmosphere. The results are useful for beam propagation and applications in atmosnhere.