完美涡旋光的自由空间传播特性

理想完美涡旋光束是一种光强分布不随拓扑荷数的改变而改变的特殊光束，与普通涡旋光束相比，其可以大幅提升在微粒操纵、光纤传输等方面的应用效率。为了探究完美涡旋光束的自由空间传播特性，利用汉克变换详细计算并分析了拓扑荷数、初始面光环半径以及环宽度对其衍射特性的影响，发现完美涡旋光束不具备无衍射特性，光环会随着衍射距离的增加而展宽并逐渐向贝塞尔函数转变。当初始面光环半径增加或环宽度减小时，衍射效应增强，其中环宽度的影响要大于光环半径。与前两者相比，拓扑荷数对衍射效应的影响较小。研究结果对完美涡旋光的进一步应用提供了有益的理论参考。

Free space propagation characteristics of perfect vortex beam

The ideal perfect vortex beam is a special beam whose intensity distribution does not change with the change of the topological charge. Compared with ordinary vortex beam, it can greatly improve the application efficiency in particle manipulation and optical fiber transmission. In order to explore the free space propagation characteristics of the perfect vortex beam, this article uses Hank transformation to calculate and analyze the effects of the topological charge, the initial surface ring radius and the ring width on its diffraction characteristics in detail, it is found that the perfect vortex beam does not have the characteristic of non-diffraction, and the halo will broaden with the increase of the diffraction distance and gradually transform to the Bessel function. When the radius of the initial surface increases or the width of the ring decreases, the diffraction effect increases, and the effect of the ring width is greater than the ring radius. Compared with the previous two cases, the topological charge has less influence on the diffraction effect. The research in this paper is expected to provide a useful theoretical reference for the further application of the perfect vortex beam.