Abstract In this paper, we propose a generalized kind of partially coherent vector beams with an off-axis vortex, named partially coherent radially polarized (PCRP) off-axis vortex beam for considering such a case in which laser beam passes through a spiral phase plate (SPP) but slightly deviates from the vortex core due to the experimental misoperation. The influences of such off-axis vortex phase on the focusing properties of the PCRP off-axis vortex beam after passing through a thin lens are theoretically investigated in detailed. It is found that the intensity pattern of the PCRP off-axis vortex beam possesses an additional dark core corresponding to the off-axis position of vortex core in the source plane, while it rotates gradually up to an angle of π ∕ 2 with respect to the initial displacement vector s as propagation distance increases for high spatial coherence, being qualitatively different from that of the on-axis vortex beam. However, such unique characteristics of the PCRP off-axis vortex beam will disappear in the case of a very low coherence. In addition, the vortex-induced changes of polarization start from its off-axis vortex core, which will be useful for the detection of a phase object as well as its vortex position in the application of optical detection technology. More importantly, our results show that, besides the topological charge and coherence length, the off-axis parameters of vortex phase play a great role in modulating the propagation properties, which provides an additional degree of freedom for focus shaping.

中文翻译：

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具有离轴涡旋的部分相干径向偏振光束

摘要 在本文中，我们提出了一种广义的具有离轴涡旋的部分相干矢量光束，称为部分相干径向偏振（PCRP）离轴涡旋光束，以考虑激光束穿过螺旋相位板的情况。 (SPP) 但由于实验误操作而略微偏离涡核。从理论上详细研究了这种离轴涡旋相位对PCRP离轴涡旋光束通过薄透镜后聚焦特性的影响。发现 PCRP 离轴涡旋光束的强度模式具有一个额外的暗核，对应于源平面中涡核的离轴位置，而随着传播距离的增加，它相对于初始位移矢量 s 逐渐旋转到 π ∕ 2 的角度，以实现高空间相干性，与轴上涡旋光束在性质上不同。然而，在相干性非常低的情况下，PCRP 离轴涡旋光束的这种独特特性将消失。此外，涡旋引起的偏振变化是从其离轴涡核开始的，这对于相位物体的检测及其涡旋位置在光学检测技术的应用中是有用的。更重要的是，我们的结果表明，除了拓扑电荷和相干长度外，涡旋相位的离轴参数在调制传播特性方面发挥着重要作用，这为焦点整形提供了额外的自由度。