J_(0)相关径向偏振涡旋光束紧聚焦的空间相干特性

Spatial correlation properties of tightly focused J_(0)-correlated radially polarized vortex beams

为了研究J_(0)相关径向偏振涡旋光束深聚焦的相干特性,采用矢量德拜理论和相干理论,对聚焦场在光轴和焦平面上的相干特性进行了理论分析和数值仿真,取得相干度表达式和模拟数据。结果表明,在焦点区域的纵向相干度不但随着拓扑荷数n的增加而增大,而且还随着相干参量或者数值孔径dNA的增大而减小;在焦平面的横向相干度也随着拓扑荷数或者相干参量或者数值孔径的增大而减小;当n≥5或者dNA≤0.4时,纵向相干度在焦点附近约为1;这种相干度还存在相位异常点。这些研究结果对J_(0)相关矢量涡旋光束在许多领域的应用具有一定意义。

In order to study the spatial correlation properties of tightly focused J_(0)-correlated radially polarized vortex beam through a high numerical aperture d NA,the vectorial Debye diffraction theory and the coherence theory were adopted.After theoretical analysis and numerical simulation of the correlation characteristics of focused field on the optical axis and the focal plane,the expression and simulation data of coherence degrees were obtained.The results show that,the longitudinal coherence degrees in the focal region increase as the topological charge n increases,but it decrease as the coherence parameter or the numerical aperture d NA;The transverse coherence degrees in the focal plane decrease with the increase of the topological charge,coherence parameter or numerical aperture.When n≥5 or d NA≤0.4,the longitudinal coherence near the focal point approximately equals to 1.Further,the coherence degrees are shown to exhibit phase singularities.The results are of great significance to the application of J_(0)-correlated vector vortex beams in many fields.