利用矢量波分析法对分数阶高阶贝塞尔涡旋光束(FBV)的电矢量特性进行了研究。在紧聚焦和非紧聚焦条件下,研究了拓扑荷(TCs)增量为0.1阶、拓扑荷从2.1增到3的过程中,Ex、Ey、Ez三个电场分量强度图的变化情况。进而对比分析了TCs值为整数阶和半整数阶FBV光束在由紧聚焦向非紧聚焦过渡过程中Ex分量强度的变化情况。数值模拟结果表明,紧聚焦和非紧聚焦情况下,三个分量的电场强度分布差异较大,其亮环圆对称性均遭到破坏;非紧聚焦情况下,Ex分量的圆对称性增强,而Ey、Ez分量与紧聚焦条件下的光强分布基本相同;在由紧聚焦向非紧聚焦过渡过程中,Ex分量整数阶TCs光束亮环圆对称性逐渐增强,而半整数阶TCs光束亮环结构基本不变,仅存在缩放关系。
The electric vector feature of fractional high-order Bessel vortex beam (FBV) is studied based on the vector wave analysis. Under the tightly focused and non-tightly focused conditions, the changes of three electric- field components of Ex, Ey and Ez are studied with the topological charges (TCs) from 2.1 to 3 in the increment of 0.1. Moreover, the E x component of the FBV beam with integer and half integer TCs are comparatively analyzed during the process of the imaging scheme from tightly focused to non-tightly focused conditions. Numerical simulation results show that there are obvious difference within the three electric-field components and the circular symmetry of the bright rings are all broken. Under the non-tightly focused conditions, the circular symmetry o{ Ex component intensity increases. However, the distribution of Ey and Ez components demonstrate same with that under the tightly focused conditions. The circular symmetry of the Ex component of integer TCs bright rings gradually increased during the process of the imaging scheme from tightly focused to non-tightly focused conditions.Different with those, the formation of the half-integer TCs bright rings patterns remain unchanged and only has a magnification velationship.