涡旋光束拓扑荷值的柱面镜测量方法研究

Topological Charge Determination of Laguerre-Gaussian Beam using Cylindrical Lens

提出了一种利用柱面镜测量涡旋光束拓扑荷值的方法。首先,基于空间光调制器、利用计算全息法生成了拉盖尔-高斯（LG）涡旋光束;然后利用柱面镜对径向指数p=1,2,角向指数l=1~5的LG涡旋光束进行光束变换,实验结果表明：当涡旋光束通过柱面镜后,其中心暗核将发生劈裂,劈裂后的暗核数与涡旋光束的拓扑荷数值相等,以此实现拓扑荷值的测量。此外,为进一步验证该方法的准确性,利用涡旋光束与平面波干涉测量方法进行了对比分析;结果表明：基于柱面镜的涡旋光束拓扑荷值测量方法可有效测量LG涡旋光束的拓扑荷值;并且具有测试系统简单、光路调节简便的优点。

A method was proposed to determine the topological charge of the vortex beam using a cylindrical lens.First,an Laguerre Gaussian（ LG） vortex beam was produced using a spatial light modulator based on computer-generated holograms（ CGH）.A cylindrical lens was used to transform the LG vortex beams with indexes of p = 1,2 and l = 1 ～5,respectively.The experimental results show that when the vortex beam propagates through a cylindrical lens,the center of dark nucleus separated,and the topological charge is equal to the number of the dark nucleus.In order to verify the accuracy of this method,the LG vortex beam interferes with the plane wave which used to determine the TC of the LG beam.The results show that the topological charge value of LG vortex beam can be effectively measured by tlis method.