涡旋光束拓扑荷值的干涉测量方法

Topological Charges Measurement of Optical Vortex Beam by Interference Methods

基于平面波或球面波与拉盖尔-高斯(Laguerre-Gaussian,LG)涡旋光束的干涉特性,提出了一种LG涡旋光束拓扑荷值的测量方法。利用改进的马赫-曾德尔干涉光路对LG涡旋光束的拓扑荷值进行测量,其中,干涉光路中的一支为平面波或球面波,另一支为LG光束。然后,通过干涉亮条纹中的分叉数(平面波干涉时)或螺旋线嵌套数(球面波干涉时)来确定LG涡旋光束的拓扑荷值。拓扑荷值的符号,通过分叉向上还是向下(平面波干涉时)或螺旋线为顺时针还是逆时针(球面波干涉时)来判断其正负。数值模拟和试验结果表明:该方法能有效测量LG涡旋光束的拓扑荷值和符号,并且具有快速、简洁的特点。

Based on the interference properties between the Laguerre-Gaussian( LG) vortex beam and the plane wave or spherical wave,a measurement method was proposed,which was able to determine the topological charges( TCs) of LG vortex beam. A modified Mach-Zehnder interferometer was adopt to measure TCs of LG vortex beam. In this optical path,the plane wave or the spherical wave propagated was in one arm,and the LG beam propagated was in the other arm. Then,the TCs of the LG vortex beam were measured by counting the forks and spiral fringes in the interference patterns for the plane wave and spherical wave respectively.Moreover,the sign of the TCs could be determined by the fork directions( upward as positive,downward as negative) and the directions of spiral fringes( clockwise as positive,anticlockwise as negative) respectively.The numerical simulation and experimental results show that this method is effective to determine the topological charge and sign of LG beam quickly and conveniently.