球面波干涉法测量拉盖尔-高斯光的轨道角动量

Measuring the orbital angular momentum of Laguerre-Gauss light by spherical wave interferometry

采用球面波的拉盖尔-高斯光(LG光)和平面波的基模高斯光干涉的方法,可观察到多叶螺旋的干涉图样,螺旋的叶数即是LG光的拓扑荷数,由拓扑荷数可知光子的轨道角动量.利用涡旋相位片产生拓扑荷数1~8的LG光,研究了光强比和偏振条件对干涉图样的影响.为获得高对比度的干涉图样,要求LG光和高斯光的偏振方向相同并且光强基本相等.球面波干涉法用于测量LG光的轨道角动量简单直观,与干涉光强空间分布的细节无关,因此对光强扰动和背景噪声不敏感.

When a spherical wave Laguerre-Gauss(LG)light interferes with a plane wave fundamental mode Gauss light,the multi-leaf helix interference pattern can be observed.The number of the helix leaves is the topological charge of LG light,which can be used to determine the orbital angular momentum of photons.In this paper,the measurement of the orbital angular momentum of LG light was realized by the interference of spherical LG light and plane wave fundamental mode Gauss light.The influence of light intensity ratio and polarization on the interference pattern was also studied.In order to obtain high-contrast interference pattern,the LG light and Gaussian light should have the same polarization direction and the same intensity.The interference method was simple and intuitive.It has nothing to do with the details of spatial distribution of the intensity of the interference light.Thus,it was insensitive to light intensity disturbance and background noise.