Zhong Jinzhan, Qi Shuxia, Liu Sheng, Li Peng, Wei Bingyan, Guo Xuyue, Cheng Huachao, Zhao Jianlin
Opt Lett. 2019 Aug 1;44(15):3849-3852. doi: 10.1364/OL.44.003849.
Optical vortices can evolve in light fields, of which the singularity evolution forms dark lines with complex topological structures, knotted or linked. We propose a method to more accurately and rapidly measure the topology of optical vortex fields. To accurately locate the phase singular points, phase measurement based on digital holography and, further, a numerical search algorithm, are utilized. A motor-driven right-angle prism enables the implementation of a single exposure of hologram for each measurement along the propagation direction, greatly improving the measurement speed. The three-dimensional (3D) spatial distributions of several typical vortex links and knots are experimentally reconstructed. The proposed method is expected to rapidly observe the 3D evolution of other complicated, or even vector, fields.
光学涡旋可在光场中演化，其奇点演化会形成具有复杂拓扑结构的暗线，这些暗线会打结或相互连接。我们提出了一种能更准确、快速地测量光学涡旋场拓扑结构的方法。为了精确地定位相位奇点，我们利用了基于数字全息术的相位测量以及进一步的数值搜索算法。一个电机驱动的直角棱镜能够沿着传播方向对每次测量实现全息图的单次曝光，极大地提高了测量速度。通过实验重建了几种典型涡旋链接和纽结的三维（3D）空间分布。预计所提出的方法能够快速观测其他复杂甚至矢量场的3D演化。
