立方相位光栅用于光轨道角动量模式测量研究

Measurement of Optical Orbital Angular Momentum Mode Based on Cubic Phase Grating

本文提出一种使用立方相位光栅测量涡旋光束高阶轨道角动量(Orbital Angular Momentum,OAM)模式的方法。将艾里光束特有的相位变化特性与光栅的结构函数结合,设计一种立方相位光栅,并将涡旋光束准直入射至立方相位光栅的不同入射点上以产生衍射图。数值仿真和实验结果表明,通过分析衍射图中的类厄米-高斯衍射图样可以较容易地测量入射光束的OAM模式。入射光束拓扑荷值的大小由衍射图中的亮条纹数决定,其正负值由亮条纹的分布走向决定。优化后的实验链路可简化实验操作,效果明显,可将检测的拓扑荷值最高可达到60。

In this paper,we propose a method to measure the orbital angular momentum(OAM)modes of vortex beams using cubic phase gratings.Combining the unique phase change characteristics of the Airy beam with the structure function of the grating,a cubic phase grating is designed,and the vortex beam is collimated and incident on different incident points of the cubic phase grating to generate a diffraction pattern.The numerical simulation and experimental results show that the OAM mode of the incident beam can be easily measured by analyzing the HermiteGaussian diffraction pattern in the diffraction pattern.The topological charge of the incident beam is determined by the number of bright fringes in the diffraction pattern,and its positive and negative values are determined by the distribution trend of bright fringes.The optimized experimental link can simplify the experimental operation,the effect is obvious,and the topological load value detected can be reached up to 60.