Emerging as a family of waves, Janus waves are known to have “real” and “virtual” components under inversion of the propagation direction. Although tremendous interest has been evoked in vortex beams featuring spiral wavefronts, little research has been devoted to the vortex beam embedded Janus waves, i.e., Janus vortex beams. We propose a liquid crystal (LC) Pancharatnam–Berry (PB) phase element to demonstrate the realization of the Janus vortex beams and the modulation of the associated orbit angular momentum (OAM) and spin angular momentum (SAM). The generated Janus vortex beams show opposite OAM and SAM states at two distinct foci, revealing a spin-orbit interaction during propagation enabled by the LC PB phase element, which may play special roles in applications such as optical encryption and decryption. Other merits like reconfigurability and flexible switching between Janus vortex beams and autofocusing or autodefocusing vortex beams additionally increase the degree of freedom of manipulating vortex beams. This work provides a platform for tailoring complex structured light and may enrich the applications of vortex beams in classical and quantum optics.

针对涡旋光受大气湍流而产生的相位畸变问题，设计了卷积神经网络检测涡旋光束轨道角动量态。将相位畸变的拉盖尔高斯涡旋光光强图像作为样本数据输入，网络利用输入的数据集进行自主学习，经过多次迭代能够精确检测出光束高阶轨道角动量信息。仿真结果表明：在大气湍流强度不确定的情况下，模型对轨道角动量态范围为1~40、1~100、1~160的涡旋光束检测准确率分别为94%、90%、86%；在不同传输距离、不同径向指数、不同基模束腰半径以及不同波长下轨道角动量态范围为1~100的涡旋光束的检测准确率均达到78%以上，且具有很好的鲁棒性。该方法检测精度高、范围广、移植性强，可为涡旋光束轨道角动量态的检测与识别提供一种新思路。