Engineering of the orbital angular momentum (OAM) of light due to interaction with photonic lattices reveals rich physics and motivates potential applications. We report the experimental creation of regularly distributed quantized vortex arrays in momentum space by probing the honeycomb and hexagonal photonic lattices with a single focused Gaussian beam. For the honeycomb lattice, the vortices are associated with Dirac points. However, we show that the resulting spatial patterns of vortices are strongly defined by the symmetry of the wave packet evolving in the photonic lattices and not by their topological properties. Our findings reveal the underlying physics by connecting the symmetry and OAM conversion and provide a simple and efficient method to create regularly distributed multiple vortices from unstructured light.

理论计算和数值模拟了一维周期性复式光子晶格中光的分叉无衍射传输现象。当晶格满足退化的SSH模型时，波矢为±π的入射光将分裂为两束完全相同的对称无衍射光，且分叉夹角可通过耦合系数J来调节；在此基础上，通过微扰波导作用引入了调制相位ϕ，当微扰满足宇称时间对称时，只要入射光波矢k与调制相位ϕ之和为±π便能实现任意入射光波的无衍射分叉传输。进一步研究表明，次近邻耦合作用可以调控两个无衍射分叉光束的传输角度及其分功比。本研究为光学开关及未来全光路的设计提供了理论指导。