涡旋光束因为携带轨道角动量，在光通信、粒子操纵及量子信息等领域都具有重要的应用前景。目前有很多方法可用于产生涡旋光束，如利用螺旋相位板、模式转换、空间光调制器等。然而，传统的方法需要搭建体积相对较大的光学系统，限制了其在集成光学等领域中的应用。不同于传统方法中通过传输效应来获得相位变化，超表面可以通过纳米结构使入射光产生相位突变，在纳米尺度上独立控制动态或几何相位以产生涡旋。超表面具有强大光控制能力的同时，还具有体积小、易于集成等特点，因此成为了产生涡旋光的理想方法。文中在介绍产生涡旋光束基本原理的基础上，回顾了近年来利用超表面产生涡旋光束的研究进展。首先介绍了利用动力学相位、Pancharatnam-Berry (P-B)相位以及混合相位产生光学涡旋的方法。随后，对利用全息与编码超表面产生涡旋及通过多路复用产生多个涡旋等不同方法进行了综述。最后，对基于超表面产生涡旋的一些亟待解决的问题和应用前景作了简单总结与讨论。

A multipoint interferometer (MI), uniformly distributed point-like pinholes in a circle, was proposed to measure the orbital angular momentum (OAM) of vortex beams [Phys. Rev. Lett.101, 100801 (2008)PRLTAO0031-900710.1103/PhysRevLett.101.100801], which can be used for measuring OAM of light from astronomical sources. This is a simple and robust method; however, it is noted that this method is only available for low topological charge because the diffracted intensity patterns for vortex beams with higher OAM will repeat periodically. Here, we propose an improved multipoint interferometer (IMI) for measuring the OAM of an optical vortex with high topological charge. The structure of our IMI is almost the same as the MI, but the size of each pinhole is larger than a point in the MI. Such a small change enables each pinhole to get more phase information from the incident beams; accordingly, the IMI can distinguish any vortex beams with different OAM. We demonstrate its viability both theoretically and experimentally.

A gradient-index Reuleaux-triangle-shaped hole array was fabricated on germanium (Ge) by nanoimprint lithography and inductively coupled plasma processing as a broadband mid-infrared (IR) antireflective surface. The interaction between the {111} planes of cubic crystalline Ge and a circular mold successfully produced an orderly and periodically distributed Reuleaux-triangle-shaped hole array. As a result, the average transmittance increased 15.67% over the waveband at 3–12 μm and remained stable at the incidence angle of up to 60°. The vertices of the Reuleaux triangle showed local enhancement of the electric field intensities due to interference of the incident and reflected radiation fields. It was also found that nonuniform hole depths acted to modulate the transmittance over the 3–12 μm waveband.