Zhou Huixian, Cheng Jierong, Fan Fei, Wang Xianghui, Chang Shengjiang
Opt Express. 2021 Jan 18;29(2):1384-1395. doi: 10.1364/OE.413119.
Simultaneous control of phase and polarization offers a large degree of freedom to tailor the beam properties, for instance, enabling generation of structured beams such as vector beams and vector vortex beams. Here, we propose an ultrathin freestanding metasurface operating at the terahertz frequency for efficient generation of vector vortex beam with an arbitrarily defined topological charge from linearly polarized excitation. The metasurface is composed of bilayer metallic patterns separated by a thin quartz slab, with one layer determining the transmission polarization and the other controlling the transmission phase. The tightly cascaded two layers form a Fabry-Perot cavity to maximize the efficiency of the polarization and phase control. Two metasurfaces for generation of radially polarized vector beam with uniform phase and vortex phase are fabricated and tested at 0.14 THz. The experimental results successfully demonstrate the generation of high-quality vector beams with the desired phase. In the experiment, the ultrathin and freestanding properties allow the metasurface to be easily combined with other components, which shows great potential for the development of various compact terahertz systems.
同时控制相位和偏振为定制光束特性提供了很大的自由度，例如，能够产生诸如矢量光束和矢量涡旋光束等结构化光束。在此，我们提出一种工作在太赫兹频率的超薄独立超表面，用于从线偏振激发高效产生具有任意定义拓扑电荷的矢量涡旋光束。该超表面由被薄石英板隔开的双层金属图案组成，其中一层决定透射偏振，另一层控制透射相位。紧密级联的两层形成一个法布里 - 珀罗腔，以最大化偏振和相位控制的效率。制作了两个用于产生具有均匀相位和涡旋相位的径向偏振矢量光束的超表面，并在0.14太赫兹下进行了测试。实验结果成功证明了能够产生具有所需相位的高质量矢量光束。在实验中，超薄和独立的特性使超表面能够轻松与其他组件组合，这显示出在各种紧凑型太赫兹系统开发方面的巨大潜力。
