Recently, under the leadership of academician Zhuang Songlin, OECE of USST has made important progress in the control of terahertz orbital angular momentum in cooperation with Professor Hu Qing of MIT and Professor Gu min of Melbourne University of Australia. By introducing various anisotropic and orthogonal circular air arrays on metal thin films, the terahertz wave front control (helix phase) is achieved, and the terahertz beam with orbital angular momentum is obtained. By locally controlling the angle of each air gap to control the geometric phase, the arbitrary topological charge of orbital angular momentum and the terahertz OAM beam dependent on polarization / spin (left and right) are realized. Furthermore, by designing Archimedes helix array structure and introducing dynamic phase, polarization dependent terahertz OAM beams with non opposite topological charges are realized. The research work may have important applications in terahertz communication, particle manipulation and so on. The research achievement "managing terahertz plasma vortex based on geometric and dynamic phase" was published on advanced optical materials, a famous journal in the field of optical materials（ https://doi.org/10.1002/adom.201801328 ）The first author is Zang Xiaofei, associate professor, and the corresponding author is Zhu Yiming. The research has been supported by national 973 program, national key research and development program, national natural fund and other projects.

Terahertz OAM control based on geometric phase and dynamics