Directional controllable terahertz orbital angular momentum generator

Most of previous reported orbital angular momentum (OAM) have limitations of unidirectional regulation. In order to expand the utilization of space resources in terahertz wave manipulation, we proposed a directional controllable terahertz OAM vortex beams generator, which can independently manipulate terahertz OAM vortex beams with transmission and reflection modes by external stimuli. When terahertz wave is incident along +/- z directions, the designed metasurface generates reflection and transmission modes vortex beams with topological charge of l = +/- 1, respectively. The simulated results are in good agreements with that of the theoretical predictions. Our work provides a new path to make full use of space resources and is expected to be applied in future high-capacity terahertz communication multiplexing system.