Full-polarization-locked vortex beam generator with time-varying characteristics.

Vortex beams carrying orbital angular momentum (OAM) are considered to hold significant prospects in fields such as super-resolution imaging, high-capacity communications, and quantum optics. Therefore, the techniques of vortex beam generation have attracted extensive studies, in which the development of metasurfaces brings new vigor and vitality to it. However, the generation of reconfigurable vortex beams by metasurfaces at the incidence of arbitrary polarized electromagnetic (EM) waves holds challenges. In this study, an efficient and reconfigurable strategy utilizing PB phase-modulated circularly polarized waves and dynamic phase-modulated linearly polarized waves is proposed, enabling a polarization-locked fully polarization vortex beams generator. Based on this strategy, we designed and fabricated a prototype of the vortex beam generator for full polarization, which verifies the rotating Doppler effect and generates a time-varying vortex beam. All the results have been verified by simulation and measurements. In addition, the proposed strategy can be easily extended to other frequency regions and holds potential in areas such as information encryption, biosensing, and OAM multiplexing communication.