Multifunctional Vortex Beam Generation by a Dynamic Reflective Metasurface.

In recent decades, metasurfaces have attracted considerable interest to generate vortex beams, that is, orbital angular momentum (OAM) carrying beams. However, the existing OAM metasurfaces are mostly fixed‐mode or with single function. Here a concept of multifunctional vortex beam generation is proposed, and is realized by a dynamic reflective metasurface which is capable of controlling the vortex beam spatiotemporally. The proposed metasurface has the ability to control OAM mode and to observe rotational Doppler effect. As proof of concept, it is presented that the proposed metasurface can generate an l = −1 or l = +1 OAM mode reconfigurable beam, and an l = +1 spinning OAM beam with rotational Doppler effect. Both simulated and measured results show the effectiveness of the proposed multifunctional OAM metasurface which has two different functionalities. The proposed multifunctional OAM metasurface may have potential applications in OAM multiplexing communications and harmonics manipulation by rotational Doppler effect. [ABSTRACT FROM AUTHOR]