Generating multiple vortex beams simultaneously and independently in different directions by elaborately splicing multiple transmissive metasurfaces featuring polarization isolation

Abstract

In this paper, by elaborately splicing multiple transmissive metasurfaces (MSs) featuring polarization isolation, multiple linear polarized (LP) vortex beams are generated simultaneously and independently in different directions. Specifically, by carefully optimizing the radius of the array and the distance between the MS and array, each MS generates a well-performed deflection vortex beam with a low side-lobe level and little diffraction, resulting in a minor effect on other deflection vortex beams. Subsequently, four transmissive MSs are elaborately spliced, showing the polarization isolation characteristic between the adjacent MS, and thereby each MS is only illuminated by the respective antenna array. In addition, each MS only generates the desired LP vortex beam, and the corresponding cross-polarization is suppressed. Finally, the simulation and measurement results show that multiple LP vortex beams carrying different orbital angular momentum (OAM) modes are generated simultaneously and independently in different directions, verifying the effectiveness of the proposed method.