Perfect vortex beam with polarization-rotated functionality based on single-layer geometric-phase metasurface.

Abstract

Perfect vortex (PV) beam has seen significant advances in fields like particle manipulation, optical tweezers, and particle trapping, due to the fact that its ring radius is independent of the topological charge. Although geometric-phase metasurfaces have been proposed to generate PV beams, it always relies on circularly or elliptically polarized incident light, which hinders the miniaturization of compact optical devices. Here, using orthogonal decomposition of polarization vectors (ODPV), we proposed a geometric-phase metasurface, which breaks the dependence of circular polarization, to generate PV beam. In the design of the metasurface, we introduced PV phase profiles corresponding to the left-handed circularly polarized (LCP) component and the right-handed circularly polarized (RCP) component into the metasurface based on the principle of ODPV. We further determined the rotation angle of each nanostructure of the metasurface by calculating the argument of the composite vector of LCP and RCP in the transmission field. Simulation results show that the proposed geometric-phase metasurface can generate the PV beam upon the illumination of a linearly polarized incident. Moreover, the PV beam with polarization-rotated functionality is achieved by setting the polarization rotation angle. Furthermore, dual PV beams with orthogonal polarization states is realized at the same time by superimposing two sets of phase profiles on a single metasurface. It is also demonstrated that the PV beam parameters, such as ring radius and/or topological charge, can be set on demand in the metasurface design. The proposed metasurface has the exceptional advantage of high fabrication tolerance and is optical path miniaturization friendly, and will open a new avenue in advanced compact and integrated optical systems.