Flexible generation of high-performance superposed perfect vortex beams with metasurfaces.

Vortex beams have been adopted as optical communications tools to improve the information capacity of free-space communication. Topological charge (TC) is a key parameter for analyzing vortex beams, specifically when defining wavelength division multiplexing and information coding capabilities. TC is typically proportional to the radial intensity profile and orbital angular momentum. The radial intensity profile of perfect vortex (PV) beams is TC-independent, thereby improving the efficiency of image processing and optical fiber transmission; however, PV beams generated in traditional ways are restricted in their degree of freedom for multiplexing and it can be difficult to distinguish PV beams with different TCs. Herein, we numerically simulate a single all-dielectric geometric metasurface to generate PV beams with intensity patterns corresponding to the TC. We increase the types of intensity modes by superposing specific polarization states of Laguerre–Gaussian beams, creating many options for optical communication transmission purposes. • We incorporated the superposition theory of Laguerre–Gaussian beams into the phase superposition formula of PV beams, and theoretically created a superposed PV beam. • The superposed PV beam has a great degree of freedom, and the superposition of different topological charges is reflected in the different number of light spots in the pattern. • We have designed a single geometric metasurface to simulate a four channel superposed PV beam, the metasurface can directly convert a common Gaussian beam into four different superposed PV beams. [ABSTRACT FROM AUTHOR]