All-dielectric metasurfaces for generation and detection of multi-channel vortex beams

We theoretically investigate the generation and detection of multi-channel vortex beams (VBs) carrying multiple orbital angular momenta by a monolayer all-dielectric metasurface. The metasurface can realize simultaneous manipulation of a two-level amplitude and continuous phase by an artificial design. The multi-channel VBs' complex electric field is acquired by holography and the corresponding phase and amplitude are, respectively, encoded to the spatial orientation and geometry of nanofins. The maximum polarization conversion efficiency exceeds 98% and the uniformity is 0.0714. The ultra-compact, highly efficient and versatile metasurface is anticipated to promote development for high-capacity optical communication and integrated chip-level optical systems involving VBs. (C) 2019 The Japan Society of Applied Physics