A spatial-frequency patching metasurface enabling super-capacity perfect vector vortex beams

Abstract

Abstract Optical vortices, featured with an infinite number of orthogonal channels of orbital angular momentum, have demonstrated marvelous potentials in optical multiplexing and associated applications. However, conventional vortex beams with global phase modulation approach usually possess a single topological charge (TC) and a uniform radial distance with the donut-shaped intensity, leaving unlimited spatial intensity information unexplored. Here, to break the spatial capacity limitation, we introduce an entirely new concept of a spatial-frequency patching metasurface by patching the field distribution piece-by-piece in the spatial-frequency domain, thereby breaking the symmetry of the beam morphology and allowing for local manipulation of spatial intensity and TC distributions. Moreover, by superimposing two orthogonal circular polarized perfect VBs, our breakthrough offers a super-capacity with at least 13 channels across a 3D parametric space, including morphology, polarization azimuth and ellipticity angle, namely super-capacity perfect vector vortex beams (SC-PVVBs). Furthermore, we have designed an optimized Dammann grating to facilitate an array of SC-PVVBs, thereby unleashing the full potentials across 13 channels/bits for multi-dimensional complex information communications. Our findings promise dense data transmission in an ultra-secure manner using VBs, opening up new avenues in super-capacity optical information technology in an integrated metasurface platform.