Abstract
Nanophotonic platforms such as metasurfaces, achieving arbitrary phase profiles within ultrathin thickness, emerge as miniaturized, ultracompact and kaleidoscopic optical vortex generators. However, it is often required to segment or interleave independent sub-array metasurfaces to multiplex optical vortices in a single nano-device, which in turn affects the device’s compactness and channel capacity. Here, inspired by phyllotaxis patterns in pine cones and sunflowers, we theoretically prove and experimentally report that multiple optical vortices can be produced in a single compact phyllotaxis nanosieve, both in free space and on a chip, where one meta-atom may contribute to many vortices simultaneously. The time-resolved dynamics of on-chip interference wavefronts between multiple plasmonic vortices was revealed by ultrafast time-resolved photoemission electron microscopy. Our nature-inspired optical vortex generator would facilitate various vortex-related optical applications, including structured wavefront shaping, free-space and plasmonic vortices, and high-capacity information metaphotonics.
Highlights
The vortex is ubiquitous in nature, spanning from the galaxy, ocean flow, to phyllotaxis
As indicated by our theoretical insight, we prove that our phyllotaxis-inspired vortex nanosieve can generate multiple orbital angular momentum (OAM) beyond the topological charge of l
We have summarized the snapshots from the TR-photoemission electron microscope (PEEM) results under right-handed circular polarization (RCP) incidence which represent the three main stages of the vortex in dynamics formation, which are formation, revolution, and decay
Summary
The vortex is ubiquitous in nature, spanning from the galaxy, ocean flow, to phyllotaxis. Analogous to the natural vortex, such as tornado and whirlpool, the optical vortices (OVs) carrying OAM have helical phase fronts and. Jin et al eLight (2021) 1:5 meta-atoms to suppress cross coupling, which in turn degrades the device’s compactness and channel capacity. To deal with this problem, one may search therapies/solutions from either frequency domain or space domain. Elhanan Maguid et al [29] introduced asymmetric harmonic response geometric phase metasurface which realized OAM multiplexing through superposition of different harmonic components in the momentum space. We realize both freespace and near-field OAM multiplexing based on structure degeneracy in the space domain
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
