  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 subarray metasurfaces to multiplex optical
vortices in a single nano device, which in turn affects the compactness and
channel capacity of the device. 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 metaatom 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.
