  Toroidal vortex, a topological structure commonly observed in nature, exist
in various types such as bubbles produced by dolphins and the air flow
surrounding a flying dandelion. A toroidal vortex corresponds to a
spatiotemporal wave packet in the shape of a donut that propagates in the
direction perpendicular to the plane of the ring. In this work, we propose a
circular asymmetric grating to generate vortex rings. A cylindrical vector wave
packet is transformed by the device into a transmitted toroidal vortex pulse.
Such a compact toroidal vortex generator may find applications in optical
topology research and high-dimensional optical communications.
