  Orbital angular momentums (OAMs) of light can be categorized into
longitudinal OAM (L-OAM) and transverse OAM (T-OAM). Light carrying
time-varying L-OAM, known as self-torqued light, was recently discovered during
harmonic generation and has been extensively developed within the context of
optical frequency combs (OFCs). Meanwhile, ultrafast bursts of optical pulses,
analogous to OFCs, are sought for various light-matter interaction,
spectroscopic and nonlinear applications. However, achieving transiently
switchable T-OAM of light on request, namely spatiotemporal vortex pulse
bursts, with independently controlled spatiotemporal profile of each comb
tooth, remain unrealized thus far. In this work, the experimental generation of
spatiotemporal vortex bursts featured with controllable time-dependent
characteristics is reported. The resultant bursts comprised of spatiotemporal
optical vortex comb teeth have picosecond timescale switchable T-OAMs with
defined arrangement, manifesting as spatiotemporal torquing of light. We also
show ultrafast control of T-OAM chirality, yielding pulse bursts with staggered
azimuthal local momentum density, resembling K\'arm\'an vortex streets. This
approach enables the tailoring of more intricate spatiotemporal wavepacket
bursts, such as high-purity modes variation in both radial and azimuthal
quantum numbers of spatiotemporal Laguerre-Gaussian wavepackets over time,
which may facilitate a host of novel applications in ultrafast light-mater
interactions, high-dimensional quantum entanglements, space-time photonic
topologies as well as spatiotemporal metrology and photography.
