  We harness the momentum of light resonating inside a micro-droplet cavity, to
experimentally generate micro-flows within the envelope of the drop. We 3D map
these optically induced flows by using fluorescent nanoparticles; which reveals
circular micro-streams. The flows are parametrically studied and, as expected,
exhibit an increase of rotation speed with optical power. The flow is
non-circular only when we intentionally break the axial symmetry of the
droplet. Besides the fundamental interest in light-flow interactions including
in opto-fluidic cavities, the optically controlled flows can serve in bringing
analytes into the maximum-power region of the microcavity.
