Making Quantum Emitters Emit Vector Vortex Beams

Abstract

How far can we go in shaping the luminescence of quantum emitters? It is well known that by using cavities or nano-antennas, one can beam their luminescence into wellcontrolled directions of space. Here, we push this control to a level of complexity usually achieved with laser radiation: we make an assembly of colloidal quantum dots spontaneously emit vector vortex beams, which are swirls of light combining a non-zero angular momentum and an inhomogeneous field structure. The key ingredient to obtain this result is to increase the spatial coherence of the emitted photons. To fulfill this condition, we design and use plasmonic holograms that also impart a non-zero orbital angular momentum and a radial polarization state to the beam.