Angularly Dispersed Vector Vortex Laser Generated by Exciton-Polariton Condensate in a Perovskite Microplatelet

Vector vortex beams with space-dependent phase distribution and polarization have been extensively studied for their various applications, such as optical imaging and communication. While conventional vortex beam lasers emit parallel light with phase singularities in real space, we here demonstrate a divergent vortex beam laser whose phase singularities are pinned to the featured azimuthal positions. The coherent beam was generated by the condensation of exciton-polaritons, hybrid quasi-particles from strongly coupled excitons and cavity-confined photons, in a CsPbBr₃ microplatelet. By means of polarization-resolved Michelson interferometry, we observed fork-like patterns that open toward opposite directions in the momentum-space images. FDTD simulations reveal that these patterns stem from the phase vortices of the divergent laser beam. Furthermore, polarization-dependent condensation patterns can be identified clearly through angle-resolved microphotoluminescence spectroscopy, showing the vector beam nature of our vortex lasers. These results demonstrate an approach for generating low-threshold, compact, and scalable single-mode vector vortex beam lasers.