Monolithic integrated terahertz vector vortex quantum cascade laser

Lasers with orbital angular momentum (OAM) holds promise for compact, at-source solutions for applications in imaging and communications. In this work, we demonstrate an electrically pumped terahertz vector vortex quantum cascade laser, (THz-VV-QCL) which is fabricated by monolithically integrating a ring resonator with periodic double slits scattering elements, bus waveguide, and a distributed feedback QCL. To compensate for radiation and material losses, the ring resonator is pumped by the metallic air bridge. The mode purities of left/right-circularly polarized light are 87.7%/91%, respectively. The integrated THz-VV-QCL shows the great potential for application in THz communication and image.