Terahertz Semiconductor Vector Vortex Lasers

The growing demand for high-performance terahertz (THz) vortex beams in advanced imaging and high-capacity communications highlights the need for compact, integrated semiconductor vortex lasers, which have remained unrealized. Here, we demonstrate the first on-chip THz semiconductor vector vortex laser integrating a THz quantum cascade laser (QCL), a transmission waveguide, and a vortex-emitting ring resonator. The device transforms the QCL’s TM mode into a unidirectional whispering gallery mode (WGM), which is coherently extracted through periodically arranged dual-slit scatterers in the ring resonator to generate free-space vector vortex beams. The dual-slit design with air-bridge electrical pumping ensures unidirectional WGM propagation and loss compensation, achieving controllable topological charges, high mode purity, and milliwatt-level output. A representative device emits left- and right-handed circularly polarized vortex beams at 3.445 THz with topological charges of 1 and 3 and mode purities of 91.0% and 87.7%, respectively, and a total pulsed power of 6.2 mW. This work opens new opportunities for THz high-resolution imaging and orbital-angular-momentum–multiplexed communications.