Controllable bound states in the continuum enabling blue-to-green directional vortex lasing

Bound states in the continuum (BIC) enable low-threshold lasing with high quality (Q) factors and polarization winding akin to vortices possessing integer topological charges. This BIC lasing action could be realized by conventional photonic crystal (PhC) cavities with embedded gain, but robust and deterministic control of BIC in momentum space remains challenging. Here, we report a monolithic visible BIC laser based on a hybrid cavity comprising an in-plane asymmetric distributed Bragg reflector (DBR), InGaN multiple quantum wells (MQWs) as the gain medium, and a square-lattice PhC slab. This hybrid cavity enhances light confinement, facilitating low-threshold lasing and high Q factors. By tuning the PhC lattice constant, BIC lasing modes are precisely controlled at specific k-space locations (on-Γ or off-Γ), allowing deterministic modulation of both the polarization winding and radiation directions of the vortex laser beams. Our work establishes a hybrid-cavity platform for engineering BIC in momentum space, offering a practical route toward spectrally tunable, directionally stable vortex lasers for visible-light applications such as optical trapping, structured illumination, and high-capacity communication.