Low-threshold lasing from bound states in the continuum with dielectric metasurfaces

Bound states in the continuum (BICs) with extremely large quality factors (Q factors) can enhance the light–matter interaction and thus achieve low-threshold lasing. Here, we theoretically propose and experimentally demonstrate the low-threshold lasing at room temperature based on BICs. A threshold of approximately 306.7 W/cm 2 (peak intensity) under a 7.5 ns-pulsed optical excitation is presented in an all-dielectric metasurface system consisting of titanium dioxide (TiO 2 ) nanopillars with a dye film. Also, the multimode lasing can be excited by the higher pumping. Our results may find exciting applications in on-chip coherent light sources, filtering, and sensing.