Efficient Lasing in MoS ₂ /WSe ₂ -Based Metasurfaces Enabled by Quasi-Dark Magnetic Dipole Resonance

The combination of a strongly resonant optical metasurface (MS) with a MoS2/WSe2 heterobilayer is proposed for efficient free-space lasing enabled by the enhanced coupling between the optical and matter (exciton) states. The MS comprises silicon-rich nitride meta-atoms periodically arrayed in a subdiffractive lattice and overlaid with MoS2/WSe2, which provides an optically pumped gain around 1130 nm. Light emission is enabled by exploiting a quasi-bound state in the continuum in the form of a perturbed vertical magnetic dipole resonance. Following a meticulous design process guided by full-wave simulations and multipole expansion analysis, an ultralow lasing threshold of ∼6 kW/cm2 is achieved. Moreover, the thermal stability of the lasing structure is examined through heat-transfer simulations; stable operation with pump power densities up to a few MW/cm2 (3 orders of magnitude above the threshold) is predicted. These results demonstrate that MoS2/WSe2-based MS lasers can exhibit robust operation, paving the way for highly performing ultrathin light-emitting surfaces. The lasing response is rigorously assessed through a highly efficient temporal coupled-mode theory framework, verified by time-domain FEM simulations showing excellent agreement. Thus, an efficient and accurate approach to design and study MS lasers with arbitrary geometries and surface or bulk gain media is introduced, exhibiting significant advantages over cumbersome full-wave simulations.