Enhanced room-temperature stimulated emission in a WS₂-based plasmonic heterostructure

Transition metal dichalcogenides (TMDCs) offer tremendous prospects in the field of ultimate nanolasers due to their large exciton binding energies and atomic-scale thickness. The integration of TMDCs and plasmonic systems provides great potential for further miniaturization of device footprints. However, limitations in plasmon–exciton interactions and losses in plasmonic structures have restricted advancements in device performance. This study introduces a heterostructure that combines pretreated WS 2 with Au microplate gratings, which provides a low-loss platform that reduces non-radiative recombination. By optimizing the structural parameters, we enhance the coupling between excitons and surface plasmon polaritons (SPPs), effectively improving the coupling strength approximately threefold, which tends toward the strong coupling region. Furthermore, by utilizing the plasmonic bound states in the continuum (BIC), we achieve room-temperature stimulated emission amplification with nanosecond-pulsed pump powers exceeding 2.59 MW/cm 2 . Our findings provide a practical strategy for developing on-chip coherent light sources based on monolayer two-dimensional (2D) semiconductor–plasmonic structures, offering valuable insights into the interactions between plasmons and excitons.