Strong photoluminescence enhancement from a WS₂ atomic layer integrated on a metallic nanogroove array with intermediate plasmon–exciton coupling

The coupling between surface plasmons and excitons in transition metal dichalcogenides (TMDs) plays crucial roles in light emission, nonlinear optics, and quantum information processing. However, the intermediate plasmon–exciton coupling has not been reported in the TMD-integrated metallic nanoarray. Herein, we demonstrate the intermediate coupling behavior between surface plasmons in the silver nanogroove array and excitons in 2D layered tungsten disulfide ( WS 2 ). The results show that the reflection spectra of the silver nanogroove array possess an obvious reflection dip at the wavelength of ∼630 nm due to the generation of surface plasmons. The experiment results are well consistent with the numerical simulations. When the silver nanoarray is integrated with a trilayer WS 2 , there exists a distinct coupling between surface plasmons and A excitons in WS 2 . The temporal coupled-mode theory analysis shows that the plasmon–exciton coupling locates in the intermediate plasmon–exciton coupling region. The intermediate coupling can give rise to the strong photoluminescence (PL) enhancement of 48-fold in WS 2 . The wavelength of the PL peak presents a red shift with the increase of the temperature. This work paves a new pathway for the generation of plasmon–exciton coupling and the PL enhancement in atomic-layer TMDs.