Excitons in a transition-metal dichalcogenide (TMDC) monolayer can be modulated through strain with spatial and spectral control, which offers opportunities for constructing quantum emitters for applications in onchip quantum communication and information processing. Strain-localized excitons in TMDC monolayers have so far mainly been observed under cryogenic conditions because of their subwavelength emission area, low quantum yield, and thermal-fluctuation-induced delocalization. Herein, we demonstrate both generation and detection of strain-localized excitons in WS 2 monolayer through a simple plasmonic structure design, where WS 2 monolayer covers individual Au nanodisks or nanorods. Enhanced emission from the strain-localized excitons of the deformed WS 2 monolayer near the plasmonic hotspots is observed at room temperature with a photoluminescence energy redshift up to 200 meV. The emission intensity and peak energy of the strain-localized excitons can be adjusted by the nanodisk size. Furthermore, the excitation and emission polarization of the strain-localized excitons are modulated by anisotropic Au nanorods. Our results provide a promising strategy for constructing nonclassical integrated light sources, high-sensitivity strain sensors, or tunable nanolasers for future dense nanophotonic integrated circuits.

The investigation on the coherent coupling in the plasmon-TMDCs hybrid system is attracting great attention for its high tunability of the systematic components as well as for the potential applications on the nanophotonic devices. Abundant investigations of the plasmon−exciton hybrid system focused on the internal Rabi-type coupling from week coupling regime to strong coupling regime. Here, we demonstrate the Fano-type asymmetry in the open plasmon-exciton system both theoretically and experimentally. The theoretical framework based on the cavity electrodynamics (CQED) is first proposed to distinguish the Fanotype asymmetry from Rabi-type asymmetry. The former is due to the interference process, while the latter is due to the detuning of the plasmonic and excitonic resonances. The Fano-type interference process is found to enhance the lower energy branch (LEB) and reduce the higher energy branch (HEB), resulting in the Fano-type asymmetry in the output spectra, even at zero detuning. The theoretical predictions are confirmed through the layer-dependent and temperature-dependent measurements on the mono-and multilayer WSe 2 -plasmonic lattice system. We found that distinct from the Rabi-type process, where the internal plasmon−exciton coupling dominates, the Fano-type process is also highly dependent on the external excitations on the exciton and plasmon components. Our work sheds light on the Fano interference process in the plasmon−exciton coupled system and would boost the applications of novel two-dimensional plasmonic polaritonic devices in the field of ultrasensing or detection.

Transition metal dichalcogenides (TMDCs) have recently attracted growing attention in the fields of dielectric nanophotonics because of their high refractive index and excitonic resonances. Despite the recent realizations of Mie resonances by patterning exfoliated TMDC flakes, it is still challenging to achieve large-scale TMDC-based photonic structures with a controllable thickness. Here, we report a bulk MoS2 metaphotonic platform realized by a chemical vapor deposition (CVD) bottom-up method, supporting both pronounced dielectric optical modes and self-coupled polaritons. Magnetic surface lattice resonances (M-SLRs) and their energy-momentum dispersions are demonstrated in 1D MoS2 gratings. Anticrossing behaviors with Rabi splitting up to 170 meV are observed when the M-SLRs are hybridized with the excitons in multilayer MoS2. In addition, distinct Mie modes and anapole-exciton polaritons are also experimentally demonstrated in 2D MoS2 disk arrays. We believe that the CVD bottom-up method would open up many possibilities to achieve large-scale TMDC-based photonic devices and enrich the toolbox of engineering exciton-photon interactions in TMDCs.