The Novel Plasmonics-Transition Metal Dichalcogenides Hybrid Nanostructures

Transition metal dichalcogenides (TMDs) are one of the hot research areas owing to their unique optoelectronic properties, which have been demonslidted for potential usage in light harvesting, photodetectors, phototransistors, lightemitting diodes, and nanolasers, etc. Few-layer TMDs are attractive because their band gaps are in the visible to nearinfrared region, their excitons have large binding energies and high oscillator strengths, and the inversion symmetry breaking in monolayer TMDs brings in valley-selective circular dichroism. Surface plasmons supported in metallic nanostructures can confine light in the subwavelength scale. The optical properties of surface plasmons, such as the resonance position, linewidth, near-field enhancement, and far-field radiation properties can be flexibly controlled by reasonable design. The combination of the plasmonic nanostructures and TMDs will advance the frontiers of nanophotonics and promote the applications of nanophotonic devices. In this paper, we review the state of the art research advances on hybrid plasmonics-TMDs structures. We first introduce the properties of propagating surface plasmon polaritons and localized surface plasmons, emphasizing on the property of the near field enhancement, which is the physical foundation of enhancing light-matter interaction in many nano-optics systems. Then, we briefly introduce the basic theoretical background of light-matter interaction and explicate the boundary between weak and strong coupling region. The next we introduce the basic lattice structure and atom composition of TMDs materials as well as the related optical properties, including the slicing excitonic effect at room temperature, valley-selective circular dichroism, and the defect-related single photon emission. Further, we introduce the recent experimental advances on plasmon-exciton coupling in the weak and strong coupling region. In the weak coupling region, the related research progress on surfaceenhanced spectroscopy including surface-enhanced nonlinear effect, Raman, photoluminescence, and the enhanced photocurrait effect have been introduced in detail. In the strong coupling region, we focus on the current research hotspots including single nanoparticle strong coupling, lattice structure strong coupling and the active control strong coupling devices. Finally, we make a prospect of future opportunities based on this novel hybrid material platform.