Controllable Plexcitonic Coupling in a WS₂-Ag Nanocavity with Solvents

Area of Science:

• Quantum optics
• Materials science
• Nanotechnology

Background:

• Strong coupling between emitters and cavities is key for quantum state control at room temperature.
• Two-dimensional transition metal dichalcogenides (TMDCs) show promise for strong coupling with plasmonic structures, but coupling strengths are limited and hard to control.

Purpose of the Study:

• To demonstrate active tuning of plexcitonic coupling strength in monolayer WS2 coupled to a plasmonic nanocavity.
• To explore the potential of solvent mixtures for controlling light-matter interactions in 2D materials.

Main Methods:

• Monolayer WS2 coupled to a plasmonic nanocavity was immersed in a mixed solution of dichloromethane (DCM) and ethanol.
• The mixture ratio was adjusted to continuously tune the plexcitonic coupling.
• Rabi splitting energy was measured across different mixture ratios.

Main Results:

• Continuous tuning of Rabi splitting energy was achieved, ranging from 183 meV in ethanol to 273 meV in DCM.
• The tuning is attributed to an increase in neutral exciton density in monolayer WS2 with higher DCM concentration.
• Demonstrated active control over plexcitonic coupling strength in a 2D material system.

Conclusions:

• Active tuning of plexcitonic coupling in monolayer WS2 is feasible using solvent mixtures.
• This method provides a pathway for further research into plexcitonic coupling in layered materials.
• Potential applications include quantum information processing and nonlinear optical materials.