Dynamically Tunable Exciton-Photon Coupling via Multi-Physics Field in Transition Metal Dichalcogenide Microcavities.

Atomically thin transition-metal dichalcogenides (TMDs) host tightly bound excitons with large oscillator strengths, making them ideal for studying light-matter interactions and polaritonic devices. When integrated with optical microcavities, TMD monolayers and van der Waals heterostructures enable engineering of the local density of optical states (LDOS), giving rise to Purcell-enhanced emission in the weak coupling regime and exciton-polaritons in the strong coupling regime. Practical polariton devices require dynamic, reversible control of exciton-photon detuning and coupling strength, as these parameters determine Hopfield coefficients, dispersion, linewidth, relaxation dynamics, and nonlinear response. Unlike static microcavities, dynamic control enables exciton-polaritons to adapt to diverse operating conditions, allowing real-time functional switching and precise performance optimization. This strategy overcomes the inherent limitations of static control, such as limited functionality and adaptability. Recent advances have established several effective tuning strategies, including piezoelectric, electrical, thermal, and all-optical approaches, enabling control over polariton states and functions including energy tuning, polarization/valley-selective responses, and ultrafast optical modulation. This review summarizes these dynamic control strategies in microcavities and discusses key challenges and future directions toward scalable, stable, on-chip integrated polariton platforms.