Exciton-Polariton Dynamics in Two-Dimensional Materials

Exciton-polaritons arise when excitons in atomically thin semiconductors hybridise with confined photons, forming light–matter quasiparticles that inherit both strong nonlinearities and photonic coherence. Two-dimensional transition metal dichalcogenides and related van der Waals crystals exhibit tightly bound excitons with giant oscillator strengths, rendering them ideal platforms for exploring strong coupling phenomena at ambient conditions. Embedding these monolayers or heterostructures in optical resonators—ranging from Fabry–Pérot and photonic-crystal cavities to plasmonic nanocavities—yields Rabi splittings that can exceed tens of millielectronvolts. The resulting polariton dynamics manifest in ultrafast formation times, long-range propagation and pronounced nonlinear interactions governed by phase-space filling, exciton–exciton interactions and excitonic Rydberg states. Advances in multilayer stacking and patterned nanoresonators have enabled tunable coupling strengths, bright and dark polariton branches and enhanced valley coherence. These developments pave the way towards low-threshold polariton lasers, all-optical switches and quantum photonic circuits operating at room temperature. The interplay between cavity design, exciton binding energy and interlayer coupling continues to drive the field towards scalable, integrated polaritonic devices with applications in sensing, information processing and coherent light sources.

Research from Nature Portfolio

Recent studies have demonstrated systematic control of coupling strength in planar microcavities by embedding multiple monolayers of transition metal dichalcogenides. Incrementing the number of layers enhances vacuum Rabi splitting from tens to over seventy millielectronvolts, while time-resolved pump–probe measurements reveal that polariton interactions are dominated by phase-space filling and give rise to long-lived dark states. Investigations of excited excitonic Rydberg states in microcavities have further shown that higher-order excitons yield polaritons with nonlinear responses several times stronger than ground-state counterparts, opening routes to quantum nonlinear optics. In parallel, hybridisation of charged excitons (trions) with cavity modes has delivered pronounced Kerr-like nonlinearities at low photon flux, highlighting the promise of trion-polaritons for ultrafast, low-energy optical switching and quantum photonic circuitry.

Exciton-Polariton Dynamics in Two-Dimensional Materials publication trend

The graph below shows the total number of articles in exciton-polariton dynamics in two-dimensional materials across all publications each year (not limited to Nature Index journals).

Technical terms

Exciton: A Coulomb-bound pair of an electron and a hole forming a neutral quasiparticle in a semiconductor.

Polariton: A hybrid quasiparticle resulting from strong coupling between an exciton and a photon in an optical cavity.

Strong coupling regime: The interaction regime in which light–matter coupling strength exceeds the decay rates of excitons and photons, leading to energy level splitting.

Rabi splitting: The energy separation between the upper and lower polariton branches arising from strong light–matter interaction.

Van der Waals heterostructure: A stack of atomically thin layers held together by weak van der Waals forces, enabling bespoke electronic and optical properties.

References

1. Strong light-matter coupling in van der Waals materials. Light: Science & Applications (2024).
2. Exciton polariton interactions in Van der Waals superlattices at room temperature. Nature Communications (2023).
3. Recent progress of exciton transport in two-dimensional semiconductors. Nano Convergence (2023).
4. Two-dimensional semiconductors in the regime of strong light-matter coupling. Nature Communications (2018).
5. Exciton–polaritons in van der Waals heterostructures embedded in tunable microcavities. Nature Communications (2015).
6. Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer. Nature Communications (2016).
7. Photonic-crystal exciton-polaritons in monolayer semiconductors. Nature Communications (2018).
8. Two-Dimensional Metal–Chalcogenide Films in Tunable Optical Microcavities. Nano Letters (2014).
9. Excitons in atomically thin 2D semiconductors and their applications. Nanophotonics (2017).
10. Highly nonlinear trion-polaritons in a monolayer semiconductor. Nature Communications (2020).
11. Enhanced nonlinear interaction of polaritons via excitonic Rydberg states in monolayer WSe2. Nature Communications (2021).
12. Valley coherent exciton-polaritons in a monolayer semiconductor. Nature Communications (2018).