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arXiv · 2503.18530

Tracking the photoinduced dynamics of a dark excitonic state in single-layer WS$_2$ via resonant Autler-Townes splitting

Angela Montanaro·Francesco Valiera·Francesca Giusti·Francesca Fassioli·Chiara Trovatello·Giacomo Jarc·Enrico Maria Rigoni·Fang Liu·Xiaoyang Zhu·Stefano Dal Conte·Giulio Cerullo·Martin Eckstein·Daniele Fausti
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Abstract

Excitons in a monolayer transition metal dichalcogenide (1L-TMD) are highly bound states characterized by a Rydberg-like spectrum of discrete energy levels. Among these, states with odd-parity are known as dark excitons due to selection rules, which make their stationary and transient characterization challenging using linear optical techniques. Here, we demonstrate that the dynamics of a 2p dark excitonic state in 1L-WS$_2$ can be directly retrieved by measuring the Autler-Townes splitting of bright states in a three-pulse experiment. The splitting of the bright 1s excitonic state, observed by detuning a mid-infrared control field across the 1s-2p transition, provides an accurate characterization of the 2p state. Following carrier photoinjection, we observe a qualitatively different dynamics of the 1s and 2p levels, which is indicative of symmetry-dependent screening and exciton-exciton interactions. These findings provide new insights into many-body effects in TMDs, offering potential avenues for advancing the next generation optoelectronics.

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Angela Montanaro, Francesco Valiera, Francesca Giusti, Francesca Fassioli, Chiara Trovatello, Giacomo Jarc, Enrico Maria Rigoni, Fang Liu, Xiaoyang Zhu, Stefano Dal Conte, Giulio Cerullo, Martin Eckstein, Daniele Fausti. 2025-03-24. Tracking the photoinduced dynamics of a dark excitonic state in single-layer WS$_2$ via resonant Autler-Townes splitting. https://doi.org/10.1103/j34b-hh1c

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