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arXiv · 2609.07587

Encapsulated macroscopic WS$_2$ monolayers enable room-temperature exciton-polariton lattices

Abstract

Large-area, optically homogeneous monolayer semiconductors are a critical prerequisite for scalable room-temperature polaritonics and for realizing polariton lattices extending across many unit cells. Yet, the small size, optical inhomogeneity, and device-to-device variability of conventional exfoliated flakes have remained major obstacles. Here, we overcome these limitations using 1-dodecanol-encapsulated WS$_2$ monolayers that combine millimeter-scale coverage with remarkably uniform optical properties over lateral distances approaching $300\,$$\mu \mathrm{m}$. Integrated into a tunable open microcavity, these monolayers exhibit robust room-temperature exciton-photon strong coupling, evidenced by a pronounced anti-crossing and a Rabi splitting of $\hbar \Omega_{\mathrm{R}} \approx 31\,\mathrm{meV}$. Leveraging the exceptional uniformity of this platform, we realize a two-dimensional polaritonic kagome lattice and directly resolve its characteristic band structure. Angle-resolved spectroscopy reveals Dirac dispersive bands together with a weakly dispersive flat-band-like branch within the $s$-band, in good agreement with a linear non-interacting model. Complementary momentum- and real-space imaging further identifies the associated bond-centered and site-centered mode profiles. These results establish large-area WS$_2$ monolayers in open microcavities as a scalable platform for engineering polariton band structures and exploring synthetic quantum materials under ambient conditions.

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Shiyu Huang, Sander Scheel, Jiang Qu, Johannes Düreth, Dominik Horneber, Edith Wietek, Simon Widmann, Libo Ma, Monika Emmerling, Martin Kamp, Simon Betzold, Alexey Chernikov, Sven Höfling, Sebastian Klembt. 2026-09-07. Encapsulated macroscopic WS$_2$ monolayers enable room-temperature exciton-polariton lattices. https://arxiv.org/abs/2609.07587

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