Atomically thin transition metal dichalcogenides (TMDs) possess a number of properties that make them attractive for realizing room-temperature polariton devices1. An ideal platform for manipulating polariton fluids within monolayer TMDs is that of Bloch surface waves, which confine the electric field to a small volume near the surface of a dielectric mirror2,3,4. Here we demonstrate that monolayer tungsten disulfide can sustain Bloch surface wave polaritons (BSWPs) with a Rabi splitting of 43 meV and propagation lengths reaching 33 μm. In addition, we show strong polariton–polariton nonlinearities within BSWPs, which manifest themselves as a reversible blueshift of the lower polariton resonance. Such nonlinearities are at the heart of polariton devices5,6,7,8,9,10,11 and have not yet been demonstrated in TMD polaritons. As a proof of concept, we use the nonlinearity to implement a nonlinear polariton source. Our results demonstrate that BSWPs using TMDs can support long-range propagation combined with strong nonlinearities, enabling potential applications in integrated optical processing and polaritonic circuits.

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S.K.C. acknowledges support from the NSERC Discovery and SPG Grant Programs and the Canada Research Chair in Hybrid and Molecular Photonics. F.B. acknowledges support from the FQRNT PBEEE scholarship programme. L.M. acknowledges financial support from the NSERC Discovery Grant. Work at the City University of New York was supported by the National Science Foundation (NSF) under the EFRI 2-DARE programme (EFMA-1542863) and NSF-ECCS-1509551 grant. A.F., D.B. and D.S. acknowledge ERC ElecOpteR grant no. 780757. S.K.C., F.B., D.B. and D.S. acknowledge support from the mixed Québec–Italy Sub-commission for Bilateral Collaboration.

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  1. Department of Engineering Physics, École Polytechnique de Montréal, Montréal, Quebec, Canada

    • Fábio Barachati
    • , Soroush Hafezian
    • , Ludvik Martinu
    •  & Stéphane Kéna-Cohen
  2. CNR - NANOTEC, Istituto di Nanotecnologia, Lecce, Italy

    • Antonio Fieramosca
    • , Dario Ballarini
    •  & Daniele Sanvitto
  3. Department of Physics, City College & Graduate Center of the City University of New York, New York, NY, USA

    • Jie Gu
    • , Biswanath Chakraborty
    •  & Vinod Menon
  4. INFN, Istituto Nazionale di Fisica Nucleare, Sezione di Lecce, Lecce, Italy

    • Daniele Sanvitto


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S.K.C., D.B. and D.S. conceived the project and F.B. designed the sample. The sample was fabricated by F.B., S.H., J.G. and B.C. under the supervision of L.M., S.K.-C. and V.M. Optical experiments were performed by F.B., A.F. and D.B. F.B. analysed the data and wrote the manuscript. Numerical calculations were performed by F.B. and S.K.C. All authors contributed to revising the manuscript and analysing the results. D.B., D.S. and S.K.C. coordinated the project.

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The authors declare no competing interests.

Corresponding authors

Correspondence to Dario Ballarini or Stéphane Kéna-Cohen.

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    Energy dispersion for varying fluence

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