Research efforts of cavity quantum electrodynamics have focused on the manipulation of matter hybridized with photons under the strong coupling regime1,2,3. This has led to striking discoveries including polariton condensation2 and single-photon nonlinearity3, where the phonon scattering plays a critical role1,2,3,4,5,6,7,8,9. However, resolving the phonon scattering remains challenging for its non-radiative complexity. Here we demonstrate nonlinear phonon scattering in monolayer MoS2 that is strongly coupled to a plasmonic cavity mode. By hybridizing excitons and cavity photons, the phonon scattering is equipped with valley degree of freedom and boosted with superlinear enhancement to a stimulated regime, as revealed by Raman spectroscopy and our theoretical model. The valley polarization is drastically enhanced and sustained throughout the stimulated regime, suggesting a coherent scattering process enabled by the strong coupling. Our findings clarify the feasibility of valley–cavity-based systems for lighting, imaging, optical information processing and manipulating quantum correlations in cavity quantum electrodynamics2,3,10,11,12,13,14,15,16,17.
Subscribe to Journal
Get full journal access for 1 year
only $4.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Sanvitto, D. & Kéna-Cohen, S. The road towards polaritonic devices. Nat. Mater. 15, 1061–1073 (2016).
Deng, H., Haug, H. & Yamamoto, Y. Exciton-polariton Bose-Einstein condensation. Rev. Mod. Phys. 82, 1489–1537 (2010).
Lodahl, P., Mahmoodian, S. & Stobbe, S. Interfacing single photons and single quantum dots with photonic nanostructures. Rev. Mod. Phys. 87, 347–400 (2015).
Kasprzak, J., Solnyshkov, D. D., André, R., Dang, L. S. & Malpuech, G. Formation of an exciton polariton condensate: thermodynamic versus kinetic regimes. Phys. Rev. Lett. 101, 146404 (2008).
Müller, K. et al. Ultrafast polariton-phonon dynamics of strongly coupled quantum dot-nanocavity systems. Phys. Rev. X 5, 031006 (2015).
Seidelmann, T. et al. Phonon-induced enhancement of photon entanglement in quantum dot-cavity systems. Phys. Rev. Lett. 123, 137401 (2019).
Gonzalez-Ballestero, C., Feist, J., Gonzalo Badía, E., Moreno, E. & Garcia-Vidal, F. J. Uncoupled dark states can inherit polaritonic properties. Phys. Rev. Lett. 117, 156402 (2016).
Skopelitis, P., Cherotchenko, E. D., Kavokin, A. V. & Posazhennikova, A. Interplay of phonon and exciton-mediated superconductivity in hybrid semiconductor-superconductor structures. Phys. Rev. Lett. 120, 107001 (2018).
Thomas, A. et al. Exploring superconductivity under strong coupling with the vacuum electromagnetic field. Preprint at https://arxiv.org/abs/1911.01459 (2019).
Chen, Y.-J., Cain, J. D., Stanev, T. K., Dravid, V. P. & Stern, N. P. Valley-polarized exciton-polaritons in a monolayer semiconductor. Nat. Photon. 11, 431–435 (2017).
Dufferwiel, S. et al. Valley addressable exciton-polaritons in atomically thin semiconductors. Nat. Photon. 11, 497–501 (2017).
Sun, Z. et al. Optical control of room-temperature valley polaritons. Nat. Photon. 11, 491–496 (2017).
Chervy, T. et al. Room temperature chiral coupling of valley excitons with spin-momentum locked surface plasmons. ACS Photon. 5, 1281–1287 (2018).
Lundt, N. et al. Optical valley Hall effect for highly valley-coherent exciton-polaritons in an atomically thin semiconductor. Nat. Nanotechnol. 14, 770–775 (2019).
Zhu, H. et al. Observation of chiral phonons. Science 359, 579–582 (2018).
Miller, B. et al. Tuning the Fröhlich exciton-phonon scattering in monolayer MoS2. Nat. Commun. 10, 807 (2019).
Luo, Y. et al. Deterministic coupling of site-controlled quantum emitters in monolayer WSe2 to plasmonic nanocavities. Nat. Nanotechnol. 13, 1137–1142 (2018).
Liu, W. et al. Strong exciton–plasmon coupling in MoS2 coupled with plasmonic lattice. Nano Lett. 16, 1262–1269 (2016).
Chikkaraddy, R. et al. Single-molecule strong coupling at room temperature in plasmonic nanocavities. Nature 535, 127–130 (2016).
Mak, K. F. & Shan, J. Photonics and optoelectronics of 2D semiconductor transition metal dichalcogenides. Nat. Photon. 10, 216–226 (2016).
Carvalho, B. R. et al. Intervalley scattering by acoustic phonons in two-dimensional MoS2 revealed by double-resonance Raman spectroscopy. Nat. Commun. 8, 14670 (2017).
Xu, X., Yao, W., Xiao, D. & Heinz, T. Spin and pseudospins in layered transition metal dichalcogenides. Nat. Phys. 10, 343–350 (2014).
Zhang, X. et al. Phonon and Raman scattering of two-dimensional transition metal dichalcogenides from monolayer, multilayer to bulk material. Chem. Soc. Rev. 44, 2757–2785 (2015).
Drapcho, S. G. et al. Apparent breakdown of Raman selection rule at valley exciton resonances in monolayer MoS2. Phys. Rev. B 95, 165417 (2017).
Lombardi, A. et al. Pulsed molecular optomechanics in plasmonic nanocavities: from nonlinear vibrational instabilities to bond-breaking. Phys. Rev. X 8, 011016 (2018).
Schmidt, M. K., Esteban, R., González-Tudela, A., Giedke, G. & Aizpurua, J. Quantum mechanical description of Raman scattering from molecules in plasmonic cavities. ACS Nano 10, 6291–6298 (2016).
Fainstein, A. & Jusserand, B. Cavity-polariton mediated resonant Raman scattering. Phys. Rev. Lett. 78, 1576–1579 (1997).
Shalabney, A. et al. Enhanced Raman scattering from vibro-polariton hybrid states. Angew. Chem. Int. Ed. 54, 7971–7975 (2015).
Chen, S.-Y., Zheng, C., Fuhrer, M. S. & Yan, J. Helicity resolved Raman scattering of MoS2, MoSe2, WS2 and WSe2 atomic layers. Nano Lett. 15, 2526–2532 (2015).
Zhang, R. et al. Chemical mapping of a single molecule by plasmon-enhanced Raman scattering. Nature 498, 82–86 (2013).
Li, J. F. et al. Surface analysis using shell-isolated nanoparticle-enhanced Raman spectroscopy. Nat. Protoc. 8, 52–65 (2013).
Eilers, P. H. C. A perfect smoother. Anal. Chem. 75, 3631–3636 (2003).
Palik, E. D. Handbook of Optical Constants of Solids II (Academic Press, 1991).
Cadiz, F. et al. Excitonic linewidth approaching the homogeneous limit in MoS2-based van der Waals heterostructures. Phys. Rev. X 7, 021026 (2017).
Kleemann, M. E. et al. Strong-coupling of WSe2 in ultra-compact plasmonic nanocavities at room temperature. Nat. Commun. 8, 1296 (2017).
Qin, J. et al. Revealing strong plasmon-exciton coupling between nanogap resonators and two-dimensional semiconductors at ambient conditions. Phys. Rev. Lett. 124, 063902 (2020).
This work was supported by the King Abdullah University of Science and Technology Office of Sponsored Research award OSR-2016-CRG5-2996, National Science Foundation MRI grant 1725335 and the Ernest S. Kuh Endowed Chair Professorship. X.L. also acknowledges support from the National Natural Science Foundation of China (grant nos 12074297 and 62005202). J.-F.L. acknowledges support from National Natural Science Foundation of China (grant no. 21925404) and National Key Research and Development Program of China (2019YFA0705400). Y.-H.L. acknowledges support from the Ministry of Science and Technology (MoST 109-2124-M-007-001-MY3; 108-2112-M-007-006-MY3; 107-2923-M-007-002-MY3), the Frontier Research Center on Fundamental and Applied Sciences of Matters and the Center for Quantum Technology of National Tsing-Hua University.
The authors declare no competing interests.
Peer review information Nature Materials thanks Jeremy Baumberg and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Liu, X., Yi, J., Yang, S. et al. Nonlinear valley phonon scattering under the strong coupling regime. Nat. Mater. (2021). https://doi.org/10.1038/s41563-021-00972-x