Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Real-space observation of vibrational strong coupling between propagating phonon polaritons and organic molecules

A Publisher Correction to this article was published on 04 December 2020

This article has been updated


Phonon polaritons in van der Waals materials can strongly enhance light–matter interactions at mid-infrared frequencies, owing to their extreme field confinement and long lifetimes1,2,3,4,5,6,7. Phonon polaritons thus bear potential for vibrational strong coupling with molecules. Although the onset of vibrational strong coupling was observed spectroscopically with phonon-polariton nanoresonators8, no experiments have resolved vibrational strong coupling in real space and with propagating modes. Here we demonstrate by nanoimaging that vibrational strong coupling can be achieved between propagating phonon polaritons in thin van der Waals crystals (hexagonal boron nitride) and molecular vibrations in adjacent thin molecular layers. We performed near-field polariton interferometry, showing that vibrational strong coupling leads to the formation of a propagating hybrid mode with a pronounced anti-crossing region in its dispersion, in which propagation with negative group velocity is found. Numerical calculations predict vibrational strong coupling for nanometre-thin molecular layers and phonon polaritons in few-layer van der Waals materials, which could make propagating phonon polaritons a promising platform for ultrasensitive on-chip spectroscopy and strong-coupling experiments.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Phonon-polariton interferometry of molecular vibrations.
Fig. 2: Real-space imaging of PPs on a h-BN–CBP layer in the region of anomalous dispersion.
Fig. 3: Dispersion and mode splitting.

Similar content being viewed by others

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors on reasonable request.

Change history


  1. Basov, D. N., Fogler, M. M. & García De Abajo, F. J. Polaritons in van der Waals materials. Science 354, aag1992 (2016).

    Article  Google Scholar 

  2. Low, T. et al. Polaritons in layered two-dimensional materials. Nat. Mater. 16, 182–194 (2017).

    Article  ADS  Google Scholar 

  3. Giles, A. J. et al. Ultralow-loss polaritons in isotopically pure boron nitride. Nat. Mater. 17, 134–139 (2018).

    Article  ADS  Google Scholar 

  4. Ma, W. et al. In-plane anisotropic and ultra-low-loss polaritons in a natural van der Waals crystal. Nature 562, 557–562 (2018).

    Article  ADS  Google Scholar 

  5. Zheng, Z. et al. Highly confined and tunable hyperbolic phonon polaritons in van der Waals semiconducting transition metal oxides. Adv. Mater. 30, e1705318 (2018).

    Article  Google Scholar 

  6. Yoxall, E. et al. Direct observation of ultraslow hyperbolic polariton propagation with negative phase velocity. Nat. Photon. 9, 674–678 (2015).

    Article  ADS  Google Scholar 

  7. Dai, S. et al. Tunable phonon polaritons in atomically thin van der Waals crystals of boron nitride. Science 343, 1125–1129 (2014).

    Article  ADS  Google Scholar 

  8. Autore, M. et al. Boron nitride nanoresonators for phonon-enhanced molecular vibrational spectroscopy at the strong coupling limit. Light Sci. Appl. 7, 17172–17178 (2018).

    Article  Google Scholar 

  9. Dai, S. et al. Graphene on hexagonal boron nitride as a tunable hyperbolic metamaterial. Nat. Nanotechnol. 10, 682–686 (2015).

    Article  ADS  Google Scholar 

  10. Kim, K. S. et al. The effect of adjacent materials on the propagation of phonon polaritons in hexagonal boron nitride. J. Phys. Chem. Lett. 8, 2902–2908 (2017).

    Article  Google Scholar 

  11. Fali, A. et al. Refractive index-based control of hyperbolic phonon-polariton propagation. Nano Lett. 19, 7725–7734 (2019).

    Article  ADS  Google Scholar 

  12. Dai, S. et al. Hyperbolic phonon polaritons in suspended hexagonal boron nitride. Nano Lett. 19, 1009–1014 (2019).

    Article  ADS  Google Scholar 

  13. Thomas, A. et al. Tilting a ground-state reactivity landscape by vibrational strong coupling. Science 363, 615–619 (2019).

    Article  ADS  Google Scholar 

  14. Herrera, F. & Owrutsky, J. Molecular polaritons for controlling chemistry with quantum optics. J. Chem. Phys. 152, 100902 (2020).

    Article  Google Scholar 

  15. Thomas, A. et al. Ground-state chemical reactivity under vibrational coupling to the vacuum electromagnetic field. Angew. Chem. Int. Ed. Engl. 128, 11634–11638 (2016).

    Article  Google Scholar 

  16. Ribeiro, R. F., Martínez-Martínez, L. A., Du, M., Campos-Gonzalez-Angulo, J. & Yuen-Zhou, J. Polariton chemistry: controlling molecular dynamics with optical cavities. Chem. Sci. 9, 6325–6339 (2018).

    Article  Google Scholar 

  17. Feist, J., Galego, J. & Garcia-Vidal, F. J. Polaritonic chemistry with organic molecules. ACS Photonics 5, 205–216 (2018).

    Article  Google Scholar 

  18. Rodrigo, D. et al. Mid-infrared plasmonic biosensing with graphene. Science 349, 165–168 (2015).

    Article  ADS  Google Scholar 

  19. Francescato, Y., Giannini, V., Yang, J., Huang, M. & Maier, S. A. Graphene sandwiches as a platform for broadband molecular spectroscopy. ACS Photonics 1, 437–443 (2014).

    Article  Google Scholar 

  20. Hu, F. et al. Imaging exciton–polariton transport in MoSe2 waveguides. Nat. Photon. 11, 356–360 (2017).

    Article  ADS  Google Scholar 

  21. Arakawa, E. T., Williams, M. W., Hamm, R. N. & Ritchie, R. H. Effect of damping on surface plasmon dispersion. Phys. Rev. Lett. 31, 1127–1129 (1973).

    Article  ADS  Google Scholar 

  22. Schuller, E., Falge, H. J. & Borstel, G. Dispersion curves of surface phonon-polaritons with backbending. Phys. Lett. A 54, 317–318 (1975).

    Article  ADS  Google Scholar 

  23. Novotny, L. Strong coupling, energy splitting, and level crossings: a classical perspective. Am. J. Phys. 78, 1199–1202 (2010).

    Article  ADS  Google Scholar 

  24. Wu, X., Gray, S. K. & Pelton, M. Quantum-dot-induced transparency in a nanoscale plasmonic resonator. Opt. Express 18, 23633–23645 (2010).

    Article  ADS  Google Scholar 

  25. Hennessy, K. et al. Quantum nature of a strongly coupled single quantum dot–cavity system. Nature 445, 896–899 (2007).

    Article  ADS  Google Scholar 

  26. Törmö, P. & Barnes, W. L. Strong coupling between surface plasmon polaritons and emitters: a review. Rep. Prog. Phys. 78, 13901 (2015).

    Article  ADS  Google Scholar 

  27. Passler, N. C. & Paarmann, A. Generalized 4 × 4 matrix formalism for light propagation in anisotropic stratified media: study of surface phonon polaritons in polar dielectric heterostructures. J. Opt. Soc. Am. B 34, 2128–2139 (2017).

    Article  ADS  Google Scholar 

  28. Pockrand, I., Brillante, A. & Möbius, D. Exciton-surface plasmon coupling: an experimental investigation. J. Chem. Phys. 77, 6289–6295 (1982).

    Article  ADS  Google Scholar 

  29. Bellessa, J., Bonnand, C., Plenet, J. C. & Mugnier, J. Strong coupling between surface plasmons and excitons in an organic semiconductor. Phys. Rev. Lett. 93, 036404 (2004).

    Article  ADS  Google Scholar 

  30. Memmi, H., Benson, O., Sadofev, S. & Kalusniak, S. Strong coupling between surface plasmon polaritons and molecular vibrations. Phys. Rev. Lett. 118, 126802 (2017).

    Article  ADS  Google Scholar 

  31. Shlesinger, I. et al. Strong coupling of nanoplatelets and surface plasmons on a gold surface. ACS Photonics 6, 2643–2648 (2019).

    Article  Google Scholar 

  32. Rozenman, G. G., Akulov, K., Golombek, A. & Schwartz, T. Long-range transport of organic exciton-polaritons revealed by ultrafast microscopy. ACS Photonics 5, 105–110 (2018).

    Article  Google Scholar 

  33. Taboada-Gutiérrez, J. et al. Broad spectral tuning of ultra-low-loss polaritons in a van der Waals crystal by intercalation. Nat. Mater. 19, 964–968 (2020).

    Article  ADS  Google Scholar 

  34. Bezares, F. J. et al. Intrinsic plasmon-phonon interactions in highly doped graphene: a near-field imaging study. Nano Lett. 17, 5908–5913 (2017).

    Article  ADS  Google Scholar 

  35. Dai, S. et al. Phonon polaritons in monolayers of hexagonal boron nitride. Adv. Mater. 31, 1806603 (2019).

    Article  Google Scholar 

  36. Caldwell, J. D. et al. Sub-diffractional volume-confined polaritons in the natural hyperbolic material hexagonal boron nitride. Nat. Commun. 5, 5221 (2014).

    Article  ADS  Google Scholar 

  37. Alfaro-Mozaz, F. J. et al. Deeply subwavelength phonon-polaritonic crystal made of a van der Waals material. Nat. Commun. 10, 42 (2019).

    Article  ADS  Google Scholar 

  38. Liu, S. et al. Single crystal growth of millimeter-sized monoisotopic hexagonal boron nitride. Chem. Mater. 30, 6222–6225 (2018).

    Article  Google Scholar 

Download references


We thank R. Esteban and J. Aizpurua for discussions. We acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities (national projects MAT2017-88358-C3, RTI2018-094830-B-100, RTI2018-094861-B-100, and the project MDM-2016-0618 of the Maria de Maeztu Units of Excellence Program), the Basque Government (grant numbers IT1164-19 and PIBA-2020-1-0014) and the European Union’s Horizon 2020 research and innovation programme under the Graphene Flagship (grant agreement numbers 785219 and 881603, GrapheneCore2 and GrapheneCore3). F. Calavelle acknowledges support from the European Union H2020 under the Marie Skłodowska-Curie Actions (766025-QuESTech). J.T.-G. acknowledges support through the Severo Ochoa Program from the Government of the Principality of Asturias (number PA-18-PF-BP17-126). P.A.-G. acknowledges support from the European Research Council under starting grant number 715496, 2DNANOPTICA. Further, support from the Materials Engineering and Processing program of the National Science Foundation, award number CMMI 1538127 for h-BN crystal growth is greatly appreciated.

Author information

Authors and Affiliations



R.H. and M.A. conceived the study with the help of A.B. and A.Y.N. Sample fabrication was performed by A.B. and F. Calavelle, supervised by F. Casanova and L.E.H. A.B. performed the experiments, data analysis and simulations. M.A., M.S. and J.T.-G. contributed to the near-field imaging experiments. M.A. and M.S. participated in the data analysis. P.L. contributed to simulations. S.L. and J.H.E. grew the isotopically enriched boron nitride. R.H. and A.Y.N. supervised the work. R.H., M.S. and A.B. wrote the manuscript with the input of A.Y.N., P.A.-G. and M.A. All authors contributed to scientific discussion and manuscript revisions.

Corresponding authors

Correspondence to Alexey Y. Nikitin or Rainer Hillenbrand.

Ethics declarations

Competing interests

R.H. is co-founder of Neaspec GmbH, a company producing scattering-type scanning near-field optical microscope systems, such as the one used in this study. The remaining authors declare no competing interests.

Additional information

Peer review information Nature Photonics thanks the anonymous reviewers 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.

Supplementary information

Supplementary Information

Supplementary Figs. 1–8, Discussion and Tables 1–3.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Bylinkin, A., Schnell, M., Autore, M. et al. Real-space observation of vibrational strong coupling between propagating phonon polaritons and organic molecules. Nat. Photonics 15, 197–202 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing