Abstract
Plasmons in carbon nanotubes (CNTs) have attracted significant attention due to their strong spatial confinement and high-quality factors. However, constrained by CNTs’ intrinsic electronic characteristics, modulation of their plasmon dispersion relations remains a significant challenge. Here, we report frequency-dependent topological polaritons arising from the coupling between hyperbolic plasmons and phonon polaritons in CNT-array/hexagonal boron nitride (hBN) heterostructures. In particular, we achieved a controllable topological transition of the polariton wavefront from hyperbolic to elliptical. Moreover, we demonstrated a whispering-gallery polaritonic mode confined in closed-loop CNT array on hBN. Our findings provide fundamental insights into optical topological transitions in low-dimensional heterostructures, and a promising route to manipulate light propagation and energy transfer at the nanoscale.
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Relevant data supporting the key findings of this study are available within the article and the Supplementary Information file. All raw data generated during the current study are available from the corresponding authors upon request.
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Acknowledgements
This work is supported by the National Key R&D Program of China (Nos. 2021YFA1202902 and 2022YFA1402702), the National Natural Science Foundation of China (Nos. T2525032, 12374292, 52472155, and 52522208), and Fundamental and Interdisciplinary Disciplines Breakthrough Plan of the Ministry of Education of China (JYB2025XDXM411). K.W. and T.T. acknowledge support from the JSPS KAKENHI (Grants 20H00354 and 23H02052) and the World Premier International Research Center Initiative (WPI), MEXT, Japan.
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Z.S. and Y.X. conceived the project. Z.S., X.G., and Q.D. supervised the project. Y.X. and Z.Z. grew the CNT array samples. Y.X. performed the s-SNOM measurements and carried out numerical simulations. K.F. and X.G. developed the theoretical model covering the dispersion relations and the iso-frequency contours. K.W. and T.T. grew the hBN crystals. Y.X., K.F., Z.Z., S.M., Z.W., Y.C., C.Z., L.W., Q.L., X.G., Q.D., and Z.S. discussed the data. Y.X., X.G., and Z.S. wrote the manuscript with input from all authors.
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Xie, Y., Feng, K., Zhang, Z. et al. Frequency-dependent topological polaritons in carbon nanotube array/hBN heterostructures. Nat Commun (2026). https://doi.org/10.1038/s41467-026-71100-z
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DOI: https://doi.org/10.1038/s41467-026-71100-z
