Duan, J.; Álvarez-Pérez, G.; Voronin, K. V.; Prieto Gonzalez, IvanISTA ; Taboada-Gutiérrez, J.; Volkov, V. S.; Martín-Sánchez, J.; Nikitin, A. Y.; Alonso-González, P.
Polaritons with directional in-plane propagation and ultralow losses in van der Waals (vdW) crystals promise unprecedented manipulation of light at the nanoscale. However, these polaritons present a crucial limitation: their directional propagation is intrinsically determined by the crystal structure of the host material, imposing forbidden directions of propagation. Here, we demonstrate that directional polaritons (in-plane hyperbolic phonon polaritons) in a vdW crystal (α-phase molybdenum trioxide) can be directed along forbidden directions by inducing an optical topological transition, which emerges when the slab is placed on a substrate with a given negative permittivity (4H–silicon carbide). By visualizing the transition in real space, we observe exotic polaritonic states between mutually orthogonal hyperbolic regimes, which unveil the topological origin of the transition: a gap opening in the dispersion. This work provides insights into optical topological transitions in vdW crystals, which introduce a route to direct light at the nanoscale.
G.Á.-P. and J.T.-G. acknowledge support through the Severo Ochoa Program from the government of the Principality of Asturias (grant nos. PA20-PF-BP19-053 and PA-18-PF-BP17-126, respectively). K.V.V. and V.S.V. acknowledge the Ministry of Science and Higher Education of the Russian Federation (no. 0714-2020-0002). J. M.-S. acknowledges financial support through the Ramón y Cajal Program from the government of Spain and FSE (RYC2018-026196-I). A.Y.N. acknowledges the Spanish Ministry of Science, Innovation and Universities (national project no. MAT201788358-C3-3-R), and the Basque Department of Education (PIBA-2020-1-0014). P.A.-G. acknowledges support from the European Research Council under starting grant no. 715496, 2DNANOPTICA.
Duan J, Álvarez-Pérez G, Voronin KV, et al. Enabling propagation of anisotropic polaritons along forbidden directions via a topological transition. Science Advances. 2021;7(14). doi:10.1126/sciadv.abf2690
Duan, J., Álvarez-Pérez, G., Voronin, K. V., Prieto Gonzalez, I., Taboada-Gutiérrez, J., Volkov, V. S., … Alonso-González, P. (2021). Enabling propagation of anisotropic polaritons along forbidden directions via a topological transition. Science Advances. AAAS. https://doi.org/10.1126/sciadv.abf2690
Duan, J., G. Álvarez-Pérez, K. V. Voronin, Ivan Prieto Gonzalez, J. Taboada-Gutiérrez, V. S. Volkov, J. Martín-Sánchez, A. Y. Nikitin, and P. Alonso-González. “Enabling Propagation of Anisotropic Polaritons along Forbidden Directions via a Topological Transition.” Science Advances. AAAS, 2021. https://doi.org/10.1126/sciadv.abf2690.
J. Duan et al., “Enabling propagation of anisotropic polaritons along forbidden directions via a topological transition,” Science Advances, vol. 7, no. 14. AAAS, 2021.
Duan J, Álvarez-Pérez G, Voronin KV, Prieto Gonzalez I, Taboada-Gutiérrez J, Volkov VS, Martín-Sánchez J, Nikitin AY, Alonso-González P. 2021. Enabling propagation of anisotropic polaritons along forbidden directions via a topological transition. Science Advances. 7(14), eabf2690.
Duan, J., et al. “Enabling Propagation of Anisotropic Polaritons along Forbidden Directions via a Topological Transition.” Science Advances, vol. 7, no. 14, eabf2690, AAAS, 2021, doi:10.1126/sciadv.abf2690.
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