Author(s) Zhang, Y.; Hu, C.; Lyu, B.; Li, H.; Ying, Z.; Wang, L.; Deng, A.; Luo, X.; Gao, Q.; Chen, J.; Du, J.; Shen, P.; Watanabe, K.; Taniguchi, T.; Kang, J.H.; Wang, F.; Zhang, Y.; Shi, Z.
Journal Nano Lett
Date Published 2020 Mar 11

Polaritons in two-dimensional (2D) materials have shown their unique capabilities to concentrate light into deep subwavelength scales. Precise control of the excitation and propagation of 2D polaritons has remained a central challenge for future on-chip nanophotonic devices and circuits. To solve this issue, we exploit Cherenkov radiation, a classic physical phenomenon that occurs when a charged particle moves at a velocity greater than the phase velocity of light in that medium, in low-dimensional material heterostructures. Here, we report an experimental observation of Cherenkov phonon polariton wakes emitted by superluminal one-dimensional plasmon polaritons in a silver nanowire and hexagonal boron nitride heterostructure using near-field infrared nanoscopy. The observed Cherenkov radiation direction and radiation rate exhibit large tunability through varying the excitation frequency. Such tunable Cherenkov phonon polaritons provide opportunities for novel deep subwavelength-scale manipulation of light and nanoscale control of energy flow in low-dimensional material heterostructures.

DOI 10.1021/acs.nanolett.0c00419
ISSN 1530-6992
Citation Nano Lett. 2020.

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