- Zhang, Yiran;
- Hu, Cheng;
- Lyu, Bosai;
- Li, Hongyuan;
- Ying, Zhe;
- Wang, Lele;
- Deng, Aolin;
- Luo, Xingdong;
- Gao, Qiang;
- Chen, Jiajun;
- Du, Jing;
- Shen, Peiyue;
- Watanabe, Kenji;
- Taniguchi, Takashi;
- Kang, Ji-Hun;
- Wang, Feng;
- Zhang, Yueheng;
- Shi, Zhiwen
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.