Frequency-dependent topological polaritons in carbon nanotube array/hBN heterostructures
- Yufeng Xie
- Kaijun Feng
- Zhichun Zhang
- Saiqun Ma
- Zhenghan Wu
- Yi Chen
- Chengjia Zhang
- Liguo Wang
- Kenji Watanabe
- Takashi Taniguchi
- Qi Liang
- Xiangdong Guo
- Qing Dai
- Zhiwen Shi
2026-03-24
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.