Wang Ranran, Zhang Zhihong
Opt Lett. 2024 Aug 1;49(15):4082-4085. doi: 10.1364/OL.528798.
In two-dimensional (2D) hyperbolic materials, energy is directed into their deep subwavelength polaritonic modes through four narrow beams. Hyperbolic whispering-gallery mode nanocavity-confined phonon polaritons (PhPs) display a strongly enhanced light-matter interaction in the infrared regime. Particularly, the unidirectional phonon-polarization excitation in nanocavities has a potential application value in an on-chip integrated optical circuit design, efficient optical sensors, and enhanced spectral technology. Here, we explore the hyperbolic whispering-gallery mode PhPs on the cross section of a hexagonal BN nanotube (BNNT) and demonstrate that efficient unidirectional excitation can be achieved using a circularly polarized electric dipole, combining with optical spin-orbit coupling. Our results demonstrated that the undirectionality of the hyperbolic polariton propagation in a nanocavity can be conveniently achieved, independent of the structure symmetry of the nanocavity, providing potential applications in nanoscale light propagation, on-chip optical devices, and communication.
在二维（2D）双曲材料中，能量通过四条窄光束被引导到其深亚波长极化子模式中。双曲回音壁模式纳米腔限制的声子极化激元（PhP）在红外区域表现出强烈增强的光与物质相互作用。特别地，纳米腔中的单向声子极化激发在片上集成光路设计、高效光学传感器和增强光谱技术方面具有潜在的应用价值。在此，我们探索了六方氮化硼纳米管（BNNT）横截面上的双曲回音壁模式PhP，并证明使用圆偏振电偶极子结合光学自旋轨道耦合可以实现高效的单向激发。我们的结果表明，纳米腔中双曲极化激元传播的无方向性可以方便地实现，与纳米腔的结构对称性无关，这为纳米级光传播、片上光学器件和通信提供了潜在应用。
