CIC nanoGUNE, 20018 Donostia-San Sebastián, Spain.
Departamento de Física, Universidad de Oviedo, 33007 Oviedo, Spain.
Nat Commun. 2017 Jun 7;8:15624. doi: 10.1038/ncomms15624.
Polaritons in layered materials-including van der Waals materials-exhibit hyperbolic dispersion and strong field confinement, which makes them highly attractive for applications including optical nanofocusing, sensing and control of spontaneous emission. Here we report a near-field study of polaritonic Fabry-Perot resonances in linear antennas made of a hyperbolic material. Specifically, we study hyperbolic phonon-polaritons in rectangular waveguide antennas made of hexagonal boron nitride (h-BN, a prototypical van der Waals crystal). Infrared nanospectroscopy and nanoimaging experiments reveal sharp resonances with large quality factors around 100, exhibiting atypical modal near-field patterns that have no analogue in conventional linear antennas. By performing a detailed mode analysis, we can assign the antenna resonances to a single waveguide mode originating from the hybridization of hyperbolic surface phonon-polaritons (Dyakonov polaritons) that propagate along the edges of the h-BN waveguide. Our work establishes the basis for the understanding and design of linear waveguides, resonators, sensors and metasurface elements based on hyperbolic materials and metamaterials.
层状材料中的极化激元——包括范德华材料——表现出双曲色散和强场限制，这使得它们在包括光纳米聚焦、自发辐射的传感和控制在内的应用中极具吸引力。在这里，我们报告了线性天线中极化激元法布里-珀罗共振的近场研究，这些线性天线由双曲材料制成。具体来说，我们研究了由六方氮化硼（h-BN，一种典型的范德华晶体）制成的矩形波导天线中的双曲声子极化激元。红外纳米光谱和纳米成像实验揭示了具有约 100 的大品质因数的尖锐共振，表现出在传统线性天线中没有类似物的非典型模态近场模式。通过进行详细的模式分析，我们可以将天线共振分配给源自沿 h-BN 波导边缘传播的双曲表面声子极化激元（Dyakonov 极化激元）的混合的单个波导模式。我们的工作为基于双曲材料和超材料的线性波导、谐振器、传感器和超表面元件的理解和设计奠定了基础。
