Twisted Nano-Optics: Manipulating Light at the Nanoscale with Twisted Phonon Polaritonic Slabs
Twisted Nano-Optics: Manipulating Light at the Nanoscale with Twisted Phonon Polaritonic Slabs
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DOI：
10.1021/acs.nanolett.0c01673
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发表时间：
2020-07-08
期刊：
影响因子：
10.8
通讯作者：
Alonso-Gonzalez, Pablo
中科院分区：
文献类型：
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作者：
Duan, Jiahua;Capote-Robayna, Nathaniel;Alonso-Gonzalez, Pablo
近期的研究发现，当两层范德华（vdW）材料相互叠加且之间存在相对扭转角时，耦合系统的电子特性会发生显著变化。在此，我们证明了类似的概念可延伸至光学领域，特别是对于传播的声子极化激元——光与物质的混合相互作用。为此，我们制作了由两块支持各向异性声子极化激元（PhPs）的范德华晶体（α - MoO₃）扭转板组成的堆叠结构，并对由局域源激发的声子极化激元的传播进行成像。我们的图像显示，在临界角下，声子极化激元的等频曲线会发生拓扑转变，其中声子极化激元的传播沿着预定方向被强烈引导（沟道化区域），而没有几何扩展。这些结果展示了一种在纳米尺度上控制极化激元传播的新自由度（扭转角），在纳米成像、（生物）传感或热管理方面具有潜在应用价值。
Recent discoveries have shown that, when two layers of van der Waals (vdW) materials are superimposed with a relative twist angle between them, the electronic properties of the coupled system can be dramatically altered. Here, we demonstrate that a similar concept can be extended to the optics realm, particularly to propagating phonon polaritons-hybrid light-matter interactions. To do this, we fabricate stacks composed of two twisted slabs of a vdW crystal (alpha-MoO3) supporting anisotropic phonon polaritons (PhPs), and image the propagation of the latter when launched by localized sources. Our images reveal that, under a critical angle, the PhPs isofrequency curve undergoes a topological transition, in which the propagation of PhPs is strongly guided (canalization regime) along predetermined directions without geometric spreading. These results demonstrate a new degree of freedom (twist angle) for controlling the propagation of polaritons at the nanoscale with potential for nanoimaging, (bio)-sensing, or heat management.