Qi Ruishi, Wang Renfei, Li Yuehui, Sun Yuanwei, Chen Shulin, Han Bo, Li Ning, Zhang Qing, Liu Xinfeng, Yu Dapeng, Gao Peng
Division of Nanophotonics, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , China.
Shenzhen Key Laboratory of Quantum Science and Engineering , Shenzhen 518055 , China.
Nano Lett. 2019 Aug 14;19(8):5070-5076. doi: 10.1021/acs.nanolett.9b01350. Epub 2019 Jul 24.
Phonon polaritons hold potential prospects of nanophotonic applications at the mid- and far-infrared wavelengths. However, their experimental investigation in the far-infrared range has long been a technical challenge due to the lack of suitable light sources and detectors. To obviate these difficulties, here we use an electron probe with sub-10 meV energy resolution and subnanometer spatial resolution to study far-infrared surface phonon polaritons (∼50-70 meV) in ZnO nanostructures. We observe ultraslow propagation and interference fringes of propagating surface phonon polaritons and obtain their dispersion relation through measurements in the coordinate space. By mapping localized modes in nanowires and flakes, we reveal their localized nature and investigate geometry and size effects. Associated with simulation, we show that surface phonon polariton behaviors can be well described by the local continuum dielectric model. Our work paves the way for spatial-resolved investigation of surface phonon polaritons by electron probes and forwards polaritonics in the far-infrared range.
声子极化激元在中红外和远红外波长的纳米光子学应用中具有潜在的前景。然而，由于缺乏合适的光源和探测器，对其在远红外波段的实验研究长期以来一直是一项技术挑战。为了克服这些困难，我们在这里使用具有低于10毫电子伏特能量分辨率和亚纳米空间分辨率的电子探针，来研究氧化锌纳米结构中的远红外表面声子极化激元（~50-70毫电子伏特）。我们观察到传播表面声子极化激元超慢传播和干涉条纹，并通过坐标空间测量获得其色散关系。通过绘制纳米线和薄片中的局域模，我们揭示了它们的局域性质，并研究了几何形状和尺寸效应。结合模拟，我们表明表面声子极化激元行为可以通过局部连续介质电介质模型得到很好的描述。我们的工作为通过电子探针进行表面声子极化激元的空间分辨研究铺平了道路，并推动了远红外波段的极化激元学发展。
