Department of Physics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02215, United States.
National Institute for Materials Science , Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
Nano Lett. 2017 Sep 13;17(9):5285-5290. doi: 10.1021/acs.nanolett.7b01587. Epub 2017 Aug 17.
We investigated phonon-polaritons in hexagonal boron nitride-a naturally hyperbolic van der Waals material-by means of the scattering-type scanning near-field optical microscopy. Real-space nanoimages we have obtained detail how the polaritons are launched when the light incident on a thin hexagonal boron nitride slab is scattered by various intrinsic and extrinsic inhomogeneities, including sample edges, metallic nanodisks deposited on its top surface, random defects, and surface impurities. The scanned tip of the near-field microscope is itself a polariton launcher whose efficiency proves to be superior to all the other types of polariton launchers we studied. Our work may inform future development of polaritonic nanodevices as well as fundamental studies of collective modes in van der Waals materials.
我们通过散射型扫描近场光学显微镜研究了六方氮化硼中的声子极化激元——这是一种天然的双曲范德瓦尔斯材料。我们获得的实空间纳米像详细展示了光在入射到薄的六方氮化硼片上时，当光被各种本征和非本征的不均匀性（包括样品边缘、沉积在其表面的金属纳米盘、随机缺陷和表面杂质）散射时，极化激元是如何被激发的。近场显微镜的扫描探针本身就是一个极化激元发射器，其效率证明优于我们研究的所有其他类型的极化激元发射器。我们的工作可以为未来的极化激元纳米器件的发展以及范德瓦尔斯材料中的集体模式的基础研究提供信息。
