Generation and manipulation of phonon polaritons are of paramount importance for understanding the interaction between an electromagnetic field and dielectric materials and furthering their application in mid-infrared optical communication. However, the formation of tunable one-dimensional phonon polaritons has been rarely realized in van der Waals layered structures. Here we report the discovery of curvature-induced phonon polaritons localized at the crease of folded hexagonal boron nitrides (h-BNs) with a few atomic layers using monochromated electron energy-loss spectroscopy. Compared to bulk regions, the creased-localized signals undergo an abnormal blue-shift of 1.4 meV. First-principles calculations reveal that the energy shift arises from the optical phonon hardening in the curled region. Interestingly, the curvature-induced phonon polariton can also be controllably achieved via an electron-beam etching approach. This work opens an avenue of tailoring local electromagnetic response and creating unique phonon polariton modes in van der Waals layered materials for diverse applications.

中文翻译：

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折叠氮化硼片边缘的曲率诱导一维声子极化子

声子极化激元的产生和操纵对于理解电磁场与介电材料之间的相互作用以及进一步推动它们在中红外光通信中的应用至关重要。然而，可调谐一维声子极化激元的形成很少在范德瓦尔斯层状结构中实现。在这里，我们报告了在折叠六方氮化硼 ( h-BNs) 与几个原子层使用单色电子能量损失光谱。与大块区域相比，折痕局部信号经历了 1.4 meV 的异常蓝移。第一性原理计算表明，能量偏移是由卷曲区域中的光学声子硬化引起的。有趣的是，曲率诱导的声子极化也可以通过电子束蚀刻方法可控地实现。这项工作为定制局部电磁响应和在范德瓦尔斯层状材料中创建独特的声子极化模式开辟了一条途径，用于各种应用。