近日，美国耶鲁大学Fengnian Xia团队研究了二维异质结构中的双曲声子极化子电致发光。2025年3月19日出版的《自然》杂志发表了这项成果。

声子极化子是极性电介质中光子与光学声子相干耦合产生的准粒子。由于它们能够以低损耗将电场限制在深亚波长尺度，因此它们具有独特的优势，可以实现传统光子学无法实现的一系列应用，如亚衍射成像和近场能量转移。然而，通过光学方法激发声子极化子的传统方法涉及昂贵的光源和近场方案，并且由于声子极化子和自由空间光子之间的大量动量失配，通常会导致低激发效率。

研究组证明了在适当的条件下，声子极化子可以被漂移的电荷载流子完全电激发。具体来说，在六方氮化硼（hBN）/石墨烯异质结构中，通过电驱动超高迁移率石墨烯中的电荷载流子失去平衡，他们观察到hBN的双曲声子极化子（HPhPs）在中红外频率下的亮电致发光，这显示出与黑体热发射不同的温度和载流子密度依赖性。此外，HPhP电致发光光谱的载流子密度依赖性表明，HPhP-电致发光可以由石墨烯中电荷载流子的带间跃迁和带内切伦科夫辐射引起。HPhP电致发光为实现电泵浦中红外和太赫兹声子极化子光源提供了途径。

附：英文原文

Title: Hyperbolic phonon-polariton electroluminescence in 2D heterostructures

Author: Guo, Qiushi, Esin, Iliya, Li, Cheng, Chen, Chen, Han, Guanyu, Liu, Song, Edgar, James H., Zhou, Selina, Demler, Eugene, Refael, Gil, Xia, Fengnian

Issue&Volume: 2025-03-19

Abstract: Phonon polaritons are quasiparticles resulting from the coherent coupling of photons with optical phonons in polar dielectrics1. Owing to their exceptional ability to confine electric fields to deep-subwavelength scales with low loss, they are uniquely poised to enable a suite of applications beyond the reach of conventional photonics, such as subdiffraction imaging2 and near-field energy transfer3,4,5. The conventional approach to exciting phonon polaritons through optical methods, however, involves costly light sources along with near-field schemes6,7, and generally leads to low excitation efficiency owing to substantial momentum mismatch between phonon polaritons and free-space photons. Here we demonstrate that under proper conditions, phonon polaritons can be excited all-electrically by drifting charge carriers. Specifically, in hexagonal boron nitride (hBN)/graphene heterostructures, by electrically driving charge carriers in ultrahigh-mobility graphene out of equilibrium, we observe bright electroluminescence of hBN’s hyperbolic phonon polaritons (HPhPs) at mid-infrared frequencies, which shows a temperature and carrier density dependence distinct from black-body thermal emission. Moreover, the carrier density dependence of the HPhP electroluminescence spectra reveals that HPhP electroluminescence can arise from both interband transition and intraband Cherenkov radiation8 of charge carriers in graphene. The HPhP electroluminescence offers avenues for realizing electrically pumped mid-infrared and terahertz phonon-polariton light sources.

DOI: 10.1038/s41586-025-08686-9

Source: https://www.nature.com/articles/s41586-025-08686-9