Hu Hai, Yu Renwen, Teng Hanchao, Hu Debo, Chen Na, Qu Yunpeng, Yang Xiaoxia, Chen Xinzhong, McLeod A S, Alonso-González Pablo, Guo Xiangdong, Li Chi, Yao Ziheng, Li Zhenjun, Chen Jianing, Sun Zhipei, Liu Mengkun, García de Abajo F Javier, Dai Qing
CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, 100190, Beijing, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 100049, Beijing, China.
Nat Commun. 2022 Mar 18;13(1):1465. doi: 10.1038/s41467-022-28786-8.
Due to the two-dimensional character of graphene, the plasmons sustained by this material have been invariably studied in supported samples so far. The substrate provides stability for graphene but often causes undesired interactions (such as dielectric losses, phonon hybridization, and impurity scattering) that compromise the quality and limit the intrinsic flexibility of graphene plasmons. Here, we demonstrate the visualization of plasmons in suspended graphene at room temperature, exhibiting high-quality factor Q~33 and long propagation length > 3 μm. We introduce the graphene suspension height as an effective plasmonic tuning knob that enables in situ change of the dielectric environment and substantially modulates the plasmon wavelength, propagation length, and group velocity. Such active control of micrometer plasmon propagation facilitates near-unity-order modulation of nanoscale energy flow that serves as a plasmonic switch with an on-off ratio above 14. The suspended graphene plasmons possess long propagation length, high tunability, and controllable energy transmission simultaneously, opening up broad horizons for application in nano-photonic devices.
由于石墨烯的二维特性，迄今为止，这种材料所支持的等离激元一直是在支撑样品中进行研究的。衬底为石墨烯提供了稳定性，但常常会引起不期望的相互作用（如介电损耗、声子杂化和杂质散射），这些相互作用会损害石墨烯等离激元的质量并限制其固有灵活性。在这里，我们展示了室温下悬浮石墨烯中等离激元的可视化，其品质因数Q约为33，传播长度大于3μm。我们将石墨烯悬浮高度作为一种有效的等离激元调谐旋钮，它能够原位改变介电环境，并显著调制等离激元波长、传播长度和群速度。这种对微米级等离激元传播的主动控制有助于实现近单位阶的纳米级能量流调制，从而作为一种开/关比高于14的等离激元开关。悬浮的石墨烯等离激元同时具有长传播长度、高可调性和可控的能量传输，为纳米光子器件的应用开辟了广阔前景。
