Hu Hai, Zhai Feng, Hu Debo, Li Zhenjun, Bai Bing, Yang Xiaoxia, Dai Qing
National Center for Nanoscience and technology, Beijing 100190, China.
Department of Physics, Zhejiang Normal University, Jinhua 321004, China.
Nanoscale. 2015 Dec 14;7(46):19493-500. doi: 10.1039/c5nr05175d.
The electrostatic tunability of graphene is vital in the field of active plasmons and would be beneficial in tunable infrared and terahertz optical element applications. The key to realizing broad tunability is achieving high carrier densities in graphene. Here we use an ion-gel, currently one of the most efficient dielectrics with ultra-high capacitance, to realize broadly tunable graphene plasmons (∼1270 cm(-1)) with low voltage modulation (∼4 V shifted from the Dirac point). We further explore the coupling between graphene plasmons and the molecular vibration modes of the ion-gel, since strong plasmon-phonon coupling can split the plasmon resonance peak into multi-peaks and reduce their tunability. Our experiments demonstrate weak plasmon-phonon coupling in the graphene/ion-gel system, which has limited effects on plasmon properties. These properties make ion-gels an effective dielectric for broadly tunable graphene plasmonic devices, such as new optical modulators, filters and wavelength multiplexers.
石墨烯的静电可调性在有源等离子体激元领域至关重要，并且在可调谐红外和太赫兹光学元件应用中会很有帮助。实现广泛可调性的关键在于在石墨烯中实现高载流子密度。在这里，我们使用离子凝胶（目前是具有超高电容的最有效电介质之一）来实现具有低电压调制（相对于狄拉克点偏移约4 V）的广泛可调石墨烯等离子体激元（约1270 cm(-1)）。我们进一步探索了石墨烯等离子体激元与离子凝胶的分子振动模式之间的耦合，因为强等离子体激元 - 声子耦合会将等离子体激元共振峰分裂为多个峰并降低其可调性。我们的实验表明，石墨烯/离子凝胶系统中存在弱等离子体激元 - 声子耦合，这对等离子体激元特性的影响有限。这些特性使离子凝胶成为用于广泛可调石墨烯等离子体激元器件（如新型光调制器、滤波器和波长复用器）的有效电介质。
