You Jian Wei, Lan Zhihao, Panoiu Nicolae C
Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
Sci Adv. 2020 Mar 27;6(13):eaaz3910. doi: 10.1126/sciadv.aaz3910. eCollection 2020 Mar.
We study topologically protected four-wave mixing (FWM) interactions in a plasmonic metasurface consisting of a periodic array of nanoholes in a graphene sheet, which exhibits a wide topological bandgap at terahertz frequencies upon the breaking of time reversal symmetry by a static magnetic field. We demonstrate that due to the significant nonlinearity enhancement and large life time of graphene plasmons in specific configurations, a net gain of FWM interaction of plasmonic edge states located in the topological bandgap can be achieved with a pump power of less than 10 nW. In particular, we find that the effective nonlinear edge-waveguide coefficient is about γ ≃ 1.1 × 10 W m, i.e., more than 10 orders of magnitude larger than that of commonly used, highly nonlinear silicon photonic nanowires. These findings could pave a new way for developing ultralow-power-consumption, highly integrated, and robust active photonic systems at deep-subwavelength scale for applications in quantum communications and information processing.
我们研究了一种等离子体超表面中的拓扑保护四波混频（FWM）相互作用，该超表面由石墨烯片中的纳米孔周期性阵列组成，在静磁场打破时间反演对称性时，它在太赫兹频率下呈现出较宽的拓扑带隙。我们证明，由于石墨烯等离激元在特定配置下显著的非线性增强和较长的寿命，在拓扑带隙中位于等离子体边缘态的FWM相互作用，在泵浦功率小于10 nW时就能实现净增益。特别是，我们发现有效非线性边缘波导系数约为γ≃1.1×10 W/m，即比常用的高非线性硅光子纳米线大10多个数量级。这些发现可能为在深亚波长尺度上开发超低功耗、高度集成且稳健的有源光子系统开辟一条新途径，用于量子通信和信息处理应用。
