石墨烯等离激元时间晶体中的慢光

Slow light in graphene plasmonic time crystals

为了实现对慢光群速度的控制,构建了石墨烯等离激元时间晶体慢光波导。对波导采用石墨烯等离激元时间晶体来构造用于传输的Zigzag拓扑界面通道,当结构一定时动态调节石墨烯纳米盘的外加偏置电压,即可获得若干不同时刻的色散曲线,并对相应的群速度进行研究。首先,通过对蜂窝状排列的石墨烯纳米盘的不同区域施加随时间周期性变化的偏置电压,来获得石墨烯等离激元时间晶体。当晶体时间平移对称性遭到破坏时,晶体带隙会随着时间周期性出现及消失,进而呈现出能带拓扑效应。接着,构造Zigzag拓扑界面分析不同时刻下存在的拓扑界面态及其慢光模式。然后,根据该色散曲线计算出对应的群速度。最后,通过数值仿真建立慢光波导模型,并在波导光能捕获点检测场增强过程。模拟结果表明:基于石墨烯等离激元时间晶体所设计的波导可以实现很好的慢光传输效果,在波导结构固定时可以动态调节光的群速度。慢光传输下光能捕获点实现了场增强效应。该慢光波导结构简单,可动态调谐,在慢光调制器件和光储存器件中具有广阔的应用前景。

In order to control the group velocity of slow light,a graphene plasmon time crystal slow light waveguide was constructed and used for the waveguide to construct the Zigzag topology interface channel for transmission.When the structure is fixed,the external bias voltage of the graphene nano-disk can be dynamically adjusted to obtain the dispersion curves at different times.The corresponding group velocity is studied.First,the graphene plasmon time crystal is obtained by applying the bias voltages periodically varying with time to different regions of the honeycomb arranged graphene nano-disks.When the time translation symmetry of the crystal is destroyed,the crystal band gap will periodically appear and disappear with time,and exhibit the band topology effect.The Zigzag topology interface is constructed to analyze the topological interface state and its slow light mode existing at different moments.Then the corresponding group velocity is calculated according to the dispersion curve.Finally,a slow light waveguide model is established through numerical simulation,and the field enhancement process is detected at the light energy capture point of the waveguide.Simulation results show that the waveguide designed based on the graphene plasmon time crystal can achieve a good slow light transmission effect,and the group velocity of the light can be dynamically adjusted when the waveguide structure is fixed.Under slow light transmission,the light energy capture point realizes the field enhancement effect.The slow light waveguide with simple structure can be dynamically tuned,and has broad application prospects in slow light modulation devices and optical storage devices.