设计了包含双层空竹的超表面,通过调节其晶格周期实现了不同阶晶格模式与超表面本征模式间的耦合,获得了 3 个强耦合区,并在两个晶格周期处实现了弗里德里希-温特根型连续域束缚态(Friedrich-Wintgen bound states in the continuum,FW-BIC).基于耦合模理论对其进行分析,理论分析结果与模拟结果吻合,进一步证明了结构的有效性.讨论了在介质间隔层中基于强耦合和FW-BIC的局域磁场增强,发现最大磁场强度是入射太赫兹波磁场强度的41209 倍,且该值是单纯的由超表面电磁共振产生的磁场强度的 4 倍.这项研究将为强场太赫兹产生和太赫兹非线性研究提供参考.
Research of BIC-based localized terahertz magnetic enhancement in double-layered diabolo metasurface
A metasurface composed of stacked double-diabolo structure was designed.By adjusting lattice period of the metasurface,hybridization between different order lattice modes and eigenmodes of the metasurface led to three strong coupling regions and two Friedrich-Wintgen BIC(FW-BIC)at two lattice periods.The analysis results based on the coupled mode theory agreed well with the numerical simulation,which further proved the validity of our structure.The strong coupling and BIC effect could be used to enhance localized magnetic field in spacer layer.The maximum magnetic field intensity was 41209 times of the incident THz wave,and this value was 4 times comparing with the purely electromagnetic resonance of metasurface.The results provide suggestions for the study of strong field THz generation and THz nonlinear optics.
metasurfacestrong couplingbound states in the continuumcoupled mode theorymagnetic field enhancement
NETL
NSTL
万方数据
