基于连续谱束缚态的高Q太赫兹全介质超表面

High-Q terahertz all-dielectric metasurface based on bound states in the continuum

为了研究基于连续谱束缚态(BIC)高品质因子Q谐振,提出了由双空心硅圆柱体组成太赫兹全介质超表面。采用数值模拟方法对结构的透射光谱及电磁场图进行了分析,并利用本征模分析的方法研究了超表面结构参数对BIC频率的影响,给出了该BIC超表面在太赫兹大频率范围工作的参数设计方法。结果表明,在3.0THz左右实现了一个可调高Q环偶极Fano谐振;本征模式的分析计算结果与入射电磁波模式的分析计算结果对称性不匹配,该超表面支持的是一个对称保护BIC。此研究为基于BIC的高Q超材料在超低阈值激光器件、非线性光学谐波产生及高灵敏度传感等领域的应用提供了理论参考。

In order to study the high quality factor Q based on the bound state in the continuum(BIC),a terahertz all-dielectric metasurface composed of double hollow silicon cylinders was proposed.The transmission spectrum and electromagnetic field diagrams of the structure were simulated and analyzed.The eigenmode analysis was used to study the influence of the metasurface structure parameters on the BIC frequency,and a BIC metasurface working in a large terahertz frequency range was desigined.The results show that an adjustable high-Q toroidal dipole Fano resonance is realized at around 3.0THz.The results of symmetry mismatch between the eigenmode analysis calculation and the incident electromagnetic wave mode.The analysis indicate that the metasurface supports a symmetry-protected BIC.This research provides a theoretical reference for the application of high-Q metamaterials based on BIC in the fields of ultra-low threshold laser devices,nonlinear optical harmonic generation,and high-sensitivity sensing.