Fu Maixia, Liu Zhonghao, Liu Xueying, Niu Yingying, Zhang Yan
Opt Express. 2025 Apr 21;33(8):17492-17509. doi: 10.1364/OE.558942.
The coupling effect between incident electromagnetic waves and a properly designed metasurface can excite surface plasmon resonance at the operating frequency, which can be used to achieve significant field enhancement. The bound state in the continuum (BICs), as a unique non-radiative eigenstate, is considered to have rich physical properties. In this work, what we believe to be a new approach to enhance high-order mode electromagnetic response by utilizing near-field coupling and quasi-BIC interaction has been proposed. Quasi-BICs can be excited to achieve significant optimization of high-order coupled resonant states by breaking the symmetry of one side of the dual-port resonant ring. The electric field enhancement factor (EFEF) has been boosted by about 4.09 times, the magnetic field enhancement factor (MFEF) has been boosted by about 5.19 times, and the quality factor has been boosted to 1050, an increase of 493.22%. At the same time, the increasing resonance strength of the mode coupling term ensures sufficient radiation energy for exciting electromagnetic response. The results show that the EFEF is increased by a factor of 205.3, the MFEF is increased by a factor of 110.4, and the modulation depth is from 0 to 99.89%. In addition, by embedding actively controllable materials in the metasurface. The dimension of dynamic tuning is increased, enabling ultrafast switching of high-order modes after photon coupling and quasi-BIC coupling, and the tunable range of the eigenstate can be successfully tuned from 0 to 98.9% at the highest level. Therefore, this research has great potential applications in terahertz devices that require precise control of frequency and signal strength.
入射电磁波与精心设计的超表面之间的耦合效应可在工作频率处激发表面等离子体共振，这可用于实现显著的场增强。连续统中的束缚态（BICs）作为一种独特的非辐射本征态，被认为具有丰富的物理性质。在这项工作中，我们提出了一种利用近场耦合和准BIC相互作用来增强高阶模式电磁响应的新方法。通过打破双端口谐振环一侧的对称性，可以激发准BICs以实现高阶耦合谐振态的显著优化。电场增强因子（EFEF）提高了约4.09倍，磁场增强因子（MFEF）提高了约5.19倍，品质因数提高到1050，增加了493.22%。同时，模式耦合项共振强度的增加确保了激发电磁响应所需的足够辐射能量。结果表明，EFEF提高了205.3倍，MFEF提高了110.4倍，调制深度从0提高到99.89%。此外，通过在超表面中嵌入主动可控材料，增加了动态调谐的维度，使得在光子耦合和准BIC耦合后能够实现高阶模式的超快切换，本征态的可调范围最高可成功地从0调谐到98.9%。因此，这项研究在需要精确控制频率和信号强度的太赫兹器件中具有巨大的潜在应用价值。
