The realization of bound states in the continuum (BICs) in optical systems has been relying mainly on symmetry breaking. In contrast, another mechanism, known as resonance-trapped (or Friedrich–Wintgen) scenario, has been reported in the limited scope of dielectric resonant inclusions or at off-$\Gamma$ points. In this Letter, we demonstrate that the coupling coefficient between two coplanar metallic split-ring resonators can be tuned to satisfy the Friedrich–Wintgen BIC condition with normal terahertz (THz) incidence when metals are modeled as perfect electric conductors. Temporal coupled-mode theory is applied to validate the results. Experimentally, a BIC-induced cloaking effect has been observed, owing to the intrinsic dissipation loss of the constitutive materials. Our findings suggest an alternative strategy to construct BICs in metallic metasurfaces apart from conventional symmetry-breaking methods.

中文翻译：

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太赫兹金属超表面连续区域中的共振陷阱束缚态

光学系统中连续体（BIC）中束缚态的实现主要依靠对称性破坏。相反，在介电共振夹杂物的有限范围内或偏离伽玛值时，已经报道了另一种机制，称为共振陷获（或Friedrich–Wintgen）方案。点。在这封信中，我们证明了当将金属建模为理想的电导体时，可以调整两个共面金属开口环谐振器之间的耦合系数，使其满足具有正常太赫兹（THz）入射的Friedrich-Wintgen BIC条件。应用时间耦合模式理论来验证结果。在实验中，由于本构材料的固有耗散损失，已经观察到了BIC引起的隐蔽效果。我们的发现表明，除了常规的对称破坏方法以外，还可以采用另一种策略在金属超表面上构造BIC。