Niu Jiaqi, Zhai Yueqi, Han Qingqing, Liu Jingquan, Yang Bin
Opt Lett. 2021 Jan 15;46(2):162-165. doi: 10.1364/OL.410791.
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- 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.
光学系统中连续域束缚态（BICs）的实现主要依赖于对称性破缺。相比之下，另一种机制，即共振捕获（或弗里德里希 - 温特根）情形，已在有限的介质谐振内含物范围内或非中心点处被报道。在本信函中，当将金属建模为理想电导体时，我们证明了两个共面金属裂环谐振器之间的耦合系数可以被调谐，以满足法向太赫兹（THz）入射时的弗里德里希 - 温特根BIC条件。应用时间耦合模理论来验证结果。在实验上，由于本构材料的固有耗散损耗，已观察到一种BIC诱导的隐身效应。我们的发现提出了一种除传统对称性破缺方法之外在金属超表面中构建BICs的替代策略。
