Sang Tian, Mi Qing, Yang Chaoyu, Zhang Xianghu, Wang Yueke, Ren Yongze, Xu Ting
Department of Photoelectric Information Science and Engineering, School of Science, Jiangnan University, Wuxi 214122, China.
National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
Nanophotonics. 2024 Jan 18;13(8):1369-1377. doi: 10.1515/nanoph-2023-0673. eCollection 2024 Apr.
High-Q resonances in metasurfaces, stemming from symmetry-protected bound states in the continuum (BICs), have proven to be effective for achieving high-performance optical devices. However, the properties associated with symmetry-protected BICs are inherently limited, as even a slight variation in the asymmetry parameter leads to a noticeable shift in the resonance location. Herein, we introduce the concept of relative shift-induced quasi-BICs (QBICs) within dimerized silicon (Si) meta-lattices (DSMs), which can be excited when a nonzero relative shift occurs, a result of in-plane inversion symmetry breaking and Brillouin zone folding within the structure. These QBICs have resonance locations that remain insensitive to variations in asymmetrical parameters. Additionally, their Q-factors can be flexibly tuned, benefiting from the inverse square dependence on asymmetrical parameters. In experiment, six DSMs with different relative shifts are fabricated and the asymmetry parameter-insensitive resonant modes under two orthogonal polarization states are experimentally observed in the optical communication waveband. Our results offer unique opportunities for constructing high-Q resonators with enhanced performances, which can be applied in various optical fields.
超表面中的高品质因子共振源于连续统中的对称性保护束缚态（BIC），已被证明对实现高性能光学器件有效。然而，与对称性保护BIC相关的特性本质上是有限的，因为即使不对称参数有轻微变化也会导致共振位置出现明显偏移。在此，我们引入了二聚化硅（Si）超晶格（DSM）中相对位移诱导准BIC（QBIC）的概念，当结构内发生非零相对位移时（这是面内反演对称性破缺和布里渊区折叠的结果），这些QBIC可以被激发。这些QBIC的共振位置对不对称参数的变化不敏感。此外，受益于对不对称参数的平方反比依赖关系，它们的品质因子可以灵活调节。在实验中，制备了六种具有不同相对位移的DSM，并在光通信波段实验观测到了两种正交偏振态下对不对称参数不敏感的共振模式。我们的结果为构建具有增强性能的高品质因子谐振器提供了独特机会，可应用于各种光学领域。
