摘要
连续域束缚态(BIC)是位于系统辐射连续域内的束缚态。在太赫兹波段,BIC为超高品质因数(Q)的功能器件的研发提供了新思路。基于超晶格模式的对称性保护原理,设计并数值研究了由经典金属裂环谐振器(SRR)组成的太赫兹BIC超表面。在BIC向远场泄漏的过程中,通过改变SRR的间隙宽度,系统形成了可观测的准BIC(QBIC)模式。通过采用Drude模型,研究了金属材料的欧姆损耗对QBIC模式Q值的影响。提出的BIC和QBIC模式对入射角度也具有独特的响应特征。所提出的SRR基BIC超表面不仅为开发高Q太赫兹功能器件提供了一个机制清晰且易于实现的框架,而且从损耗和角度依赖特性等方面为后续太赫兹波段BIC超表面的研究提供了思路。
Objective Bound states in the continuum(BIC) refers to the non-radiative state located in the radiative continuum.BIC provides a novel method for the research and development of functional devices with ultra-high quality factor(Q) in the terahertz band.It has the potential to be used in several applications,including narrow linewidth filtering,terahertz slow light devices,and the enhanced interaction between terahertz waves and matter.In this study,terahertz BIC metasurfaces composed of classical metallic split ring resonators(SRRs) are proposed and numerically studied based on the symmetry protection principle of the structure.The leakage of BIC to the far field can be observed in the spectrum by changing the gap width of SRR to form an observable quasi BIC(QBIC) mode.Moreover,the influence of ohmic loss on the Q of QBIC is systematically studied by applying the Drude model.The proposed BIC and QBIC also have unique responses to the incident angle.The BIC based on SRR metasurface proposed in this study not only provides a new framework with clear mechanism and easy implementation for the development of high-Q terahertz functional devices,but also provides research ideas for subsequent studies on the terahertz BIC metasurface from the aspects of loss and tilted incidence.Methods The metasurfaces are composed of different superlattices based on classical metallic SRRs.A single unit cell is composed of either 2 or 4 SRRs.For the superlattices with two SRRs in the lattice,two adjacent SRRs with different orientations are arranged vertically[superlattice(1) in Fig.1(b)]or horizontally[superlattice(2) in Fig.1(c)]to form two types of superlattices.For the superlattices composed of four lattices,each SRR orients in a clockwise direction(superlattice(3) in Fig.4).All metasurfaces have 2-μm-thick high resistivity silicon wafer as substrate.The refractive index of silicon is set as 3.4 and the SRR is set as perfect electric conductor(PEC).The structure is simulated in CST microwave Studio.First,the BICs in superlattices(
作者
张星源
谷建强
师文桥
Zhang Xingyuan;Gu Jianqiang;Shi Wenqiao(Key Laboratory of Optoelectronic Information Technology,Ministry of Education,School of Precision Instrument and OptoElectronics Engineering,Center for Terahertz Waves,Tianjin University,Tianjin 300072,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2023年第2期133-141,共9页
Chinese Journal of Lasers
基金
国家自然科学基金(61935015,61975243,62005193,62027820)。
关键词
材料
连续域束缚态
太赫兹技术
超表面
等离激元
materials
bound states in continuous domain
terahertz technology
meta-surface
plasmon
