High-Q resonances governed by the quasi-bound states in the continuum in all-dielectric metasurfaces  

作　　者：Cizhe Fang Qiyu Yang Qingchen Yuan Xuetao Gan Jianlin Zhao Yao Shao Yan Liu Genquan Han Yue Hao 

机构地区：[1]State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology,Shaanxi Joint Key Laboratory of Graphene,School of Microelectronics,Xidian University,Xi’an 710071,China [2]MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions,and Shaanxi Key Laboratory of Optical Information Technology,School of Physical Science and Technology,Northwestern Polytechnical University,Xi’an 710129,China [3]Shanghai Energy Internet Research Institute of State Grid,251 Libing Road,Pudong New Area,Shanghai 201210,China

出　　处：《Opto-Electronic Advances》2021年第6期1-10,共10页光电进展（英文）

基　　金：support from the National Key Research and Development Project (Grant No. 2018YFB2200500, 2018YFB2202800);National Natural Science Foundation of China (Grant No. 61534004, 91964202, 61874081, 61851406, 91950119, and 61905196)。

摘　　要：The realization of high-Q resonances in a silicon metasurface with various broken-symmetry blocks is reported. Theoretical analysis reveals that the sharp resonances in the metasurfaces originate from symmetry-protected bound in the continuum(BIC) and the magnetic dipole dominates these peculiar states. A smaller size of the defect in the broken-symmetry block gives rise to the resonance with a larger Q factor. Importantly, this relationship can be tuned by changing the structural parameter, resulting from the modulation of the topological configuration of BICs. Consequently, a Q factor of more than 3,000 can be easily achieved by optimizing dimensions of the nanostructure. At this sharp resonance, the intensity of the third harmonic generation signal in the patterned structure can be 368 times larger than that of the flat silicon film. The proposed strategy and underlying theory can open up new avenues to realize ultrasharp resonances, which may promote the development of the potential meta-devices for nonlinearity, lasing action, and sensing.

关 键 词：all-dielectric metasurface bound states in the continuum optical nonlinearity topological configuration 

分 类 号：TB34[一般工业技术—材料科学与工程]