基于双准偶然连续体束缚态模式的传感与慢光研究

Investigation of Sensing and Slow-Light Based on Dual Accidental Quasi-Bound States in the Continuum

近年来,光学超表面中的连续体束缚态(BIC)因其独特的性质而受到了广泛的关注。为了研究两个准偶然连续体束缚态(A-QBIC)模式之间相互作用诱导的新颖光学现象,提出一种方形纳米孔阵列全介质超表面。结果表明,在x偏振光和y偏振光入射时能实现A-BIC现象,尤其在45°偏振光入射下可实现两个A-QBIC模式间的相互作用。利用能带理论和多极展开理论对A-QBIC模式进行分析,发现这两种模式均由环形偶极模式主导。重要的是,基于A-QBIC模式的高Q值特性,能够构建高灵敏度折射率传感,同时利用两个A-QBIC模式间具有灵活调谐度的相互作用特性,还能够实现类电磁诱导透明和可调的慢光。研究结果可为基于A-QBIC的高Q超构器件在高灵敏度折射率传感及慢光等领域的应用提供理论参考。

In recent years,bound states in the continuum(BIC)in optical metasurfaces have garnered significant attention owing to their unique properties.Because of the interaction of two accidental quasibound states in the continuum(AQBIC)modes,we explore the related novel optical phenomena in an alldielectric metasurface that comprises a square nanoaperture array.It is shown that the ABIC phenomenon can occur under x-and ypolarized normal incidences but exhibits the interaction of the two AQBIC modes under 45°polarized incidence.The AQBIC modes,which are analyzed using band and multipole expansion theories,are primarily governed by the toroidal dipole.Notably,the high Qfactor of the AQBIC modes not only allows for the implementation of highly sensitive refractive index sensing but also facilitates the realization of flexible tunability of the interaction between the two AQBIC modes,thereby achieving an analogue of electromagnetically induced transparency and tunable slowlight.Our results provide a feasible strategy to develop a high Qfactor metadevice based on AQBIC in highly sensitive refractive index sensing and slowlight applications.