Bound states in the continuum represent a captivating and significant phenomenon in the realms of photonics, materials science, and quantum mechanics. These exceptional resonant states have emerged as crucial elements in a diverse array of nanotechnology applications including chiral nanophotonics. Applying bound states in the continuum for chiral applications is a challenging problem and usually requires some additional complicated steps such as multi‐layer lithography, adding superstrate with index matching materials and geometry parameters adjusting. Nevertheless, creating a structure placed in inhomogeneous background that is capable to perfectly convert one circular polarization to the opposite one is still a challenging problem. This work presents chiral metasurface based on bound states in the continuum allowing to achieve perfect unitary circular conversion in an inhomogeneous environment. This approach is based on a coupling of two chiral but not perfect resonances which makes it possible to get one mode with chiral dichroism value of 1. A theoretical model is built, perform numerical calculation and conduct an experimental verification to prove this concept. The presented results could find many applications in sensing, optics, telecommunications, biomedical and chemical analysis.

中文翻译：

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在不均匀环境中实现完美手性二向色性的面内超表面设计


连续体中的束缚态代表了光子学、材料科学和量子力学领域中一个迷人而重要的现象。这些特殊的谐振态已成为包括手性纳米光子学在内的各种纳米技术应用中的关键元素。在连续体中应用束态以进行手性应用是一个具有挑战性的问题，通常需要一些额外的复杂步骤，例如多层光刻、使用折射率匹配材料添加 superstrate 和几何参数调整。然而，创建一个放置在非均匀背景中的结构，能够将一个圆极化完美地转换为相反的圆极化仍然是一个具有挑战性的问题。这项工作提出了基于连续体中束缚态的手性超表面，允许在不均匀环境中实现完美的幺正圆转换。这种方法基于两个手性但不完美的共振的耦合，这使得获得一个手性二色值为 1 的模式成为可能。建立理论模型，进行数值计算并进行实验验证以证明这一概念。所提出的结果可以在传感、光学、电信、生物医学和化学分析中找到许多应用。