Huang Zhisen, Wang Jin, Jia Wei, Zhang Shanwen, Zhou Changhe
Opt Express. 2024 Sep 9;32(19):33029-33041. doi: 10.1364/OE.533165.
Chiral metasurfaces with strong chirality and high quality factors (Q-factors) have become essential components for achieving strong light-matter interactions and have a wide range of applications in chiral lasers, detectors, etc. However, current schemes primarily focus on enhancing the chiral response and Q-factor, with limited consideration of their modulability and flexibility. In this paper, we present a chiral a-Si metasurface that can support multiple symmetry-protected bound states in the continuum (BIC). The perfect extrinsic and intrinsic chiral responses (circular dichroism exceeding 0.99), with ultra-high Q-factors, are achieved by utilizing quasi-BICs induced by illumination symmetry and in-plane symmetry breaking. The circular dichroism value and the transmittance of the two circular polarization states can be arbitrarily controlled by adjusting the structural parameters. Furthermore, the feasibility of achieving dynamic modulation of chiral response is demonstrated based on the a-Si-graphene hybrid metasurface. Our research offers an approach to the design of controllable planar optical chirality, which also provides promising avenues for applications in spin-selective bio-detection, electrically tunable chiral switching, and chiral lasers.
具有强手性和高品质因数（Q 因子）的手性超表面已成为实现强光与物质相互作用的关键组件，并在手性激光器、探测器等领域有广泛应用。然而，目前的方案主要集中在增强手性响应和 Q 因子，对其可调制性和灵活性的考虑有限。在本文中，我们提出了一种手性非晶硅超表面，它可以支持多个连续统中的对称保护束缚态（BIC）。通过利用由照明对称性和面内对称性破缺诱导的准 BIC，实现了完美的外在和内在手性响应（圆二色性超过 0.99）以及超高的 Q 因子。通过调整结构参数，可以任意控制圆二色性值和两个圆偏振态的透射率。此外，基于非晶硅 - 石墨烯混合超表面证明了实现手性响应动态调制的可行性。我们的研究为可控平面光学手性的设计提供了一种方法，也为自旋选择性生物检测、电可调手性开关和手性激光器等应用提供了有前景的途径。
