Perfect intrinsic and nonlinear chirality simultaneously driven by half-integer topological charge

作者：Shijie Cai, Jiafei Chen, Xiaoshan Liu, Guolan Fu, Guiqiang Liu, Jing Chen, Chaojun Tang, Wei Du, Zhengqi Liu · 发表于：Physical review. B./Physical review. B · 年份：2024 · DOI：10.1103/physrevb.109.165420 · 被引用次数：53 · 研究领域：Metamaterials and Metasurfaces Applications、Orbital Angular Momentum in Optics、Mechanical and Optical Resonators

Bound states in the continuum hold extraordinary optical topological properties and can significantly enhance the interaction between light and matter including the circular dichroism (CD) in chiral resonant metasurfaces. In this paper, we demonstrate the split and displacement of topological charges through tilted double-elliptical half-disk metasurfaces. It enables the feasibility to attain perfect intrinsic chiroptic responses, with a CD exceeding 0.99. The ellipticity (\ensuremath{\chi}) of the intrinsic chiroptic response, induced by vertical incidence, is also \ensuremath{\sim}1. In addition to linear chirality CD, significant near-field enhancement contrast is observed at the positions of half-integer topological charge, leading to remarkable nonlinear CD approaching a nearly perfect value of 1. The proposed metasurface simultaneously possesses perfect intrinsic chirality and nonlinear chirality, providing an avenue for the multifaceted development of planar optical devices.