Optical chirality, which plays important roles in liquid crystal display and biological and chemical detection, has been attracting scientists’ attention due to its potential applications in optical information processing. Usually, the chiral optical response of natural molecules is very weak. However, the emergence of metasurfaces offers a promising solution to solve this issue. By judiciously designing the geometry of meta-atoms, we have realized strong optical circular dichroism (CD) in both linear and nonlinear optical regimes. However, tuning of the CD with a metasurface remains challenging. Here, we propose the twist-angle-controlled nonlinear CD effect by using the second-harmonic generation process on a gold–crystal hybrid metasurface. The CD effect of the second-harmonic waves can be tuned well by controlling the twist angle between the two constituent materials. The proposed hybrid metasurface may open new avenues for developing ultracompact and multifunctional nonlinear optical devices.

中文翻译：

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金晶体混合超表面上扭转角控制的非线性圆二色性


光学手性在液晶显示和生物化学检测中发挥着重要作用，因其在光学信息处理中的潜在应用而引起了科学家的关注。通常，天然分子的手性光学响应非常弱。然而，超表面的出现为解决这个问题提供了一个有希望的解决方案。通过明智地设计元原子的几何形状，我们在线性和非线性光学体系中实现了强光学圆二色性（CD）。然而，用超表面调整 CD 仍然具有挑战性。在这里，我们提出了通过在金晶体混合超表面上使用二次谐波生成过程来实现扭转角控制的非线性 CD 效应。通过控制两种组成材料之间的扭转角可以很好地调节二次谐波的CD效应。所提出的混合超表面可能为开发超紧凑和多功能非线性光学器件开辟新途径。