具有可切换手性光学响应的全介质双原子超表面

Switchable chiro-optical responses in all-dielectric diatomic metasurfaces

摘要:

手性,通常表现为不能通过平移或旋转与其镜像结构重合的现象。光学领域中手性结构与圆偏振(circular polarization,CP) 光间的相互作用会产生圆二色性(circular dichroism,CD),在偏振开关、滤波和传感等领域具有重要的应用价值。提出了一种工作在近红外(near-infrared,NIR)波段的单层全介质双原子超表面的设计策略,相邻纳米硅柱之间产生的干涉效应能够诱导圆偏振光的自旋选择性透射,在292.33 THz处产生高达95.33%的CD振幅。通过改变右侧交叉椭圆硅柱的相对旋转角度可以重构超表面单元,进一步提供了一种灵活的方式来切换CD光谱的响应类型。该设计还可以作为线偏振光到圆偏振光的偏振转换器,并仍然具有可重构特性。所设计的双原子手性超表面可广泛应用于动态多功能器件,为集成光子器件的设计与发展提供了新思路。

Abstract:

Chirality,which generally manifests itself as the inability to coincide with its mirror image structure by translation or rotation.In optics,the interaction between chiral structures and circularly polarized light produces circular dichroism (CD),which has great applications in polarization switching,filtering,and sensing.Here,a design strategy is proposed for a single-layer all-dielectric diatomic metasurface working in the near-infrared (NIR) band,where the interference effect generated between neighboring nanoscale silicon pillars is capable of inducing spin-selective transmission of circularly polarized light,producing up to 95.33% of the CD amplitude at 292.33 THz.The metaface unit can be reconfigured by varying the relative rotation angle of the right cross elliptical silicon pillars,further providing a flexible way to switch the type of response for CD spectrum.The proposed design can also be employed as a polarization converter from linearly to circularly polarized light and still have reconfigurable properties.Therefore,the designed diatomic chiral metasurfaces can be generally applied to dynamic multifunctional devices,which provides a new idea for the design and development of integrated photonic devices.