Circular dichroism (CD) is widely used in enantiomer identification, photodetection, and circular polarization devices. Improving the CD signal of easily prepared 3D chiral nanostructures by designing templates remains a challenge in this field. Herein, double-layer nanostructures, which can be prepared with one-time electron beam lithography (EBL) combined with electron beam deposition, are theoretically and experimentally shown to exhibit a CD effect. Theoretical results show that the double-layer nanostructures form strong local electromagnetic fields between the layers due to near-field coupling and that the relative positions of the different parts that break the symmetry of the nanostructures lead to differences in distorted magnetic fields and transmission under circularly polarized light (CPL) excitation, thereby producing CD effects. In addition, modifications in arm positions change the asymmetry of the structure, resulting in large CD effects due to amplified left and right CPL transmission differences. Furthermore, the CD effect can be tuned remarkably by changing the VO₂ state to regulate the near-field coupling. These results provide a way to obtain CD effects by using identical nanostructures in the upper and bottom layers and manipulating near-field coupling. Such chiral devices have potential applications in chiral recognition, remote temperature readout, and advanced control of chemical reactions.

中文翻译：

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近场耦合诱导圆二色性双层手征系统

圆二色性 (CD) 广泛用于对映异构体识别、光电检测和圆偏振设备。通过设计模板来改善易于制备的 3D 手性纳米结构的 CD 信号仍然是该领域的一个挑战。在这里，可以用一次性电子束光刻 (EBL) 结合电子束沉积制备的双层纳米结构在理论上和实验上都显示出 CD 效应。理论结果表明，双层纳米结构由于近场耦合在层间形成强局部电磁场，破坏纳米结构对称性的不同部分的相对位置导致扭曲磁场和圆形下传输的差异偏振光 (CPL) 激发，从而产生 CD 效果。此外，臂位置的修改会改变结构的不对称性，由于左右 CPL 传输差异的放大，导致较大的 CD 效应。此外，通过改变 VO 可以显着调整 CD 效果₂状态来调节近场耦合。这些结果提供了一种通过在上层和底层使用相同的纳米结构并操纵近场耦合来获得 CD 效应的方法。这种手性器件在手性识别、远程温度读数和化学反应的高级控制方面具有潜在应用。