To enhance and actively control terahertz (THz) anisotropy and chirality, we have designed and fabricated a THz composite device with a liquid crystal (LC) layer and Si anisotropic metasurface. By initial anchoring and electrically rotating the spatial orientation of the LC optical axis, the different symmetry relationships are obtained in this hybrid device. When the optical axis of LC is parallel or perpendicular to the optical axis of the Si metasurface, the anisotropy of the device will be enhanced or offset, which leads to a tunable phase-shift range of more than 180°. When there is an angle between the two optical axes, due to the destruction of the mirror symmetry in the LC-Si anisotropic medium, the highest circular dichroism of the device reaches 30 dB in the middle orientation state of the LC optical axis, and the active modulation can be realized by changing the bias electric field on the LC layer. This composite device demonstrates rich characteristics for the feasible manipulation of THz polarization conversion and chiral transmission, which can be applied in THz polarization imaging and chiral spectroscopy.

中文翻译：

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液晶各向异性介电超表面中的动态太赫兹各向异性和手性增强

为了增强和主动控制太赫兹 (THz) 各向异性和手性，我们设计并制造了具有液晶 (LC) 层和 Si 各向异性超表面的太赫兹复合器件。通过初始锚定和电旋转 LC 光轴的空间方向，在该混合器件中获得了不同的对称关系。当 LC 的光轴平行或垂直于 Si 超表面的光轴时，器件的各向异性会增强或抵消，从而导致可调谐的相移范围超过 180°。当两个光轴之间存在夹角时，由于LC-Si各向异性介质中镜面对称性的破坏，器件在LC光轴中间取向状态下的圆二色性最高达到30dB，并且可以通过改变LC层上的偏置电场来实现有源调制。该复合器件展示了对太赫兹偏振转换和手性透射的可行操控的丰富特性，可应用于太赫兹偏振成像和手性光谱。