Multifunctional metasurfaces are attracting growing attentions due to the compactness and the flexibility in beam manipulation. A bi-functional metagrating capable of anomalous refraction and beam splitting via asymmetric diffraction is designed, 3D-printed and experimentally verified at 0.14 THz. The asymmetric diffraction behavior is well explained by the excitation-direction-dependent mode amplitude inside the metagrating based on a simplified modal method. The measured efficiency of anomalous refraction towards +70° is 80.7% under $+ z$ illumination, and the measured efficiency of beam splitting is 43.7%/39.5% towards −70°/+70° under $- z$ illumination. The method here is further extended to achieve asymmetric diffraction into arbitrarily defined directions. Our work opens a new avenue in developing multifunctional and compact terahertz devices for wavefront shaping via excitation directions.

中文翻译：

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通过太赫兹光​​束的非对称衍射有效的双功能转移

由于光束操纵的紧凑性和灵活性，多功能超颖表面正引起越来越多的关注。设计了一种能够通过非对称衍射实现异常折射和分束的双功能转移光栅，并进行了3D打印，并在0.14 THz上进行了实验验证。通过基于简化模态方法的偏光内部激发方向相关的模态振幅可以很好地解释非对称衍射行为。在+ 70°下测得的异常折射效率为80.7％ $ + z $ 照明条件下，在-70°/ + 70°下测得的分束效率为43.7％/ 39.5％ $-z $ 照明。此处的方法进一步扩展为实现向任意定义方向的不对称衍射。我们的工作为开发多功能和紧凑的太赫兹设备开辟了一条新途径，该设备可通过激励方向进行波前整形。