发表机构
Institute of Condensed Matter Theory and Optics, Friedrich Schiller University Jena; Abbe Center of Photonics, Friedrich-Schiller-Universität Jena（耶拿弗里德里希·席勒大学凝聚态理论与光学研究所; 耶拿弗里德里希·席勒大学阿贝光子学中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究二维材料堆叠对非线性光学响应的影响，通过基于对称性的框架将二硫化钼双层结构映射到二阶极化率张量，揭示对称性破缺对张量元素的控制，为扭曲角确定提供光学途径并指导二维材料非线性光学响应工程设计。
AI 中文摘要
理解堆叠如何控制二维材料的非线性光学响应是设计具有定制功能的范德华异质结构的关键。在此，我们建立了一个基于对称性的综合框架，将二硫化钼双层在四个点群（D3h、D3d、C3v、C3）中的结构配置映射到其二阶极化率张量χ^(2)。通过与第一性原理计算对比的群论论证，我们展示了对称性破缺如何控制这些系统中各个张量元素的激活和抑制。我们表明，扭曲配置（C3群）中面内分量χ_xxx的出现会导致二次谐波产生极瓣的刚性方位旋转，在整个光谱范围内与频率无关，锁定到结构扭曲角的一半。我们的发现为扭曲角的确定建立了一条直接的、与波长无关的光学途径，并为二维材料中非线性光学响应的工程设计提供了清晰的路线图。
英文摘要
Understanding how stacking controls the nonlinear optical response of two-dimensional materials is key to designing van der Waals heterostructures with tailored functionalities. Here, we establish a comprehensive symmetry-based framework mapping the structural configuration of MoS2 bilayers across four point groups (D3h, D3d, C3v, C3) to their second-order susceptibility tensor chi^(2). Using group-theory arguments benchmarked against first-principles response-function calculations, we demonstrate how symmetry breaking controls the activation and suppression of individual tensor elements in these systems. We show that the emergence of the in-plane component chi_xxx in twisted configurations (C3 group) induces a rigid azimuthal rotation of the second-harmonic generation polar lobes, which remains frequency-independent across the entire optical spectrum, locking to half of the structural twist angle. Our findings establish a direct, wavelength-independent optical route for twist-angle determination and provide a clear roadmap for engineering nonlinear optical responses in two-dimensional materials.
