近日，德国慕尼黑路德维希马克西米利安大学Luca Sortino团队研究了块体WS₂/MoS₂异质双层范德华纳米天线中界面二次谐波的增强。相关论文于2025年9月29日发表在《光：科学与应用》杂志上。

层状范德瓦尔斯（vdW）材料因其大折射率和巨大的光学各向异性而成为纳米光子学研究的一个有前途的平台。与传统的电介质和半导体不同，层间共价键的缺失使得设计光学共振纳米光子结构的自由度达到了原子尺度：从垂直异质结构的精确堆叠到控制结晶轴之间的扭曲角度。具体来说，虽然过渡金属二硫族化合物单层表现出巨大的二阶非线性响应，但它们的2H堆叠体对应物却没有二阶非线性。

在这项工作中，研究组分析了WS₂/MoS₂异质双层薄膜在纳米结构光学天线的界面上产生的二次谐波（SHG），并通过激子共振和模拟杆驱动的场增强介导了二次谐波的产生。当满足这两个条件时，与非结构化双层相比，研究组观察到高达10²的SHG信号增强，SHG转换效率达到≈10^-7。该研究结果突出了vdW材料作为设计独特的多层光学纳米结构和超材料的平台，为纳米光子学和非线性光学的先进应用铺平了道路。

附：英文原文

Title: Interface second harmonic generation enhancement in bulk WS2/MoS2 hetero-bilayer van der Waals nanoantennas

Author: Tognazzi, Andrea, Franceschini, Paolo, Biechteler, Jonas, Ba, Enrico, Cino, Alfonso Carmelo, Tittl, Andreas, De Angelis, Costantino, Sortino, Luca

Issue&Volume: 2025-09-29

Abstract: Layered van der Waals (vdW) materials have emerged as a promising platform for nanophotonics due to large refractive indexes and giant optical anisotropy. Unlike conventional dielectrics and semiconductors, the absence of covalent bonds between layers allows for novel degrees of freedom in designing optically resonant nanophotonic structures down to the atomic scale: from the precise stacking of vertical heterostructures to controlling the twist angle between crystallographic axes. Specifically, although monolayers of transition metal dichalcogenides exhibit giant second-order nonlinear responses, their bulk counterparts with 2H stacking possess zero second-order nonlinearity. In this work, we investigate second harmonic generation (SHG) arising from the interface of WS2/MoS2 hetero-bilayer thin films with an additional SHG enhancement in nanostructured optical antennas, mediated by both the excitonic resonances and the anapole-driven field enhancement. When both conditions are met, we observe up to 102 SHG signal enhancement, compared to unstructured bilayers, with SHG conversion efficiency reaching ≈ 107. Our results highlights vdW materials as a platform for designing unique multilayer optical nanostructures and metamaterial, paving the way for advanced applications in nanophotonics and nonlinear optics.

DOI: 10.1038/s41377-025-01983-y

Source: https://www.nature.com/articles/s41377-025-01983-y