近日，美国纽约城市大学Alu, Andrea团队报道了等离子体异质结构中自旋禁止暗激子的现场增强和控制。2025年11月12日出版的《自然—光子学》杂志发表了这项成果。
原子薄范德华材料中的暗激子为信息传输和纳米光子应用提供了一个令人兴奋的平台。虽然暗激子很难通过自由空间辐射获得，但结合等离子体纳米腔的杂化异质结构提供了一个强大的平台来调整它们与光子的相互作用。
研究组设计了一个异质结构，由优化的等离子体纳米立方体耦合到包裹在薄六方氮化硼层之间的WSe2单层，以揭示一个新的暗激子家族。这些暗激子的辐射强度是亮激子的2700倍，产生了惊人的3 × 105的增强因子。研究组通过研究它们的磁光响应来证明这些暗态的自旋禁止性质。
此外，研究组还通过电掺杂控制费米能级来选择性地激活它们。这些暗激子的突出特点是线宽窄，寿命长，电和磁调制效率高。该发现开启了探索二维材料中的激子物理的潜力，应用光子异质结构在耦合过程中可保持二维材料的固有光学特性。演示的现场控制和与无源光子元件的轻松集成使该平台在纳米光子和传感应用中获得学界关注。
附：英文原文
Title: On-site enhancement and control of spin-forbidden dark excitons in a plasmonic heterostructure
Author: Quan, Jiamin, Cotrufo, Michele, Chand, Saroj, Jiang, Xuefeng, Liu, Zhida, Mejia, Enrique, Wang, Wei, Taniguchi, Takashi, Watanabe, Kenji, Grosso, Gabriele, Li, Xiaoqin, Al, Andrea
Issue&Volume: 2025-11-12
Abstract: Dark excitons in atomically thin van der Waals materials provide an exciting platform for information transport and nanophotonic applications. Although dark excitons are difficult to access through free-space radiation, hybrid heterostructures incorporating plasmonic nanocavities provide a powerful platform to tailor their interactions with photons. Here we design a heterostructure consisting of optimized plasmonic nanocubes coupled to a WSe2 monolayer encapsulated between thin hexagonal boron nitride layers to unveil a new family of dark excitons. The emission from these dark excitons is 2,700 times stronger than bright excitons, yielding a striking enhancement factor of 3×105. We demonstrate the spin-forbidden nature of these dark states by studying their magneto-optical response. Furthermore, we selectively activate them by controlling the Fermi level via electric doping. Prominent features of these dark excitons include narrow linewidths, long lifetime, efficient electrical and magnetic modulation. Our findings unlock the potential for exploring exciton physics in two-dimensional materials using photonic heterostructures that preserve the intrinsic optical properties of two-dimensional materials in the coupling process. The demonstrated on-site control and ease of integration with passive photonic components make this platform particularly compelling for nanophotonic and sensing applications.
DOI: 10.1038/s41566-025-01788-w
Source: https://www.nature.com/articles/s41566-025-01788-w