通过过渡金属二硫化物单层中的激子实现光束路由
Beam Routing through Excitons in Transition Metal Dichalcogenide Monolayers
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中文总结 AI 辅助
本研究利用低温角分辨阴极发光光谱，发现过渡金属二硫化物单层的暗激子可产生定向发射，无需额外纳米结构即可实现纳米尺度光路由，为紧凑光子架构提供了新平台。
中文摘要 AI 辅助
纳米尺度的光路由通常依赖于纳米结构化表面来赋予发射方向性。我们利用低温角分辨阴极发光光谱，证明半导体的本征激子跃迁本身即可产生路由发射。我们探测了WSe₂、MoSe₂和MoTe₂的单层样品，并通过不同的角发射分布分辨出单层WSe₂的激子种类：亮激子、三激子和自旋禁阻暗激子。亮激子与三激子的面内跃迁偶极子主要向表面法向辐射，而暗激子的面外偶极子在正入射光激发下无法被观测到，却能在大角度处产生定向发射通道。我们还通过局部介电环境调控了中性与带电激子发射的平衡。本研究结果表明，过渡金属二硫化物（TMD）单层中的暗激子可作为紧凑光子架构中定向光发射的平台，无需额外的纳米结构化处理。
英文摘要
Routing light at the nanoscale typically relies on nanostructured surfaces to imprint directionality on the emission. Using low-temperature, angle-resolved cathodoluminescence spectroscopy, we show that the intrinsic excitonic transitions of a semiconductor can themselves produce routed emission. We probe monolayers of WSe$_2$, MoSe$_2$, and MoTe$_2$ and resolve the excitonic species of monolayer WSe$_2$ -- the bright exciton, the trion, and the spin-forbidden dark exciton -- through their distinct angular emission profiles. While the in-plane transition dipoles of the bright exciton and trion radiate predominantly toward the surface normal, the out-of-plane dipole of the dark exciton, inaccessible under normal-incidence optical excitation, produces a directional emission channel at large angles. We further tune the balance between neutral and charged exciton emission through the local dielectric environment. Our results establish dark excitons in TMD monolayers as a platform for directional light emission in compact photonic architectures without additional nanostructuring.
