Title: Role of Coherence in Polarization Response of Hybrid Monolayer MoS$_2$-Gold Nanoparticle Systems Show Chinese title

Title: Coherence在混合单层MoS$_2$-金纳米颗粒系统偏振响应中的作用

Abstract: Monolayers of transition metal dichacogenides show strong second-order nonlinearity and symmetry-driven selection rules from their three-fold lattice symmetry. This process resembles the valley-contrasting selection rules for photoluminescence in these materials. However, the underlying physical mechanisms fundamentally differ since second harmonic generation is a coherent process, whereas photoluminescence is incoherent, leading to distinct interactions with photonic nanoresonators. In this study, we investigate the far- field circular polarization properties of second harmonic generation from MoS$_2$ monolayers resonantly interacting with spherical gold nanoparticles. Our results indicate that the coherence of the second harmonic allows its polarization to be mostly preserved, unlike in an incoherent process, where the polarization is scrambled. These findings provide important insights for future applications in valleytronics and quantum nanooptics, where both coherent and incoherent processes can be probed in such hybrid systems without altering sample geometry or operational wavelength. Show Chinese abstract

Abstract: 过渡金属二硫属化物的单层表现出由其三重晶格对称性引起的强二阶非线性和对称性驱动的选择规则。 这一过程类似于这些材料中光致发光的谷对比选择规则。 然而，基本的物理机制存在根本差异，因为二次谐波产生是一个相干过程，而光致发光是不相干的，导致与光子纳米共振器的不同相互作用。 在本研究中，我们研究了MoS$_2$单层与球形金纳米颗粒共振相互作用时的远场圆偏振特性。 我们的结果表明，二次谐波的相干性使其偏振大部分得以保持，这与不相干过程中偏振被混淆的情况不同。 这些发现为未来在谷电子学和量子纳米光学中的应用提供了重要见解，在这些应用中，可以在不改变样品几何结构或工作波长的情况下，在这种混合系统中探测相干和不相干过程。