Li Chentao, Lu Xin, Srivastava Ajit, Storm S David, Gelfand Rachel, Pelton Matthew, Sukharev Maxim, Harutyunyan Hayk
Department of Physics, Emory University, 400 Dowman Drive, Atlanta, Georgia 30322, United States.
Department of Physics, UMBC (University of Maryland, Baltimore County), 1000 Hilltop Circle, Baltimore, Maryland 21250, United States.
Nano Lett. 2021 Feb 24;21(4):1599-1605. doi: 10.1021/acs.nanolett.0c03757. Epub 2020 Dec 11.
Monolayer transition metal dichalcogenides, coupled to metal plasmonic nanocavities, have recently emerged as new platforms for strong light-matter interactions. These systems are expected to have nonlinear-optical properties that will enable them to be used as entangled photon sources, compact wave-mixing devices, and other elements for classical and quantum photonic technologies. Here, we report the first experimental investigation of the nonlinear properties of these strongly coupled systems, by observing second harmonic generation from a WSe monolayer strongly coupled to a single gold nanorod. The pump-frequency dependence of the second-harmonic signal displays a pronounced splitting that can be explained by a coupled-oscillator model with second-order nonlinearities. Rigorous numerical simulations utilizing a nonperturbative nonlinear hydrodynamic model of conduction electrons support this interpretation and reproduce experimental results. Our study thus lays the groundwork for understanding the nonlinear properties of strongly coupled nanoscale systems.
与金属等离子体纳米腔耦合的单层过渡金属二卤化物，最近已成为强光 - 物质相互作用的新平台。这些系统预计具有非线性光学特性，这将使它们能够用作纠缠光子源、紧凑型波混频器件以及经典和量子光子技术的其他元件。在此，我们通过观察与单个金纳米棒强耦合的WSe单层产生的二次谐波，首次对这些强耦合系统的非线性特性进行了实验研究。二次谐波信号的泵浦频率依赖性显示出明显的分裂，这可以用具有二阶非线性的耦合振荡器模型来解释。利用传导电子的非微扰非线性流体动力学模型进行的严格数值模拟支持了这一解释，并重现了实验结果。因此，我们的研究为理解强耦合纳米级系统的非线性特性奠定了基础。
