Li Hongju, Chen Bing, Qin Meng, Wang Lingling
Opt Express. 2020 Jan 6;28(1):205-215. doi: 10.1364/OE.383519.
The room-temperature strong plasmon-exciton coupling is first investigated in a metal-insulator-metal (MIM) waveguide-resonator system with WS monolayer. Finite-difference time-domain (FDTD) simulated results exhibit that the Fabry-Pérot (F-P) cavity is realized by the MIM plasmonic waveguide with two separated metal bars. When the F-P resonance is tuned to overlap with the A-exciton absorption peak of WS monolayer, the strong plasmon-exciton coupling is obtained at visible wavelengths. As a result, the spectral splitting response confirmed by the coupled-mode theory (CMT) appears in the transmission spectrum. Intriguingly, the switching response is handily witnessed by tuning the orientation of WS monolayer along the cavity, and the coupling strength is dynamically tuned by changing the position of the WS monolayer. Simultaneously, the anticrossing behavior with the Rabi splitting up to 109 meV is achieved by small changes in the length of the F-P cavity and the refractive index of dielectric in the cavity, respectively. The underlying physics is further revealed by the coupled oscillator model (COM). The proposed strong plasmon-exciton coupling can find utility in highly integrated plasmonic circuits for optical switching.
首次在具有WS单层的金属-绝缘体-金属（MIM）波导-谐振器系统中研究了室温下的强等离子体激子耦合。时域有限差分（FDTD）模拟结果表明，具有两个分离金属条的MIM等离子体波导实现了法布里-珀罗（F-P）腔。当F-P共振被调谐到与WS单层的A激子吸收峰重叠时，在可见波长处获得了强等离子体激子耦合。结果，耦合模理论（CMT）证实的光谱分裂响应出现在透射光谱中。有趣的是，通过沿腔调整WS单层的取向很容易观察到开关响应，并且通过改变WS单层的位置动态地调整耦合强度。同时，分别通过F-P腔长度和腔内电介质折射率的微小变化实现了拉比分裂高达109 meV的反交叉行为。耦合振荡器模型（COM）进一步揭示了其潜在物理机制。所提出的强等离子体激子耦合可用于高度集成的用于光开关的等离子体电路。
