金属光栅表面等离激元与二硫化钨激子的强耦合特性  

Strong Coupling Between Surface Plasmons in Metallic Grating andExcitons in Tungsten Disulfide

作　　者：苏盈文 陆华 石首浩 李頔琨 王向贤[2] 赵建林[1] Su Yingwen;Lu Hua;Shi Shouhao;Li Dikun;Wang Xiangxian;Zhao Jianlin(Key Laboratory of Light Field Manipulation and Information Acquisition,Ministry of Industry and Information Technology,School of Physical Science and Technology,Northwestern Polytechnical University,Shaanxi Key Laboratory of Optical Information Technology,Xi'an 710129,Shaanxi,China;School of Science,Lanzhou University of Technology,Lanzhou 730050,Gansu,China)

机构地区：[1]西北工业大学物理科学与技术学院光场调控与信息感知工业和信息化部重点实验室,陕西省光信息技术重点实验室,陕西西安710129 [2]兰州理工大学理学院,甘肃兰州730050

出　　处：《光学学报》2024年第4期310-318,共9页Acta Optica Sinica

基　　金：国家自然科学基金(11974283,11774290,61705186);“双一流”高校建设基金(0206022GH0202);中央高校基本科研业务费项目(D5000220175)。

摘　　要：本文研究了金属光栅表面等离激元与单层二硫化钨激子的耦合共振特性。利用时域有限差分法模拟了一维金光栅/单层二硫化钨混合结构的光谱响应及电场强度分布。结果表明,金光栅表面等离激元与单层二硫化钨激子耦合可产生光谱劈裂。当改变金光栅的结构参数时,混合结构的反射光谱出现了明显的反交叉现象。采用时域耦合模理论拟合了混合结构不同参数时的反射光谱,拟合结果与数值模拟符合较好。金光栅表面等离激元与单层二硫化钨激子的耦合作用满足强耦合判据。耦合振荡器模型分析结果表明,当金光栅周期为400 nm、宽度为300 nm时,混合结构强耦合光谱的拉比劈裂为54.6 meV,其与时域耦合模理论结果一致。该工作将为表面等离激元与激子强耦合作用的深入研究与器件开发开辟新途径。Objective In recent years,strong coupling between surface plasmons and excitons has become a research hotspot in lightmatter interactions.As an important two-dimensional material,transition metal dichalcogenides(TMDs)have caught extensive attention due to their unique optoelectrical properties.TMD monolayers are direct band gap semiconductors and their excitons have large transition dipole moments and binding energy,which is beneficial to realize the strong coupling between photons and excitons at room temperature.Surface plasmons in metallic nanostructures feature near-field enhancement and small mode volume,providing an effective platform for realizing its strong coupling with excitons.Recently,the strong coupling has been achieved between surface plasmons and TMD excitons in plasmonic systems such as metallic nanoarray,nanoparticles,and nanocavities.One-dimensional(1D)metallic grating is a typical plasmonic structure,in which the coupling effect between surface plasmons and TMD excitons has been rarely studied till now.Thus,we investigate the plasmon-exciton strong coupling behavior in the 1D metallic grating integrated with monolayer tungsten disulfide(WS_(2)).Method We build a simulation model by adopting the finite-difference time-domain(FDTD)method and numerically investigate the coupling effect between surface plasmons in the gold grating and excitons in monolayer WS_(2).The dielectric constants of gold and monolayer WS_(2)are described by the Drude model and high-order Lorentz model respectively.The spectral response and electric field distribution of the gold grating structure and gold grating/monolayer WS_(2)hybrid structure are calculated.We study the dependence of reflection spectra on the structural parameters(grating pitch p,width l,and height h)in the gold grating and gold grating/monolayer WS_(2)hybrid structures.Based on the temporal coupledmode theory,we build a model of optical coupling between surface plasmons in the gold grating and excitons in monolayer WS_(2)and thus derive the theoretical

关 键 词：表面等离激元 一维金光栅 二硫化钨 激子 强耦合 

分 类 号：O436[机械工程—光学工程]