石墨烯阵列结构中表面等离激元传播的类量子现象研究

The manipulation of light propagation in the periodic waveduide arrays is a very important idea, which has great values for potential applications in various branches of engineering. In sub-wavelength regime, the plasmonic waveguides were proposed to break through the diffraction limit. Compared to metals, graphene plasmons has attracted an explosion of research interest due to the surface plasmon polaritons (SPPs) supported by graphene undergo stronger field confinement and lower propagation loss. The quantum-classical analogies will be investigated by using surface plasmon polariton propagation in graphene sheet arrays. We build up the monolayer graphene sheet arrays by varying either the chemical potential of individual graphene in the array or the interlayer distance between adjacent graphene sheet. The propagation conditions, dispersion relationship, propagation parameters of the SPP wave supported by graphene are investigated．Spatial propagation of SPP beams in designed graphene sheet arrays offers a rather uniquepossibility to realize in a purely classical setting the plasmonic analogies of a wide variety of quantum phenomena such as tunneling, location and parity-time (PT) symmetry effect. Furthermore, we will also discuss the effects of Kerr nonlinearity on the SPP beam propagation and the novel phenomenon of discrete soliton in graphene sheet arrays. The study of linear and nonlinear propagation of SPP in graphene sheet arrays paves the way for the application of graphene to planar deep-subwavelength optical devices．

利用周期性波导阵列控制光波的传输，一直是一个重要的科学设想，并有着极其重要的实用价值。在亚波长尺度，表面等离激元波导能够突破衍射极限。相比于金属表面等离激元，石墨烯因其损耗低及灵活的调谐特性吸引了广泛的关注。本项目将研究各种不同结构的石墨烯波导阵列中表面等离激元传播的类量子现象。利用空间调制的阵列结构以及石墨烯波导的化学势变化，进而调控阵列结构中表面等离激元的衍射曲线及带隙结构，实现表面等离激元的隧穿、局域、PT对称性等一系列难以直接观察的凝聚态量子现象的光学模拟。通过引入非线性克尔介质，在石墨烯阵列结构中实现基于离散衍射与非线性光学效应相平衡的表面等离激元孤子。通过石墨烯阵列表面等离激元线性与非线性传播特性的研究，为进一步开展基于石墨烯材料的纳米集成光子学应用研究提供平台和研究基础。

在亚波长尺度，表面等离激元能够突破衍射极限，其中石墨烯表面等离激元更因其损耗低及灵活的调谐特性吸引了广泛的关注。本项目通过构造各种不同结构的石墨烯波导阵列实现表面等离激元传播的类量子现象。利用空间调制的阵列结构以及石墨烯波导的化学势变化，进而调控阵列结构中表面等离激元的衍射曲线及带隙结构。在阵列结构中引入传播系数外势场，实现了表面等离激元的克莱恩隧穿、布洛赫-齐纳振荡等一系列难以直接观察的凝聚态量子现象的光学模拟，利用耦合模式理论分析的结果与数值模拟计算结果吻合较好。通过在双周期石墨烯阵列中交替引入损耗/增益，在非厄米石墨烯表面等离激元结构中发现存在被奇异点分隔的时空对称相和时空对称破缺相，研究了受粒子-空穴对称性保护的拓扑边缘态，该边缘态局域效应不受时空对称拓扑相变的影响，在拓扑平庸和拓扑非平庸区域均可以观察到，对波导的损耗/增益扰动具有鲁棒性。该研究有望加深对于凝聚态量子理论的理解，有助于发现更多有意义的的光学现象。该结果可以推广到其它人工可调控系统，如声学，超冷原子，超导电路等，并有助于各类量子拓扑现象的研究。同时，石墨烯阵列表面等离激元传播特性的研究为进一步开展基于石墨烯材料的纳米集成光子学应用研究提供了实验平台和研究基础。