基于Fano共振的金属-绝缘体-金属-石墨烯纳米管混合结构动态可调折射率传感器  

Dynamically tunable refractive index sensor based on Fano resonance with metal-insulator-metal-graphene nanotube hybrid structure

作　　者：祁云平[1] 贾迎君 张婷 丁京徽 尉净雯 王向贤[3] Qi Yun-Ping;Jia Ying-Jun;Zhang Ting;Ding Jing-Hui;Wei Jing-Wen;Wang Xiang-Xian(College of Physics and Electronic Engineering,Northwest Normal University,Lanzhou 730070,China;School of Electronic Information,Sichuan University,Chengdu 610041,China;School of Science,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]西北师范大学物理与电子工程学院,兰州730070 [2]四川大学电子信息学院,成都610041 [3]兰州理工大学理学院,兰州730050

出　　处：《物理学报》2022年第17期355-364,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:62165013,61865008);西北师范大学青年教师科研能力提升计划(批准号:NWNU-LKQN2020-11)资助的课题.

摘　　要：为了解决传统金属-绝缘体-金属(metal-insulator-metal,MIM)波导结构传感器不可动态调控的问题,本文将石墨烯纳米管引入MIM波导耦合圆环谐振腔结构,设计了一种动态可调的MIM-石墨烯纳米管混合结构折射率传感器.采用有限元法对系统的传输特性、电场分布和磁场分布进行数值研究,并通过多模干涉耦合模理论进行分析验证.结果表明,Fano共振源自于TM_(10)腔共振模式和石墨烯等离子体电共振模式之间的相干耦合.通过改变石墨烯的化学势可以在较大波长范围内动态调谐Fano共振的谐振波长和线宽,从而实现折射率传感器的动态调控.在最佳结构参数下,传感器灵敏度可达1250 nm/RIU.与传统的MIM波导结构相比,该器件具有结构简单、动态可调、易于加工且工作波段范围大等诸多优点,对设计可动态调控的高性能纳米光子集成器件具有一定的指导意义.In practical applications,the performances of conventional metal-insulator-metal(MIM)waveguide structured optical devices cured during fabrication are not dynamically tunable.In order to address the problem that such devices are not dynamically tunable,based on the excellent optoelectronic properties of graphene materials,graphene nanotubes are induced into the metal-insulator-metal waveguide coupled circular resonant cavity structure,thus designing a dynamically tunable MIM-graphene nanotube hybrid structure refractive index sensor in this work.The finite element method(FEM)is used to numerically study the transmission characteristics,electric field distribution and magnetic field distribution of the system,and the theoretical analysis is performed by multimode interference coupled mode theory(MICMT)to verify its correctness.The results show that after adding graphene nanotube to the MIM waveguide coupled ring resonant cavity structure,a Fano resonance peak appears in this system,which originates from the coherent coupling between the TM_(10) cavity resonance mode and the graphene plasmonic electrical resonance mode.The sensor can dynamically tune the resonance wavelength and linewidth of Fano resonance in a wide wavelength range by changing the chemical potential of graphene,thus realizing the performance tuning of the refractive index sensor.Hence,the problem that the conventional plasma refractive index sensor is not dynamically tunable issolved.In addition,the influence of the geometrical parameters of the structure on the sensing performance of this system is also studied in detail.The sensor sensitivity increases up to 1250 nm/RIU and the quality factor rises up to 42.4 RIU-1 at the optimal structural parameters.Compared with the traditional metal-insulator-metal waveguide structure design,this device has many merits such as wide operating band range,easy processing and dynamic tunability,which is a guideline for designing the dynamically tunable high performance nano-photonic integrated devices.

关 键 词：表面等离子体激元 石墨烯纳米管 折射率传感器 多模干涉耦合模理论 

分 类 号：TB383.1[一般工业技术—材料科学与工程] TP212[自动化与计算机技术—检测技术与自动化装置]