基于单挡板的MDM波导侧向耦合谐振腔的Fano共振及传感特性  

Fano Resonance and Sensing Characteristics of MDM Waveguide Lateral Coupled Resonator Based on Single Baffle

作　　者：刘加堂 李石磊 齐雅楠 陈帅 LIU Jiatang;LI Shilei;QI Yanan;CHEN Shuai(School of Physics and Optoelectronic Engineering,Shandong University of Technology,Zibo 255049,China)

机构地区：[1]山东理工大学物理与光电工程学院,淄博255049

出　　处：《光子学报》2023年第10期170-180,共11页Acta Photonica Sinica

基　　金：国家自然科学基金(No.12104261);山东省自然科学基金(No.ZR2020QA070)。

摘　　要：基于表面等离激元提出了一种含金属挡板的波导侧向耦合谐振腔系统。当入射光从波导的入射端进入到该结构时,谐振腔会形成较窄的离散带,金属挡板会产生较宽的连续态,较窄的离散态与较宽的连续态发生干涉时,形成两种不同模式的Fano共振谱线。采用时域有限差分法对该结构的传输特性进行了仿真计算,分别研究了结构的磁场分布、电场分布、透射特性和传感性能,根据磁场分布图和电场分布图可更好地解释Fano共振的形成机理。仿真数据分析结果表明,几何参数与介质折射率可以调节结构的传输性能。最后对结构的几何参数进行了优化处理,得到了在最优参数下,该结构产生的两个Fano共振的品质因数分别为4.502×105和1.967×105,对应的灵敏度分别为800 nm/RIU和1400 nm/RIU,均达到了较高的数值,具有良好的传感性能。所设计的耦合结构可为提高微纳光学传感器的性能提供一种可行的途径。Traditional optical devices have certain limitations,due to the diffraction limit,the development of optical devices is limited,making the optical devices bulky and not conducive to miniaturization.Optical devices can transmit and process information within the sub wavelength range,effectively addressing the issue.Metal-dielectric-metal waveguide can regulate the light propagation signal in the subwavelength range,and surface plasmon polariton has the characteristic of breaking the diffraction limit,making it possible to further miniaturize optical devices.Based on surface plasmon polaritons,a waveguide side coupled resonator system with metal baffles is proposed.When incident light enters the structure from the incident end of the waveguide,a narrow discrete band is formed in the resonant cavity,and a metal baffle generates a wider continuous state.When the narrower discrete state interferes with the wider continuous state,two different modes of Fano resonance lines are formed.In this paper,the finite difference timedomain method is used to simulate the transmission characteristics of the structure.The magnetic field distribution,electric field distribution,transmission characteristics,and sensing performance of the structure are studied separately.Based on the magnetic field distribution and electric field distribution,the formation mechanism of Fano resonance can be better explained.According to the analysis of simulation data,the geometric parameters of the structure and the refractive index of the medium can adjust the transmission performance of the structure.The geometric parameters of the structure are optimized.Firstly,when the side length of the Ag square is a=190 nm,the separation distance is k=10 nm,the coupling distance is g=15 nm,and the circular radius R of the structure is parameterized in steps of 10 nm from 270 nm to 330 nm,the quality factors at different R are calculated.Considering the overall quality factors of these two Fano resonances,the optimal value of the circular radius of the structu

关 键 词：表面等离激元 金属-介质-金属波导 Fano共振 品质因数 灵敏度 

分 类 号：O436[机械工程—光学工程]