基于塔姆等离激元激发法布里-珀罗谐振的折射率传感器设计  

Design of Refractive Index Sensor Based on Fabry-Perot Resonance Induced by Tamm Plasmon Polaritons

作　　者：丁冠天 关建飞 陈陶[1] 陆云清[1] Ding Guantian;Guan Jianfei;Chen Tao;Lu Yunqing(College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology),Nanjing University of Posts and Telecommunications,Nanjing 210023,Jiangsu,China)

机构地区：[1]南京邮电大学电子与光学工程学院、柔性电子(未来技术)学院,江苏南京210023

出　　处：《光学学报》2023年第14期292-299,共8页Acta Optica Sinica

基　　金：国家自然科学基金(61775102,61905117);南京邮电大学科研启动项目(NY220050,NY214058)。

摘　　要：在金属光栅覆盖分布式布拉格反射镜(DBR)双层结构中,利用金属与DBR交界面上的塔姆等离激元(TPPs)能够激发金属光栅狭缝内的表面等离激元(SPPs)的法布里-珀罗(F-P)谐振,由此产生的能量局域有助于感知狭缝内填充介质的折射率参数。为了进一步提升TPPs的激发效率,实现高灵敏度折射率传感,本文提出在金属光栅底部引入金属膜层构建金属光栅-金属膜-DBR的三层复合结构,采用有限元法分析了膜层厚度对复合结构透射谱线的定量影响。仿真结果显示,随着金属膜层厚度的增加,透射峰的谱宽单调减小,而峰值透射率呈现先增大后减小的变化趋势,在膜厚为12 nm时最大,相比无膜层结构,光谱峰值透射率提升约29%。在此基础上通过改变光栅占空比及金属光栅高度,分析了光栅狭缝中三到五阶类F-P谐振模对应的透射峰的传感性能指标。结果表明,随着占空比的减小,各阶谐振模透射峰的灵敏度显著增大。当选择占空比为60%时,四阶和五阶谐振透射峰的传感灵敏度分别升至171.20 nm/RIU(灵敏度单位)和178.35 nm/RIU。此外,改变金属光栅的高度可以实现折射率探测区间近乎线性移动,当光栅高度从900 nm增大到1200 nm时,基于三到五阶谐振模式的探测区间可以有效覆盖从1.00到2.27的折射率区间。本文的研究结果为利用TPPs进行折射率传感提供了一种有效的设计思路。Objective As a novel surface mode,Tamm plasmon polaritons(TPPs)can be directly generated by the incident light with any polarization on the interface between metal and a distributed Bragg reflector(DBR)because its dispersion curve lies inside the light cone.Significantly enhanced energy distribution on the metalDBR interface makes TPPs a potential candidate for nanoscale sensor devices.However,highly localized energy also prevents TPPs from touching the outside medium.In order to improve the sensing sensitivity of TPPs to the ambient medium,a triplelayer combinative structure has been proposed in this study,which is constituted by a metal film sandwiched between a metal grating and a DBR section.In this configuration,TPPs can be effectively excited on the interface between DBR and the metal film with a proper thickness,and a fraction of the localized energy induced by TPPs can penetrate the metal film into the grating slits to produce the surface plasmon polariton(SPP)modes supported by the metal slits.A quasiFabryPerot(FP)resonance of SPPs can be generated by a proper incident wavelength,and the highly localized energy accumulated through the FP resonance can be employed to sense the refractive index of the ambient medium.Methods The DBR section in this study is formed by the alternating dielectric layers of TiO2 with a thickness of 121 nm and ZnO with a thickness of 156 nm,which ensure a Bragg wavelength to be 1μm.Meantime,the metal gratings and film are made of silver,and the corresponding frequencydependent complex relative permittivity is described by the DrudeLorentz model.Due to the periodicity of metal gratings and the uniform distribution of the proposed structure along the slit direction,the threedimensional triplelayer structure can be simplified to a twodimensional plane unit cell model combined with the periodic boundary condition.The modal distribution and transmission characteristics of the cell model have been calculated numerically by the finite element method.The transmittance spectra of the pr

关 键 词：遥感与传感器 表面等离激元 塔姆等离激元 金属光栅 类法布里-珀罗谐振 折射率传感器 

分 类 号：O436[机械工程—光学工程]