纳米颗粒增强表面等离子共振传感器模式分析

Modal Analysis of Particle Amplified SurfacePlasmon Resonance Sensor

利用2种纳米颗粒阵列结构分析了其耦合的表面等离子体共振(surface plasmon resonance, SPR)传感器的共振模式和灵敏度。该传感器多采用Kretschmann结构,由五层材料组成,分别为棱镜、金薄膜、SiO2介质体、纳米颗粒阵列和空气。实验中选取了金球状颗粒(AuNps)和Au-SiO2核壳结构颗粒(CSNps)组成阵列层,并采用Maxwell-Garnett进行建模,计算出了相应的有效介电常数,进而结合广义反射系数分析了它们的传播特性。结果显示,AuNps阵列不同层厚和阵列几何构型对反射率和模态场分布的影响是不同的。其次,CSNps阵列结构表明,在TM极化下可以激发多种共振模式,且内核半径和壳体厚度会影响SPR传感器的灵敏度,其中内核半径对灵敏度的影响更大。纳米颗粒的间距和尺寸会影响阵列层中CSNps的浓度,从而影响灵敏度。

We analyzed the resonance mode and sensitivity of the surface plasmon resonance(SPR)sensor coupled by two kinds of nanoparticle arrays.Most of the sensors use a Kretschmann structure composed of five layers of materials:namely prism,gold film,SiO 2 medium,nanoparticle array and air.The effective dielectric constants of AuNps layer and CSNps layer of core-shell structure were calculated by using Maxwell-Garnett theory.Then their propagation characteristics were analyzed with the generalized reflection coefficient.Firstly,the simulation results show the reflectance and modal field distribution of AuNps array with different thickness and geometry.Secondly,the CSNps array structure shows that multiple resonance modes can be excited under TM polarization,and the inner core radius and shell thickness will affect the sensitivity of the SPR sensor,with the inner core radius having a greater impact on sensitivity.The spacing and size of the nanoparticles will affect the concentration of CSNps in the array layer,thereby affecting sensitivity.