纳米柱阵列传感器的结构优化设计

Structure Optimum Design for Nanoparticle Cylinder Array Sensors

采用时域有限差分法(FDTD)对Ag纳米柱粒子构成的三角、方形和六角三种有限阵列排布方式下的局部表面等离子体共振(LSPR)传感特性进行了研究,讨论了三种阵列排布方式下栅格间距的变化对其消光特性、折射率灵敏度(RIS)和品质因素(FOM)的影响。栅格间距的变化使粒子间的电磁耦合发生了变化,进而改变了消光谱线,相应的折射率灵敏度和谱线的半高全宽也都发生变化。仿真结果表明,三角、方形和六角阵列的栅格间距分别为550,475和550nm时,品质因数分别取得极大值10.35,8.92和7.38RIU-1,较单个银粒子的2.76RIU-1分别提高了3.75,3.2和2.67倍。最优时,阵列结构的RIS均比单个的要高,分别为单个的1.2,1.16和1.18倍,且半高全宽(FWHM)均比单个的要窄,分别为单个的0.32,0.36和0.44倍。因此,阵列结构能够获得比单个结构更佳的传感灵敏度,且三角阵列结构比方形阵列和六角阵列的传感灵敏度要高。因此,三角阵列结构更能提高传感灵敏度,这对于纳米粒子的传感特性研究具有一定的指导意义。

The local surface plasmon resonance（LSPR）sensing properties for triangular,quadrate and hexagonal arrays consisting of Ag nano cylinder particles were investigated with the finite difference time domain（FDTD）.The effects of the variation for the lattice spacing with three array arrangements on the extinction property,refractive index sensitivity（RIS）and figure of merit（FOM）were discussed.The electromagnetic coupling between the nano particles changes with the variation of the grid spacing,resulting in the change of the extinction curves,refractive index sensitivity（RIS）and full width at half maximum（FWHM）.The simulation results show that when the grid spacings of triangular,quadrate,hexagonal array are 550,475 and 550 nm,the maximum figures of merits reach 10.35,8.92 and 7.38 RIU-1,respectively,which are 3.75,3.2 and 2.67 times larger than 2.76 RIU-1 of a single silver particle.For the optimal structure,the refractive index sensitivity of the arrays are 1.2,1.16 and 1.18 times higher than that of a single silver particle,while the full width at half maximum of the array is narrower,the values are 0.32,0.36,0.44 times of a single nano particle.Therefore,the array structure can obtain better sensitivity than the single structure of the sensor,and the sensitivity of the triangle array structure is higher than those of the square array and hexagonal array sensors.Thus,the triangle array structure can significantly improve the sensor sensitivity,which provides helpful instructions to the study of the sensing performance for nano particles.