Numerical Study On Properties Of Localized Surface Plasmon Resonance In Nanostructures

Localized Surface Plasmon Resonance (LSPR) of metal nanostructure has attracted considerable attention of lots of scientific researchers for it’s potential application in a wide areas. Biosensing and local fields enhancing are two main characteristics of LSPR, which is highly dependent on the shape, size and dielectric properties of the nanoparticle material. In this paper, the effect of geometry parameters of triangular nanostructures on LSPR properties is studied by three dimers Finite Difference Time Domain (3D-FDTD).We first present the theories on LSPR and the modeling process of triangle nanostructure, and then investigate the effect of the main geometry parameters including height, tip angle and radius of curvature on optical properties, sensing properties and enhanced local fields respectively. Then we do a further research on the effect of sensing media with varies sizes in different regions on refractive index sensitivity.The results show that:1) The refractive index sensitivity of single triangle vary with height, tip angle and radius of curve with the trends of linear function, quadratic function, cubic function respectively, and so is the bi-triangle’s. But under the same geometrical parameters, bi-triangle owns a higher sensitivity and a stronger averagle enhanced local field.2) The refractive index sensitivity and enhanced local field vary with gap with the trend of exponential function.3) Sensing medium at different regions is corresponding to different refractive index sensitivity in bi-triangle nanostructure, and the stronger enhance local field is in area of the sensing medium, the higher sensitivity of whole nanostructure is. More over, the sum of sensitivity of positive area and anti-area is the same with sensitivity at the condiction that the whole cover is considered as sensing medium within the error range.