Localized surface plasmonic resonant based on bowtie type metallic nanostructure

With 3-D finite difference time domain (FDTD) method, we investigate the effect of the geometry parameters and near field distribution on sensitivity of the bowtie type nanoresonator biosensor in terms of refractive index. The calculation results show that the geometry parameters including gap (G), radius of curvature (R) and tip angle (A) have different effects on bulk sensitivity of bowtie metallic nanostructure. The sensitivity linear decreases as G increases while exponential decreases as R increases. Moreover, with A taking 15 degrees to 135 degrees, the sensitivity descends initially and then rises. As for the influence of near field on sensitivity, we can conclude that sensitivity is proportional to maximal local field and the scale factor of fitted curve for R is larger than the one for G.