Numerically study the method to tune the intensity of the surface plasmon

Abstract

There are two modes of surface plasmon, radiative and nonradiative. Theoretically, the evanescent surface electric fileds (nonradiative surface plasmon) have their maximum on the surface and exponentially decaying field perpendicular to it. Though the evanescent surface wave can not radiate, the enhancement of the surface electric field has become an important feature in plasmonics. Especially, if one can control the enhancement factor of a plasmonic device, that is, if the intensity of the optical near field which is excited on a plasmonic object can be adjusted exactly, there will be many novel applications implemented. Based on three-dimensional finite-difference time-domain method, we analyze the interactions of the two identical spherical silver particles with optical wave. Our results show that the electric amplitudes at the midpoint of the two particles are dependent on the direction of the alignment. We convince that by changing the angle between the alignment of the particles and the polarization, the local electric intensity would be tuned well.